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Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide

We share insights into Forbidden Runtz Autoflower week by week progress, comparing four recent grow reports
31 January 2022
31 min read
Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide

Contents:
  • 1. Grow specifications
  • 2. Grow set up
  • 2. a. Grower a: canamatoes
  • 2. b. Grower b: thebyrdman
  • 2. c. Grower c: johnnyblaze
  • 2. d. Grower d: chubbs
  • 3. Germination and seedling stage | week 1
  • 3. a. Week 1 grow conditions
  • 4. Early veg | week 2
  • 4. a. Week 2 grow conditions
  • 5. Mid veg | weeks 3-4
  • 5. a. Week 3 grow conditions
  • 5. b. Week 4 grow conditions
  • 6. Transition (pre-flower) | week 5
  • 6. a. Week 5 grow conditions
  • 7. Early flower | weeks 6-7
  • 7. a. Week 6 grow conditions
  • 7. b. Week 7 grow conditions
  • 8. Mid flower (bulk phase) | weeks 8-9
  • 8. a. Week 8 grow conditions
  • 8. b. Week 9 grow conditions
  • 9. Ripening and harvest | week 10 (and beyond)
  • 9. a. Week 10 grow conditions
  • 9. b. Week 11 grow conditions
  • 10. The outcome
  • 10. a. Forbidden runtz auto yield
  • 10. b. Forbidden runtz auto smoke report
  • 11. In conclusion
  • 12. External references

Forbidden Runtz Auto is one of the latest gems in Fast Buds catalog. This incredibly flavorful smoke will appeal to those users who love to guess what tastes it’s reminiscent of. You’ll also be thrilled with how different shades of flavor change with every new drag from the bowl. With up to 26% THC, this Indica-dominant variety is also very potent.

Read our Forbidden Runtz Autoflower week by week guide to learn the art of growing these top-shelf buds. You’ll see how this strain did in 4 different grow cycles, get insights into its typical seed to harvest timeline, and learn tips and hacks for all grow stages—from seed to flowering time to harvest.

1. Grow Specifications

Forbidden Runtz Auto is an early-flowering and fast-finishing variety. It can take her as little as 9 weeks from seed to harvest. Nevertheless, in this very short time, she can reach a considerable height of 90–130cm (35”–51”) and yield as much as 450–550 gr/m2 (1.5–1.8 oz/ft2). Outdoor results are somewhat more modest — 50–150 gr/plant.

This hybrid is leaning to the Indica side (65%), and this heritage has influenced the texture of the buds. They are golf-sized, extremely dense nuggets with swollen calyxes, frosted all over with trichomes. This generous amount of resin means extra potency. At 26% THC, Forbidden Runtz Auto is among the most powerful of Fast Buds genetics.


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: Strain data sheet

Forbidden Runtz Auto data sheet.
 

Another of the strain’s highlights is its taste which is a rich and nuanced interplay of sweet and fruity notes against an earthy background. The smoke itself—when you inhale it—is silky smooth and creamy and leaves an almost candy-like aftertaste.

2. Grow Set Up

Forbidden Runtz Auto is one of the newest additions to Fast Buds collection, and so far there are only a handful of grow reports documenting the whole of its life cycle. However, we could easily select four gardeners who did a great job sharing their experience with us. The level of detail and the quality of photos seem more than enough to give you an idea of this strain’s potential.

Grower A: Canamatoes

We have already featured Canamatoes once—with his ridiculously huge and high-yielding Gelato Auto. This guy runs a perpetual grow and provides detailed reports for every life cycle. So far, he has 24 journals and 3419 likes which have earned him the title of a Master.

His method of cultivation involves an unusual amount of high- and low-stress training. Call it OCD if you like (he himself does), but he spends a lot of time in his tent topping, tying down, and defoliating. He needs a lot of space for that, and so his autos basically occupy only one corner of his 4’x5’ ViparSpectra tent.


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: A spacious grow tent equipped with two Mars Hydro LED lights and two young cannabis plants in square containers

Containers with plants take up only part of this spacious tent.
 

He uses two 300W Mars Hydro TSW 2000 LEDs but assumes that only 150W of those go to each of his autoflowers when calculating his impressive grams-per-watt yields.

Grower B: thebyrdman

This gardener who calls himself thebyrdman is completely new to the game. The Forbidden Runtz Auto grow we’re going to review here was the first of the two grow cycles he has published so far, and he had to learn a lot on the go. He uses a 3’x3’ TopoGrow D-Door tent which is too spacious for just two autoflowers cultivated SOG-style. We’d say he would be better off growing 8-9 autos in a SOG setup. Or using bigger pots and training his plants so that they fill the entire area.

Initially, he installed a 95W ViparSpectra P600 LED light with its coverage of 2.5' x 2.5' for the vegetative phase and 2' x 2' for the flowering phase, but it didn’t have enough power for his area. So halfway through the flowering stage, he swapped to a 150W Mars Hydro TS1000.


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: Two very stretchy budding autoflowers in a tent growing through a ScrOG net

Too much room for just two untrained autoflowers in small containers.
 

His grow tent was also equipped with a trellis net which, frankly, he didn’t quite figure out how to use properly. At least not in the first of his grow cycles.

For ventilation, he uses an AC Infinity extractor fan, passive air intake, and an oscillating fan to move the air around in the tent. All in all, a very simple setup, with no bells and whistles.

Grower C: JohnnyBlaze

JohnnyBlaze is an extremely prolific gardener. In just one and a half years on GrowDiaries, he has published 46 diaries and scored 4584 likes and counting. He obviously uses several grow tents in parallel.

For this particular life cycle, he chose a kind of a walk-in enclosure, with an area of just over 3’x3’, or 1m2 to be exact. The only thing that we can say of this room is that it has tiled floors and the makeshift walls are made of drywall and a large flatscreen TV box. The guy never even bothered to cover them with Mylar or other reflective material.


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: An interior shot of a very big mature autoflower with many fat colas

This is truly one gorgeous autoflower.
 

He uses a 150W Mars Hydro TS 1000 LED light, and, although Forbidden Runtz Auto shared it with other plants, she yielded 75g of dry bud or exactly 0.5 g/W. For the lack of a good photo of the setup itself, let’s look at Forbidden Runtz Auto at the end of her life cycle. The grow room is presumably behind the door or somewhere to the left/right.

Grower D: chubbs

We have chosen chubbs as the 4th gardener to be featured here because he uses an old-school HPS bulb for the flowering stage. So it’s interesting to compare how Forbidden Runtz Auto responds to HPS vs LED. The light draws 600W, and it’s more than enough for a 4’x4’ tent.

chubbs cultivates his autoflowers in 3-gallon fabric pots filled with a soil/perlite mix. It’s a very simple cultivation method, requiring a very simple feeding schedule to achieve passable results.


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: 12 young autoflowers cultivated SOG-style in a tent in fabric pots

A 4’x4’ tent is perfect for the Sea-of-Green method of cultivation.


The table below lets you conveniently compare the tent sizes and the wattage of the lights used in all four grow cycles:

 

GrowerGrow RoomWatts UsedType of LightBrand
A5’x4’150WLEDMars Hydro
B1’x1’ / 3’x3’95W / 150WLEDViparSpectra, Mars Hydro
C3’x3’150WLEDMars Hydro
D4’x4’600WHPSUnknown

A - Canamatoes, B - thebyrdman, C - JohnnyBlaze, D - chubbs

3. Germination And Seedling Stage | Week 1

All but one gardener (the least experienced of the four) chose to plant germinated seeds straight into their final containers. The idea was to avoid such a potentially stressful procedure as transplanting.

Week 1 Grow Conditions


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: Week 1 grow conditions

Week 1 Grow Conditions.

A: Germinated, Watered, and Fed for the First Time

For his single Forbidden Runtz Auto, the grower used a popular 3-step method of germination:

  1. He soaked one seed in dechlorinated water for 24 hours until it cracked open.
  2. Then he placed the seed between wet paper towels for another 24 hrs to soften the shell, so that it would later come off more easily.
  3. Finally, he put the bean with a comfortably long tap root straight into the final 7-gal (26.5 l) fabric pot.

Another 48 hours later, the seedling was up, sans shell already. She received only a cup of pH’d water per day for the first couple of days of her life cycle. Sometimes, the grower would water around the container just to raise humidity. For the same purpose, he would also cover the seedling for several hours at a time with a humidity dome and then uncover her. The light schedule would be 24/7 from seed to harvest.

The seedling was doing great in her spacious 7-gallon home filled with a soil/perlite mix. On day 7, she received her first feeding of Mega Crop. This is a one-part formula from Greenleaf Nutrients that can be conveniently used throughout all grow stages and different stages of flowering. He also added Sea-K Kelp Extract by the same manufacturer. This organic product ensures vibrant growth thanks to a rich mix of biologically active components. 


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: A closeup of a 1 week old autoflower seedling

This vigorous young lady has just received her very first feeding.
 

The concentration of the solution was only 375 ppm which is just about right for the first feeding.

B: A Part of a Mass Start

Two Forbidden Runtz Autos were just a part of a whole batch of seeds to be germinated. The grower first put them in peat pellets, and when they started to push out one by one, he transferred the tray with the pellets into the tent and under the LED light.

He had a very common issue of seed casings stuck to cotyledons on a couple of beans and tried to remove them with tweezers but failed.

 

Word of advice: Mist your sprouts repeatedly to moisten the casings. Then they’ll come off easily. You’ll be able to simply remove them with your fingers.


By the end of the first week, the pellets were transferred to party cups filled with a Bush Doctor Coco Loco potting mix. This isn’t a regular coconut coir and perlite mixture. The manufacturer says it’s been triple-washed to reduce the salt content and requires less frequent watering than regular coco/perlite mixes. Besides, it comes amended with various organic products, such as earthworm castings and bat guano, as well such sources of natural minerals as kelp meal, oyster shell, and dolomite lime.


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: Several autoflower seedlings in plastic solo cups

Most of these seedlings will move outside, but two Forbidden Runtz Autos were chosen to spend the whole of their life cycle indoors.
 

All the seedlings that made it, including the two Forbidden Runtz Autos, looked good.

C: Germinated Straight in Her Forever Home

One Forbidden Runtz Auto seed was planted directly in the final pot. It’s not the most popular method of germination because it creates too much anxiety when you wait for the seed to sprout. However, in this case, the seedling came up promptly—on the 3d day.

She was in an 11L (2.91 gall) fabric pot filled with 75% coco coir and 25% perlite. This is an extremely effective growing medium once you master the art of watering and feeding. Coco, unlike soil, has no nutrients, so the grower had to feed his autoflower from week 1 of the vegetative phase.


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: A healthy autoflower seedling shown at 1 and 7 days from seed

A single Forbidden Runtz Auto on days 1 and 7.


He started by populating the medium with beneficial microbes and fungi (Advanced Nutrients Voodoo Juice, Piranha, and Tarantula) and also gave the girl a very small dose of pH Perfect Sensi Coco Grow A and B and B-52 (both also by AN).

While pH Perfect line would be the main source of macroelements (N-P-K), B-52 would serve as the additional source of the same nutrients but derived from such vitamin-rich organic products as kelp and seaweed.

Here’s the feeding schedule from the vegetative phase to the beginning of the pre-flowering stage.


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: The feeding schedule for the whole of the vegetative phase

Forbidden Runtz Auto feeding schedule for the whole of the vegetative phase.

D: Healthy Seedlings with no Stretch

Grower D germinated two Forbidden Runtz Auto seeds. He started with pre-soaking them in a plastic cup filled with room temperature water. As soon as the beans showed tap roots, he put them straight into final 3gal (11.36L) fabric pots with a simple mix of amended soil and perlite. Both seeds sprouted within 48 hours.


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: A solo cup used for pre-soaking a weed seed with some Fastbuds merchandise and a cannabis sprout on day 1

Two Forbidden Runtz Autos germinated in a cup and emerged within 48 hours.


Week 1 of the life cycle was great in two respects. First, the seedlings showed no sign of deficiencies or other issues. Second, they didn’t stretch at all (which is always nice in an indoor setup).


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: Two 1 week old weed seedlings planted straight into fabric pots

End of week 1, and no sign of excessive stretch.

4. Early Veg | Week 2

The first month of the life cycle started rather slow for almost everyone. Only one gardener wasn’t discouraged and began to high-stress-train his baby. The rest were waiting for the pace to pick up.

Week 2 Grow Conditions


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: Week 2 grow conditions

Week 2 Grow Conditions.

A: Two Toppings in One Week, More to Follow

In the second week of the vegetative stage, this Forbidden Runtz Auto’s patience was tried big time because she was subjected to 2 consecutive toppings. First, the apex of the main stem was pinched off, then those of the four secondary branches. The first pair of true leaves were also cut off.

 

Please be aware that topping an autoflower is always a toss of a coin, with the same 50/50 chances. Either the auto will survive, flourish, and increase the production of buds, or it will yield less or even die as a result. This particular grower himself admits it, but he accepts the risk because he likes this cultivation style.


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: A young autoflower after two consecutive toppings and with side branches spread flat and secured

This seedling has been topped two times: on days 10 and 14.


He served his lady another meal of Mega Crop and Sea-K Kelp Extract to which he also added Greenleaf Nutrients Sweet Candy as a source of carbohydrates and a way to enhance the future yield and the taste of the buds. This formula provides an extra-large dose of phosphorus and potassium (which is more suited for the flowering stage), but it also promotes the growth of mycorrhizal fungi networks in the root zone (and this is of utmost importance for the vegetative phase). He also gave her a Cal-Mag supplement which is a must in coco but never hurts in soil either. The PPM of the solution was 400 this time.

B: A Few Fertigation Mistakes Early in the Life Cycle

In week 2, the grower was overwatering his two Forbidden Runtz Auto without even realizing it. He noted the stunted growth but didn’t understand the reason. Only later, when he was away for a couple of days and left his seedlings neglected, he would see a spurt in growth. All too often, hovering over your cannabis garden is actually harmful.

Also, we couldn’t find any mention that the medium was pre-treated with a cal-mag solution. Which is a must in coco. Besides, the seedlings received nothing but plain water until the very end of week two of the life cycle. That would work in a soil mix because it contains enough nutrients till the beginning of the vegetative phase, but coco—even if it comes pre-amended—is a different story.


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: A light green autoflower seedlings with yellow leaf tips standing in a solo cup

One of the two Forbidden Runtz Autos with a slight light burn or some deficiency.
 

Anyway, the seedlings survived although they were a bit yellow and too small for their age.

C: Light Feeding and Unhurried Progress

For an experienced gardener, cultivating weed in coco basically means deciding what nutrients to mix in and at what time. Because everything else is of minor importance. So this particular grow was all about feeding schedules (which btw are so good you can use them for reference).

In week 2, two more products were added to the mix:

  • Remo Nutrients Nature’s Candy, an organic blend of carbohydrates (sugars) and amino acids to serve as food for all those bacteria and fungi from Voodoo Juice, Piranha, and Tarantula,
  • Grotek Cal-Max, this non-organic mix of nutrients contains calcium and magnesium which are needed for accelerated growth and resistance to heat, especially in coco; this product also contains iron and nitrogen, essential during the vegetative stage.

Frankly, the early development of this Forbidden Runtz Auto wasn’t that impressive. She was just barely making the cut according to the guy’s standards. 


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: A 10 days old autoflower seedling with a yellowish growing point

The span of the 1st and the 2nd pair of true leaves aren’t quite equal on day 10—rather average progress.
 

It was amazing what a monster this little girl would become by harvest.

D: No Extra Nutrients so Far

In week 2, both plants were doing great. They received nothing but water—16oz (about 0.5L) per container every 2-3 days. The leaves were flat and perky like solar panels orienting toward the light.

Btw, the day temperature in this cycle changed considerably. It started rather high (29°C/85°F) in the beginning of the vegetative phase but quickly declined (to 22°C/72°F). Somewhat lower temps are preferable for cannabis flowering stages, but this time the air got too cool too early. 


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: Two healthy and compact 2-weeks old autoflower seedlings in fabric pots

Compact seedlings with perfectly healthy leaf color.
 

Night temps were also on the low side—from 18°C/65°F in veg and early flower to 13°C/55°F in late flower. We think this affected the outcome.

5. Mid Veg | Weeks 3-4

Three out of four gardeners let their plants develop naturally, mostly because the growth in the vegetative phase wasn’t particularly vigorous. The fourth one continued with HST, pushing it to the max.

Week 3 Grow Conditions


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: Week 3 grow conditions

Week 3 Grow Conditions.

Week 4 Grow Conditions


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: Week 4 grow conditions

Week 4 Grow Conditions.

A: Steamroller-Style Training

The technique applied in the cultivation of this Forbidden Runtz Auto is called mainlining. It involves topping a weed plant several times during the vegetative phase. And each time the number of apexes doubles. So, after the third topping which was done on day 21, there were 16 tops spread flat on the surface of the soil and fixed with braces.


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: A mainlined autoflower spread flat on the surface of the medium and defoliated heavily

The third topping on day 21 (left); subsequent LST and defoliation (right).


The plant received the same diet as the week before, but at a higher concentration (716 ppm). The grower also used 2 liters of it compared to just 1 liter in the second week. The lady didn’t look particularly happy but chugged along all the same.

B: Struggling with Minor Discolorations

In week 3, the grower adjusted his watering schedule so that he wouldn’t overwater his seedlings anymore. Now he fertigated them every other day with 60ml of either a nutrient solution or fresh water.

He had been noticing burnt tips on lower leaves and was afraid it was light stress. Maybe he was right because it’s a common issue with seedlings. Light stress is manifested on lower leaves first because they have been exposed for a longer time than the new growth. But eventually, the new growth gets affected as well.

And this is exactly what happened here. New leaves began to yellow, too. The guy suspected magnesium deficiency, but it couldn’t be. Magnesium is a mobile nutrient, so its deficiency always starts at the bottom. 


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: Two healthy looking but smallish 4 weeks old autoflowers; one in a plastic pot and the other in a solo cup

Due to many minor mistakes, the growth was rather slow throughout the vegetative stage.
 

Anyway, he was giving his girls a nutrient feed one day and fresh water the next and trying to see if either was making any difference. This guessing game is very painful, especially for newbies. He also regretted that all this struggle prevented him from low-stress training his babies. We’d say the seedlings were more than healthy for that. It’s a pity they were not trained, either from the start of the vegetative phase or later.

C: A Minor Deficiency and the Start of LST

In week 3, this Forbidden Runtz Auto was still developing leisurely, so that the grower decided to postpone training her. Besides, he noticed the yellowing of tips and edges on lower leaves.

This couldn’t have been a potassium (K) deficiency because this nutrient was present in good quantities in every product the plant received. And pH was kept at a steady 6.2 which is on the higher side for coco, and K becomes deficient at low pH.

It probably wasn’t the light burn either, because the 150W LED was not too strong and at a good distance, and the girl was rather stretchy anyway. So the guy was probably right in diagnosing this as a nute burn and feeding her a bit lighter for a while.


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: A healthy but a bit stretchy young autoflower grown in coco coir and tied down for the first time

There’s some deficiency on a lower leaf, and the seedling is tall enough to require LST on day 21.


In week 4, the stretch continued. Especially after the girl was temporarily transferred into another tent with a higher-hanging light. She had been tied down at the very end of the previous week, and this stimulated the side growth.


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: A tied down young autoflower begins to develop side branches

The progress after LST over the course of week 4 of the vegetative phase.
 

The issue with burnt leaf edges spread up a bit, but all in all the color of the foliage was healthy, and the grower stopped worrying.

D: Slow and Steady Progress without any Issues

Both girls looked healthy and displayed no nute deficiency so far although they received no plant food with their water for the whole of the vegetative stage. The only thing the grower decided to do was brew them some tea using molasses to help with the transition to the pre-flowering stage.


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: Two short and wide young autoflowers in fabric pots

Week 3. Still no need for canopy management.


In week 4, both Forbidden Runtz Auto received their first training. Not because they were stretchy or anything, but to stimulate the development of side branches. At this point in the timeline, the grower expected to see the first pistils. Which he did.

 

Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: Two 4 weeks old autoflowers in fabric pots with the main stalk bent and tied down

A very simple form of LST — the tie-down method.
 

So this week would be the final one in the vegetative stage, and the girls had gone through it with no extra food whatsoever.

6. Transition (Pre-Flower) | Week 5

Most Forbidden Runtz Autos in our comparative review transitioned to the flowering stage right on schedule — at the beginning of the second month. Only one lady decided to veg for another two weeks, thereby becoming quite big and branchy.

Week 5 Grow Conditions


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: Week 5 grow conditions

Week 5 Grow Conditions.

A: The Training Continues, and the Stretch Begins

Despite the 24/7 light schedule and merciless training, the pre-flowering stage began in time for this Forbidden Runtz Auto—by the end of the first month. In fact, week 5 could be marked as the beginning of the flowering stage proper.

She even began to stretch and did it quite vigorously, standing right back up after every heavy training. Besides 3 major training sessions in one week, she was further tweaked every day so that she would go to where the grower wanted her to be. He also did a lot of defoliating.


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: A mainlined, heavily trained, and defoliated autoflower autoflower that is already budding in week 5 from seed

After 3 toppings and daily LST and defoliation, Forbidden Runtz is ready for the flowering stage.


There was a slight issue of nutrient burn the previous week, but now there were no signs of it anymore, and the girl could safely be fed a full ration of nutrients.

B: An Attempt to Make Flowering Nutes Work for Veg

In week 5, the smaller of the two Forbidden Runtz Autos was finally transplanted from the solo cup in the final 3-gallon container. Not a week too soon because the other one—which had been transplanted earlier—already transitioned from the pre-flowering stage to actual budding.

The grower tried tentatively to train the taller of them, but she showed too much resistance—the branches were already too tough to bend without breaking.


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: Two untrained stretchy autoflowers in plastic pots starting toflower in week 5 and a closeup of a flowering top

A bit anorexic but well into the pre-flowering stage already.


Being a novice gardener, the guy kept struggling with feeding schedules. He dropped one he had seen on the web and began to use the one suggested for Advanced Nutrients by Fast Buds.

He made the initial mistake of purchasing only flowering nutes, namely pH Perfect Sensi Bloom Part A and B. Although this two-part nutrient line contains every major nutrient and probably all the trace elements that cannabis needs, they have the wrong proportions for the vegetative phase. Maybe this was the reason his Forbidden Runtz looked so unspectacular in the first half of their life cycle but much better at the end of it.

Let’s have a look at the gardener’s complete feeding schedule for weeks 3 through 9 (all but the last two products are by Advanced Nutrients).


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: A complete feeding schedule for weeks 3 through 9

This feeding schedule is suboptimal; not recommended to be copied.

C: A Spurt in Growth. Finally!

So far, the gardener had been anxiously watching his autoflower week by week progress. Because it was rather slow. However, in week 5, the girl picked up the pace and looked big, healthy, and green. The canopy also promised to become very wide and flat although the plant hadn’t been topped, only tied down.


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: A big autoflower growing explosively indoors in a large textile pot filled with coco coir

Forbidden Runtz Auto progress in week 5 from seed.
 

The only thing that was lacking was the arrival of the first pistils which would signal that grow stages were coming to an end. This lady would continue to build up foliage for another two weeks.

D: Flowering Time Begins on Schedule

The training that had started in the previous week made these two babies very branchy and dense. In week 5—at which point autoflower flowering stages usually begin—the grower continued with LST noting how quickly the tops bounced back after each tie-down session.


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: Two medium-sized autoflowers in fabric pots, LST, tied down, and starting to bud

Week 5, a perfect time for entering autoflower flowering stages.
 

And although it was the beginning of the second month, these two had been only feeding on the nutrients in the soil. Nevertheless, they looked absolutely healthy, and the first flowers were already visible on the tops.

7. Early Flower | Weeks 6-7

By the start of early flower, every garden looked completely different—depending on the cultivation method used and on growers’ level of experience. 

Week 6 Grow Conditions


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: Week 6 grow conditions

Week 6 Grow Conditions.
 

Looking back on the first month and a half, we’d say plant straight into a large pot, don’t overtrain, and don’t forget about feeding if you aim for the highest yield.

Week 7 Grow Conditions


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: Week 7 grow conditions

Week 7 Grow Conditions.

A: A Very Low Profile Bush Due to HST

Starting from week 6, Forbidden Runtz Auto got more substantial meals than before—2 gallons every 5 days or whenever the container felt right. The solution was at 800 ppm and 6.4 pH. Instead of CalMag, she received Green Planet Nutrients Rezin. This amendment is supposed to increase the production of resin and essential oils thanks to molybdenum and vitamin B1 it contains.

The defoliation also continued non-stop because Forbidden Runtz Auto tended to get quite bushy. Sometimes, the grower tucked some leaves but mostly he simply cut them off. He also cut out a lot of lower bud sites hoping to channel the energy to the tops and get bigger and denser buds there. This technique is called lollipopping and is a very powerful tool.

All this canopy management which involved a lot of high stress didn’t turn Forbidden Runtz Auto into a giant like Gelato Auto (seen in the picture below on the right). However, it didn’t kill her either nor seriously stunt her progress as it so often happens when you HST an autoflower.


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: Three large heavily trained budding autoflowers grown in an indoor grow tent

Forbidden Runtz is in the corner. Not the biggest one, but she’s younger and will stretch some more.


In week 7, the plant was fertigated the same as before, but PPM was a little higher (900-1100), and the interval between waterings was reduced from 5 to 4 days. The stretch was much less than expected, and the bush remained short and squat, not as tall as many other autoflowers in the guy’s previous grow cycles.


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: A side view of a very short and squat mainlined cannabis plant in mid flower

Forbidden Runtz is 3 weeks into flowering.

B: Rather Sketchy So Far, But Eventually They’ll Deliver

In week 6, both girls stretched quite a bit and the smaller one was quickly catching up. Both were flowering now, with some ‘frost’ on the trim leaves. The grower noticed a couple of yellowing leaf tips and dialed down the nutrient solution.

His other worry was that his two plants needed different volumes of water and at different times, but, as the smaller one caught up, he was finally able to start fertigating them in one go.


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: Two very lanky stretchy cannabis plants grown indoors in a tent

The smaller of the girls is catching up quickly.


In week 7, both Forbidden Runtz Autos were already producing a noticeable smell: first of strawberry, and later of citrus. Both were filling out and getting frostier every day.

The grower had already removed some ‘scrags’ the week before. Which was the right thing to do because the girls were very tall and lanky and lower branches were too far from the light to produce anything worthwhile. This week, he also installed a trellis net and even tried to use it to push some of the lower branches in the directions he wanted.


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: Two flowering marijuana plant in an indoor tent with a trellise net installed and a closeup of a frosty bud in mid flower

The trellis net is hardly useful here. Except maybe to support lower branches at harvest.
 

Btw, the smaller of the ladies had overtaken the taller one. The grower regretted not having LSTd her because he thought she could have become a MONSTER.

C: Gear Changed to Flowering

Although the girl didn’t look like she would start flowering soon, the grower did mark weeks 6 and 7 as the beginning of flowering time and changed the feeding schedule accordingly. First, he gave her Bud Ignitor whose function is self-explanatory. This formula has no N, some P, and a lot of K (0-0.44-1.7) which presumably makes flowers pop up from top to bottom.

Another change was the switching from pH Perfect Sensi Coco Grow to Coco Bloom with its shift away from nitrogen to LOTS of phosphorus and potassium. And the third component of the flowering feed was Big Bud Coco. This nutrient has all the elements needed for big and potent buds, including cutting-edge iron chelates, the best on the market.

There were 3 more new formulas that the guy didn’t mention specifically but which play an important role during autoflower flowering stages:

  • Rhino Skin, for tougher cell walls and more rigid stalks,
  • Bud Factor-X, a cocktail of undisclosed bio-active ingredients and B-vitamins,
  • Sensizym, a mix of enzymes that, among other things, break down organic debris that accumulates in the root zone by the start of cannabis flowering stages.

In the table below, you can see the feeding schedule for the whole of the flowering time. Again, it’s so good you can safely use it for reference.

 

Nutrients, ml/l6-789-1011-12
TDS80080012001200
pH Perfect Sensi Coco Bloom A1.81.822
pH Perfect Sensi Coco Bloom B1.81.822
Rhino Skin1.51.51.51.5
Bud Ignitor22  
Sensizym1.51.51.51.5
Bud Factor X0.50.511
Voodoo Juice22  
Piranha22  
Nature’s Candy1.51.5  
Cal-Max1.21.21.21.2
Big Bud Coco 1.51.5 
B-52  1.51.5
Nirvana  1.51.5
Bud Candy  22
Overdrive   2

Forbidden Runtz Auto feeding schedule throughout different stages of flowering.


Forbidden Runtz Auto took to the new diet like a champ. She didn’t require any maintenance really besides LST and some defoliation to improve light penetration and air circulation.


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: A big and dense ganja bush grown indoors in a textile bag

In week 7 from seed, Forbidden Runtz Auto is not budding yet but filling out nicely.

D: The Start of Feeding and a Radical Haircut

These two babies began to flower before they had a chance to grow very big and have too many flowering tops. Nevertheless, they had been trained so that those few tops would be at the same distance from the bulb and get the same amount of light.


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: A top view of two LSTd autoflowers in grow bags

Not the most symmetrical but exceptionally healthy autoflowers.


It was only in week 6 that these two Forbidden Runtz Autos began to receive food for the first time. The feeding schedule was exceptionally simple and consisted of only two components, both by General Hydroponics (GHE):

  • Flora Micro/Gro/Bloom, a 3-part formula in 3 separate bottles, it is mixed at different ratios at different points in the timeline; contains all the necessary macro- and micro-nutrients, as well as silicic acid which strengthens the structure of your plants,
  • CALiMAGic, a source of calcium and magnesium which are needed in great quantities and are very difficult to supply naturally in an indoor setup.

The grower started slow, then upped the dose and kept it the same for the rest of the timeline, not counting the final flush.


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: A very simple GHE feeding schedule for cannabis flowering stages

A very simple GHE feeding schedule for cannabis flowering stages.


In week 7, both Runtz were heavily defoliated. The idea was to expose every bud site to direct light, but probably the grower got carried away and removed too many leaves. We think it eventually hurt the yields.


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: A side view of two heavily defoliated autoflowers in grow bags

Both Forbidden Runtz Autos defoliated in week 7. Perhaps too radically?

8. Mid Flower (Bulk Phase) | Weeks 8-9

Now, about 4 weeks into flowering, all Forbidden Runtz Autos but one looked like they were fast approaching harvest. Only one girl—which promised to grow the biggest—stopped stretching halfway through this phase and began to stack up. All were now resinous and smelled sweet and strong.

Week 8 Grow Conditions


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: Week 8 grow conditions

Week 8 Grow Conditions.

Week 9 Grow Conditions


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: Week 9 grow conditions

Week 9 Grow Conditions.

A: Massive, Tight, and Frosty Colas Call for the Final Flush

4 weeks into flowering, this overtrained lady began to seriously frost up and pack on weight. To boost her progress, the grower added Green Planet Nutrients Massive Bloom which is a careful blend of essential nutrients and stimulants and increases the weight and the density of colas throughout different stages of flowering.

Now Forbidden Runtz Auto was drinking 2.5 gallons every 5 days and then every 3 days in week 9. The PPM of the nutrient solution was at about 1000, but the runoff was as much as 2100 ppm.

The smell got incredibly strong around this time. First, it was just fruity, then other interesting notes appeared, such as pine, pepper, and diesel fuel


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: A multibranch autoflower with very frosty tops in late flower and a closeup of trichome covered cola

A lot of uniform-looking buds, super tight from top to bottom and covered in trichs.
 

The girl looked and smelled like she was approaching harvest, and on day 66, she was flushed with 15 gallons of fresh water until the runoff measured at around 160 PPM.

B: The New Diet Didn’t Quite Resolve the Old Issues

In weeks 8 and 9, this gardener suddenly decided to go organic. A bit late in the day for that, but okay. Besides, his Coco Loco potting mix was organic, to begin with.

So, in addition to pH Perfect Sensi Bloom Part A and B and Cal-Mag Plus he had used in the  previous weeks, he started to give his ladies the following:

  • Real Growers Recharge. This formula populates the medium with colonies of living soil bacteria and fungi which will help plants absorb nutrients regardless of whether they are organic or chemical.
  • Fish Head Farms Fish Shit. These droppings of tilapia fish (which are fed a proprietary mix of feed) are a whole ecosystem in a bottle. They work by introducing many beneficial bacteria and fungi into the root system. In this particular grow, Fish Shit—as paradoxical as this sounds—made the plants smell nicer.
  • Advanced Nutrients CarboLoad Liquid. With its mix of both simple and complex carbohydrates, this additive provides a food source for beneficial microbes in the rhizosphere.

Besides this organic cocktail, the girls were given Advanced Nutrients Overdrive that provides extra quantities of phosphorus, potassium, and magnesium for a strong finish in the last weeks of the flowering stage. At 4 weeks into flowering, the timing was about right. It was a rich diet indeed, but the nutrients weren’t dialed-in perfectly. Or maybe pH was wrong because it fluctuated in the 6.2-6.5 range while it should be a bit lower (5.5-6.0) for coco coir.


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: Closeups of deficient marijuana leaves with yellow blotches and black spots

We’d say it looks like nitrogen toxicity coupled with calcium deficiency.
 

Be that as it may, some of the leaves showed discolorations and spots, starting in the upper parts of the plants. Strangely, the green color of the foliage looked very deep despite the fact that these Forbidden Runtz were fed very little nitrogen (N) throughout the grow.

The 9th week from seeds was an ongoing struggle to dial in the feeding schedule. The grower was increasing and decreasing this or that nutrient in every feed trying to hit the sweet spot and see the deficiencies go away.

Luckily, the majority of trichomes got milky by this time, the harvest was approaching, and the guy relaxed, deciding that these deficiencies could now be called a natural autumn fade.

By the way, the yellowing of the upper leaves might have been due to light stress.


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: A top view of a stretchy lanky weed plant supported by a trellise net and a closeup of an almost mature bud covered in trichomes

What appears to be light stress is transitioning into a beautiful autumn fade.

C: A Big Hungry Thirsty Lady

By week 8, this Forbidden Runtz Auto has become very thirsty. She was drying the pot in less than 24 hours now. She also had a lot of quite prominent flower clusters and received two more budding nutes:

  • Nirvana, an all-organic flower booster that promotes bigger and more potent buds,
  • Bud Candy, the power of cranberry and grape extracts and all their bio-active ingredients to enhance your smoking experience with intense and complex flavors and scents.

The girl seemed to be happy with her life. She became the biggest one in the test run of Fast Buds genetics. However, her stretch ended in week 8. From then on it would be all about bud production.


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: A large and wide marijuana bush starting to flower in week 8 and stacking up in week 9

Flowers became prominent by the end of week 8 and started to fill out in week 9.

D: Still Small but Resinous as Hell

In weeks 8 and 9, these two babies began to fill out and pop trichomes all over the buds and trim leaves. They hadn’t really stretched and stayed very short, with very little spacing between flower clusters. The guy even decided to put a bucket under them to bring them closer to the light.


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: A small but very resinous autoflower with most leaves defoliated and a few yellowing, and a closeup of a cola white from 'frost'

Very crystally buds on both autoflowers.
 

They hadn’t really recovered the foliage lost during the week 7 defoliation, and the remaining fan leaves began to yellow, starting from the bottom. It could have been magnesium deficiency, but it was too close to harvest to bother about that.

9. Ripening And Harvest | Week 10 (And Beyond)

At this point in the life cycle, even the biggest and slowest of the Forbidden Runtz Autos had colas that seemed white from all the trichomes. Most gardeners now began to watch for the signs of maturity and to flush because all but one plant were to be chopped at 10-11 weeks from seed.


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: Height progress, weeks 1-9

Forbidden Runtz Auto height progress, weeks 1-9.
 

By week 10, most autoflowers stop their flowering stretch, so at this point in the timeline, it’s instructive to look at how the height of every Forbidden Runtz Auto in our review changed over the entire life cycle.

Week 10 Grow Conditions


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: Week 10 grow conditions

Week 10 Grow Conditions.

Week 11 Grow Conditions


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: Week 11 grow conditions

Week 11 Grow Conditions.

A: Low Temps to Quicken the Fade

After the final flush of the previous week, the grower transferred his almost mature Forbidden Runtz Auto to another tent he called a ‘chilling tent’ where he could keep the temperature as low as 55°F (13°C). There he let her fade, mature, and drink the remainder of the water from the container.

He thought she would take a full 11 weeks from seed to harvest, but in fact, he chopped her sometime after week 10. 


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: A very resinous autoflower after a pre-harvest trimming and a closeup of one mature, faded, and frosty bud

Oversized dense buds and fading leaves with some calcium deficiency; the harvest is near.
 

The stench in the tent was like something flammable, the sugar leaves changed color and even became distorted and dry as if hungry for calcium, but the buds got even fatter and denser.

B: Trich Watching and Flushing

The whole of week 10 was basically dedicated to watching trichomes for signs of maturity.

 

The problem with too stretchy cannabis is that the level of plant hormones varies too much from top to bottom. And, as a result, when the top cola seems ready for harvest, the branches down below still have too many clear trichs. If you manage your canopy to keep it relatively flat, all the buds on a bush mature simultaneously.


Anyway, the percentage of cloudy trichomes and the presence of amber ones, as well as the progress of the end-of-life fade, were unambiguous signs that harvest was just around the corner. So the grower began the final flush, adding nothing but Fish Shit to tap water (as he was advised in a local hydro store).

One of the girls still looked either burnt or deficient, but it was too late in the day to worry about that.


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: Two flimsy autoflowers approaching harvest in a tent equipped with a ScrOG net

The yellowing is progressing to the lower tops. Is it a deficiency of some immobile nutrient?


In week 11, the harvest was a bit overdue for top colas which had up to 30-40% amber trichomes while the lower buds were still shooting new clear trichs. The grower thought about harvesting in increments but wasn’t sure it was a legitimate method. (It certainly is.)


Learn how to determine the ideal moment for harvesting your autoflower in our comprehensive video guide.


On day 73, after 26 hours of darkness, he finally chopped his Forbidden Runtz Autos. The top colas looked quite impressive for a first-time gardener. If not for the lack of training, there would be several such buds on each of the plants.


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: Two closeups of mature faded marijuana buds

Main colas on both of the Forbidden Runtz Autos are more than mature on day 73.

C: Gorging on Nutes and Then Fasting

In weeks 10 to 12, the feeding schedule for this Forbidden Runtz Auto remained basically unchanged. Except Big Bud was replaced with Overdrive which is a specially formulated N-P-K-Mg blend for a strong finish in late flower.

The buds, in fact, were getting fatter and denser, and it was around this time that they began to pop an amazing amount of trichomes. The strain proved to be also very aromatic, and its smell gradually changed from citrusy to floral and earthy to extremely sour with cheesy undertones.

By week 13, the girl was ripe enough—with 70% orange pistils—to be flushed with Flawless Finish at 2 ml/l. This Advanced Nutrients product contains nothing but a small amount of Mg and its use ensures cleaner and safer smoke without any loss in flavor.


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: A heavily LSTd autoflower with many frosty tops and a closeup of one such top approaching harvest

Strong bush structure, many equal-sized tops, and a lot of resin on calyxes and sugar leaves.
 

After a full 8 weeks in flower or 13 weeks from seed, Forbidden Runtz Auto was finally harvested to be dried and cured for at least 10 days before a test smoke.

D: From Gum Ball to Golf Ball Sized Buds

By week 10, the buds were so far along that the grower decided it was time to start flushing them. In hydro and coco, a flush can be done in just a few days or a week max, but soil requires up to two weeks to do the job properly.

The guy also did the second round of heavy defoliation because the harvest seemed so near. Probably, he did it too early because it’s okay to do the pre-harvest trimming right before the chop or a couple of days before it. But if you remove the leaves a week or two before harvesting a plant, you rob her of energy and cause too much stress. It can’t but affect your bottom line.


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: A side view of two small resinous autoflowers with fan leaves removed for harvest and a closer view of a top white from trichs

These Forbidden Runtz Autos were defoliated a couple of weeks before harvest.
 

In any case, the buds did grow quite noticeably in the final two weeks and became rock hard and very sticky. One of the plants had a purple hue, and the other lime green.

9. The Outcome

Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: Setup characteristics, yield figures, and other data

Yields and timeline varied slightly, but the quality was top-notch for everyone.

Forbidden Runtz Auto Yield

Canamatoes harvested 104.89 g (3.7 oz) of buds from his extremely short thickset bush. Meaning that there was no larf which you usually get from lower branches, but only the highest quality uniformly dense nuggets.


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: A heap of dry cannabis buds on a tray with a FastBuds fridge magnet in the foreground

A nice heap of amazingly dense and resinous buds.


While thebyrdman got only 67.22 g (2.37 oz) dry from 2 plants, this was top-shelf stuff, and we’d say the yield wasn’t so bad either for a first-time attempt and the one riddled with so many mistakes.

The grower removed the fan leaves right after the chop and trimmed everything else after drying. It wasn’t that hard since the buds were thick and dense and with a great calyx-to-leaf ratio. The only issue was the sheer amount of resin jamming the scissors.


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: A closeup of a bunch of dried marijuana flowers

Very pretty looking buds for a first-timer.


The buds harvested by JohnnyBlaze were clearly leaning to the Indica side. They were compact, rock-hard, extremely resinous, and weighed 75g (2.65oz) dry.


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: A harvest of dry marihuana buds weighed on scales

A trayful of beautifully trimmed firm nuggets.


His two little ladies yielded chubbs only 34g (1.2oz) of dry bud, but the stuff was fire. Very resinous and extremely dense. Because of this density, the difference between how much went into the grinder and how much came out of it was striking. 


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: A bunch of dried cannabis branches with buds and a closeup of a very resinous bud

Very dense-looking and resinous buds.

Forbidden Runtz Auto Smoke Report

Canamatoes described the smoke produced by his Forbidden Runtz Auto as creative, energetic, and euphoric. The smell was also incredibly strong and reminded him of citrus fruit and diesel.

The two Forbidden Runtz harvested by thebyrdman were slightly different in terms of flavor, but both top-notch. Harvesting them with so many amber trichomes made the high sit heavily behind the eyes but quite euphoric. The taste of one was smooth and sweet, almost like vanilla cream with a sour fruity finish. The other had a succession of completely different flavors through the bowl: floral, fruity, caramel-like, bitter-citrusy, and fruity again.


Forbidden Runtz Auto Cannabis Strain Week-by-Week Guide: Quotes of people describing the high and the flavor of the smoke

Everyone got impressed by Forbidden Runtz Auto’s strong, complex, and sweet flavor.
 

JohnnyBlaze noted a truly unique smell of his Forbidden Runtz Auto: very fruity, with hints of cream and candy. The effect was also great: first, you get hit by a wave of euphoria and become talkative and sometimes creative, then the Indica-type sedation kicks in, but it’s not so strong that it makes you unable to function.

For chubbs, the smoke was also extremely enjoyable, mainly because of the sweet and subtle character of its taste. He thought Forbidden Runtz Auto the sweetest in the last batch of the strains he grew.

10. In Conclusion

Forbidden Runtz Auto buds have a truly outstanding bag appeal. They are compact, dense, and abundantly covered in trichomes. This makes the strain a must for any autoflower enthusiast.

When growing this variety, pay extra attention to the vegetative stage. Your plant’s vigor and health in this period depend on your love and care as much as on genetics. It’s best to avoid transplanting and put the seed straight into the final container. Also make sure to dial in the light, temperature, humidity, as well as your fertigation schedule.

As always, smart training will ensure larger plants and bigger yields, but don’t expose your Forbidden Runtz Auto to too much stress in the process. Mainlining and topping, as well as heavy defoliation probably aren’t the best idea, but LST and selective defoliation will help you increase production.

By harvest time, your ladies will be spectacular anyway because of that extra density of buds and the extreme resin content. And with a little maintenance, your Forbidden Runtz Auto can become a heavyweight champion as well.

 

Happy growing!

External References

  1. Terpenoids From Cannabis Do Not Mediate an Entourage Effect by Acting at Cannabinoid Receptors, David B. Finlay et al., 25 March 2020
  2. Evolution of the Cannabinoid and Terpene Content during the Growth of Cannabis sativa Plants from Different Chemotypes, J. Nat. Prod. 2016, 79, 2, 324–331
  3. Plant architecture manipulation increases cannabinoid standardization in ‘drug-type’ medical cannabis, Nadav Danzigerab, Nirit Bernstein, Industrial Crops and Products, Volume 167, 1 September 2021, 113528
  4. The Cream of the Crop: Biology, Breeding, and Applications of Cannabis Sativa, Susanne Schilling et al., Annual Plant Reviews online 2021 Volume 4, Issue 2, May 2021
31 January 2022