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When is the Best Time to Harvest Autoflowering Cannabis?

Brown Pistils? Cloudy Trichomes? When should you harvest and how to harvest your cannabis plants?
11 August 2020
20 min read
When is the Best Time to Harvest Autoflowering Cannabis?

Contents:

The best time to harvest your plants depends on factors like proper flushing and the effect you wish to get, every plant is different and the only way to be sure is to take in consideration all the signs your plant gives, especially the stigmas and states of the trichomes.

After you properly flush your autos, there’s a “harvest window”, this is the time when your plants are ready and you have to decide when to harvest. There are several things to have in consideration and depending on when you do it, you can get a different type of effect.

1. How to know if my autoflower is ready for harvest?

It really doesn’t matter if you’re growing indoors or outdoors, the time will come and you’ll have to harvest your cannabis plants. 

Now, cutting a plant isn’t hard at all but if you’re a first-time grower it can be hard to know exactly when to do it, depending on the plant (Indica or Sativa-dominant) and if it's an auto or photo, it can take a lot more (or less).

 

 AutofloweringPhotoperiodic
Sativa10 weeksup to 16 weeks
Indica8-9 weeks12 weeks

Average time from seed to harvest.
 

The best time to harvest your plants depends on a combination of different factors and what you desire to get, it can take a little bit longer if you want to properly flush your plants or get a more Indica-like effect or less if you prefer a more Sativa-like effect, either way the best time to harvest your autos (once your plant is in the “harvest window”) will depend on the type of effect of your preference.

2. Harvesting based on the seasons

Planning your harvest by the seasons depends on the place you live in and in knowing the expected weather.

For example, during summer you can get up to 15hrs of sunlight, but when autumn comes the amount of sunlight decreases drastically, although this won’t make your autos flower because they don’t depend on a light cycle to start flowering, it can affect yields.

 

Harvest Your Autoflowering Cannabis: harvesting based on the best seasons

Harvesting based on the seasons is the best way to guarantee the best possible harvest.
 

The best way to prevent this is to make a grow calendar before germinating your seeds, some places can get as little as 9:30hrs of sunlight during winter so by planning ahead you can get more yields and know when you’re going to harvest your plants.

The best time of day to harvest you plants is early in the morning, before the sunrise and if you can, leave your plants in darkness for even more. Leaving your plants in complete darkness for up to 48hrs will let your plant know that she's about to die and she will make a final effort to produce more trichomes, resulting in a better harvest.

This also applies to cannabis plant grown indoors but because you are growing in an enclosed space there's no need to harvest before the sunrise, you can turn the lights in your growing tent off and leave them there for approximately 2 days.

3. The Vegetative stage: Week 1-5

Before starting to look for the signs that indicate your plant is completely mature, she has to go through the whole vegetative stage which starts as soon as your plant starts performing photosynthesis, starting from week 1 all the way to week 5 with autoflowering strains. In the vegetative stage (aka growing phase) your plants will only develop their structure and even though they're not producing buds, it's super important because it's the period your plant has to grow the leaves which are used in photosynthesis and develops the branches and stem, which are the part of the plant that support the buds.

Without a proper growing phase, the branches can snap if the buds fatten up too much, or if your plant doesn't grow too much, the yields will be affected.

 

Girl Scout Cookies timelapse video by Basementganja.
 

In this video you can see a timelapse of our Girl Scout Cookies Auto from seed to the last week of its cycle, notice how not only the leaves but also the branches slowly start to develop and get thicker and thicker each day, these are signs of a healthy plant.

By maintaining a good growing environment you ensure your plant is happy and healthy and that is the best way to guarantee a good harvest.

4. Ripening of the buds

Before you are in the “harvest window”, your auto plant needs to develop and ripen the flowers. This starts when your plant enters the pre-flowering stage (around week 5) and can take up to 5 weeks (depending on the strain).

Week 6

Around week 5 your auto is entering the pre-flowering stage and you will see stigmas (white hairs) starting to come out from the pistils, the pistils contain the ovule, style and stigmas and are responsible for producing the seeds when they get pollinated.

 

Harvest Your Autoflowering Cannabis: ripening of the buds on week 6

Zkittlez Auto on week 6 by our grower Johnnyronco.
 

This is his first time growing autos, by keeping the temperature steady and the right humidity he was able to grow a really healthy plant, with beautiful dark green leaves and several bud sites.

Starting to smell, really defoliated a lot last week and lots of lst. This week I’m going to let them recover. They are very thirsty girls, lots of nutrients and water and they keep asking for more.

Week 7

In the second week, your auto is in full flower and you will start to see a lot of stigmas and your buds getting thicker and thicker each day.

 

Harvest Your Autoflowering Cannabis: ripening of the buds on week 7

Gelato and Gorilla Glue on week 7 by our grower 1. MrNice420 and 2. AutoBravado.
 

In this stage is when your plants usually start to smell really strong, if you live in a place where cannabis smell can be an issue, it's recommended to install a carbon filter to help eliminate the smell. 

As you can see, the bud sites are starting to develop a lot of pistils and the trichomes are starting to appear in abundance, this is usually when cannabis plants start to smell but that can vary depending on the strain you're growing.

Week 8

By the third week, the flowers start to ripen, you may be able to see the tip of some stigmas starting to turn brown, also, the amount of trichomes will be more visible although the trichome heads aren’t full of terpenes and cannabinoids yet.

 

Harvest Your Autoflowering Cannabis: ripening of the buds on week 8

LSD-25 Auto on week 8 by our grower Mos40.
 

In this week your buds should be starting to fatten up, with some pistils already turning brown and, in some strains, different hues will start to appear. In this case, the LSD-25 started to fatten up the purple calyxes, swollen calyxes is a sign your plant is getting ready to be harvested and is something you should be on the lookout for.

Week 9 

On week 4 almost all stigmas will have turned brown, the calyxes will be fat and plump, and there will be an abundance of trichomes that contain a good amount of terpenes and cannabinoids but are not yet full and have not reached its peak potency.

 

Harvest Your Autoflowering Cannabis: ripening of the buds on week 9

Purple Lemonade Auto by our growers 1. ButtersStotch and 2. Culinarychemist.
 

This is the week before the last one and you can see it in the photos our growers were happy with the density and aroma of the buds, which are completely covered in pistils and extremely frosty, at this stage you are only waiting for the flowers to get ready and when you get to this point, you'll know the buds are almost ready.

It is however consistent in the aroma it puts off, very fruity and pleasant. Buds are thickening you and are beautiful, I just love this strain!

Week 10

By the fifth week, your plant should be completely mature, with the trichomes completely upright and full of the compounds that you love.

 

Harvest Your Autoflowering Cannabis: ripening of the buds on week 10

Strawberry Pie Auto on week 10 by our grower Hawkbo from Grow Diaries.
 

After your plant has completely finished it's life cycle, you are ready to harvest it, although this doesn't mean you can smoke it right away. To be able to smoke your flowers properly and experience the flavors and effects you still need to dry and cure your buds.

You can clearly see there are still some white pistils but the majority is already brown and the plants is extremely frosty with the trichomes cloudy, this means it's ready to be harvested and will have a more cerebral effect.

5. Flushing 

The first step to harvesting your autoflowers is 'flushing' the plant. Flushing consists of washing the excess nutrient off the medium and roots, and it’s the best way to ensure your plants aren’t harsh and have a delicious smell and taste, this process should be started 2-3 weeks before harvesting, especially when using synthetic nutrients.

This gives the plant time to use all the remaining sugars and nutrients its storing. If you don't flush, excess amounts of both end up in your final product, and they burn alongside your bud, giving it a harsh feel and flavor.

 

Harvest Your Autoflowering Cannabis: flushing

Flushing removes the excess nutrients in your plant and will result in better tasting flowers.
 

How long you flush depends on your growing medium, but the result is the same. Flushed weed is incomparably smoother.

When to start your flush is up to you, but one sure sign an autoflowering plant is ready to go on a terminal diet is yellowing leaves. If your fan leaves have been lush and green throughout, the first signs of yellowing let you know its time to begin the harvest process and start flushing.

6. The harvest window

The harvest window refers to the last days of your auto’s life cycle. It starts once you’ve started flushing: the leaves are turning yellow, your plant is not absorbing any more nutrients, and is almost ready for harvest.

When you’re in the harvest window, you have to look at different parts of the buds. You can get a more cerebral effect, a corporal effect, or a mix of them both if you know exactly when to harvest to get the desired effect.

You need to take a look at a combination of the following elements to be able to harvest at just the right time.

7. Approximate breeder’s schedule

Almost all breeders give you an approximate number of weeks a certain strain takes from seed to harvest, this schedule depends on your growing setup and should not always be followed.

 

Harvest Your Autoflowering Cannabis: breeder's schedule

The breeder's schedule is not exact and should be used as a guideline.
 

Obviously, that information can be used as a guideline but remember that breeders have top-notch growing spaces so how long your plants take will depend on your growing conditions.

Cannabis plants can take less or more time than what is specified depending on the intensity of the light, you should not harvest exactly when they say but you can use it to start looking for the signs that your plants are almost ready for harvest.

8. When you notice less water usage

When a cannabis plant is almost ready for harvest it won’t absorb too much water because it’s in the process of ripening the buds and doesn’t need to grow more.

  • Throughout your plant's life cycle, you’ll be able to see how long it takes for the soil to dry;
  • If your plant is maturing and it’s not absorbing too much water, it’s a sign that it's almost time to harvest;
  • Although this isn’t too precise, it should be taken into consideration but not used as the only parameter to harvest the buds.

9. Yellowing and dying fan leaves

If you flush properly you will start to see the leaves yellowing and dying at the end of your autos life cycle, this means your plant is not absorbing any more nutrients and is focusing the energy on the buds.

 

Harvest Your Autoflowering Cannabis: yellowing leaves

The leaves will yellow and die throughout the flushing process and it's a sign your plants are almost ready for harvest.
 

Yellowing leaves are a sign of deficiencies and are a problem at any other stage but in the final weeks it’s completely normal, this means you’re successfully removing the excess nutrients and your plants are getting ready to be chopped off.

10. Calyxes become plump

Calyxes are the part of a cannabis plant that protects the reproductive organs and what form the buds, they are designed to hold the seeds when a plant is pollinated and are the first sign of flower formations, they start as a bunch of small leaves and fatten until the flowers are fully formed.

When you are near harvest time, you'll see the calyxes are round and plump, this is another sign that your plant is reaching maturity. 

11. Color of the stigmas

Pistils grow from the stigmas1(like mentioned above) and they can be a sign that your plant is completely mature. These long, hair-like organs on the surface of the bud usually start out whitish-green and darken to brown, and red as time goes on.

Although it isn’t a rule because some autos can have brown pistils and still need a couple of weeks to be harvested.

 

Harvest Your Autoflowering Cannabis: brown stigmas

When most of the stigmas have turned brown it means your plant is nearing the end of its life cycle.
 

The stigmas are the part of the cannabis plant that catches the pollen to produce seeds, when they aren’t pollinated they will start to turn brown and wilt, when around 60-70% of the pistils are brown it means a plant is reaching the end of its life cycle and can be ready or almost ready for harvest.

This method is easy to do and requires no specialized equipment, but it's not the most accurate or reliable. New pistils can appear overnight, setting your time to harvest back days. Some strains are more prone to producing dark-colored pistils, regardless of how ready to harvest they are. 

12. States of the trichomes

The sticky trichomes basically consist of a stalk and a head or cap, they contain terpenes and cannabinoids that are produced in the trichome’s head and are responsible for a plant’s aroma.

The smell of a cannabis plant gets more intense throughout the flowering stage because there are more trichomes on your plant and when you reach the harvest window the trichomes also go through a ripening process.

 

Harvest Your Autoflowering Cannabis: trichomes

The different states of the trichomes help give you an idea of the effect the buds will have.
 

In order to be more accurate than looking at the stigmas, you're going to have to look at the trichomes, the sticky balls of resin you see on well-grown bud. These specks contain most of the THC and other cannabinoids you love to smoke.

Trichome color is considered the standard indicator when finding the right time to harvest, when your plant is ready for harvest the trichomes will start to ripen, the cannabinoids will start to deteriorate, and depending on when you harvest them, you’ll get a different effect.

Even though you can view the trichomes without equipment, a simple magnifying glass should be enough to get a good view of their plant's trichomes. More serious growers, however, will probably want to go the extra step of investing in a high-quality jewelers loupe to get a better view.

 

Autoflowering Cannabis: states of the trichomes

Clear trichomes aren't fully matured, cloudy trichomes are on their peak potency and amber trichomes have a more Indica-like effect.
 

Professional growers take that even further and often use digital microscopes to get the best view of their buds. Depending on the laws where you live, you may find these microscopes at your local dispensary or cannabis club. Customers can use these to confirm their weed is properly grown and harvested before purchasing.

Under magnification, trichomes take on the appearance of mushrooms made from crystal clear blown glass. As the plant nears harvest time, their transparent appearance will grow cloudy and if left for longer they will turn amber. If this is your first grow, it will take your time to learn to tell them apart.

13. Early harvest vs late harvest

What happens if you’re forced to move your harvest date?

If for any personal problems you're forced to harvest your plants early (or late), the trichomes will not be mature enough or they will keep degrading over time so you should take a look at your plant and decide what is best for your case.

Early harvest

If something happens and you're forced to have an early harvest or late harvest, you'll probably not be harvesting your plants when they are more potent, if you harvest early the trichomes will not be fully mature and the effect when consuming your buds won't be as strong.

 

Harvest Your Autoflowering Cannabis: clear trichomes

Clear trichomes on a cannabis flower from @erik.nugshots1 from Instagram.
 

Immature or clear

Immature or clear trichomes are not potent because the cannabinoids are not fully developed, this means you will not have a psychoactive effect so you shouldn’t harvest yet but be on the lookout because it won’t be long until the trichomes start turning cloudy.

In the final weeks of flowering, trichomes can mature in a couple of days or even overnight so keep an eye on them so you harvest at the right time.

Mature or cloudy 

When the trichomes are mature2 or cloudy is when they are their peak potency and it’s when you should harvest your plants if you want a cerebral kind of high, have in mind that it’s impossible to harvest when all the trichomes are mature because your plant will continue to produce new trichomes until it’s chopped.

 

Harvest Your Autoflowering Cannabis: clear trichomes turning cloudy

Clear trichomes with purple hues turning cloudy from @erik.nugshots2.
 

So to get this effect, you can harvest your plants when around 85% cloudy, the other 15% being a mix of amber and clear trichomes.

Late harvest

If you harvest late, the trichomes will start to age and as they turn amber the THC will start to turn into CBN, resulting in a more Indica-like, corporal effect.

Even if they've gone from cloudy to amber, you're still OK, but because the THC has turned into other cannabinoids, the effects you get when smoking will change a bit.

This isn't usually a problem if you're aiming for a strong Indica high, but it's crucial you harvest at the right time if you were hoping for a Sativa-like type of effect.

Overripe or amber

Overripe trichomes are those which have turned amber because the THC has begun to degrade into CBN, although this isn’t desired by many, some consumers prefer a more corporal and narcotic effect so if you desire that type of effect, this is when you should harvest your plants.

 

Harvest Your Autoflowering Cannabis: cloudy and amber trichomes

Cloudy and amber trichomes on the buds.
 

Remember that you can harvest your plants when you want to, by knowing the effect of clear, cloudy, and amber trichomes you can effectively harvest your plants to get the effect you want, you don’t necessarily have to harvest when the trichomes are 85% cloudy or amber.

For example, you can harvest when the trichomes are 50% amber and 50% cloudy so you get a balanced effect or at any ratio, you wish to, as long as you don’t harvest too early.

14. In conclusion

Knowing when to harvest isn't an exact science, but these rules should steer you in the right direction. For the best results, you should combine the methods described above. If you're shooting for THC-rich buds, you should harvest when 50%-70% of your pistils have changed color, and most of the trichomes have turned cloudy.

Growing cannabis requires a lot of time and hard work but the results make it worth it, even after your plant is completely mature there’s still some work left to be able to enjoy your flowers.

The harvesting, drying, and curing are super important when growing cannabis, and not doing it properly can ruin the potency, taste, and smell of your buds, we hope our guide helps you and if you have any questions or encounter any problems, feel free to leave us a comment below!


This post was most recently updated on August 11, 2020.


References:

1, 2 Photos courtesy of Erik Christiansen - https://www.instagram.com/erik.nugshots/

External References:

  1. The Cannabis Plant: Botanical Aspects, Farag, Sayed & Kayser, Oliver, (2017).
  2. Cannabis glandular trichomes alter morphology and metabolite content during flower maturation, The Plant Journal, 2019.

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