Best Feeding Schedule for Autoflowering Plants

Usually nutrients come with instructions for photoperiodic plants so how to adjust that amount for autoflowers?
26 August 2020
21 min read
Best Feeding Schedule for Autoflowering Plants

Contents:

All autoflowering cannabis plants, like any other plant, need nutrients to stay alive and grow. Plant nutrients are divided into Macro and Micro. Macronutrients are nutrients plants use in large quantities: Nitrogen (N), Phosphorus (P), and Potassium (K). Micronutrients are the secondary elements and are absorbed in much smaller amounts: Magnesium (Mg), Calcium (Ca), Sulfur (Su), Copper (Cu), Zinc (Zn), Iron (Fe), Manganese (Mn) among others.

Both macro and micronutrients are delivered by watering with mixed nutrients, pre-amended soil, or slow-release powder, when feeding, remember that you can always add more but never take away nutrients.

 

Learn the best nutrients &  autoflower feeding schedule for cannabis with Sebastian Good.
 

Most nutrients are designed for photoperiodics, making it easier to over or underfeed and damage your autoflowering plant. That's why we recommend following the best nutrient schedule for autoflowers which has been adapted for you to grow autos using nutrients designed for photos.

  • Week 1 Seedling - Plain water;
  • Week 2 Vegetating - ⅛ veg. nutes;
  • Week 3 Vegetating - ¼ veg. nutes;
  • Week 4 Pre-flowering - ½ veg. nutes + ⅛ bloom ;
  • Week 5 Flowers taking form - ¼ bloom + ⅛ veg. nutes;
  • Week 6 Flowering - ½ bloom nutes;
  • Week 7 Flowering - ½ bloom nutes;
  • Week 8 Flowering - ½ bloom nutes;
  • Week 9 Ripening - ½ bloom nutes;
  • Week 10 Flushing - Plain water.

1. Different Types of Nutrients

Nutrients can come in different forms. The most common are diluted in water, mixed with soil, and in powder form to be used as a slow-release top dressing or to be mixed with the medium. Usually, beginner growers ask What are the best nutrients? That will depend on your preference and method of growing, there are basically two types: organic and inorganic nutrients and there's a big difference between them, both of them can come in the three different forms we talked above but work in completely different ways.

Organic vs Inorganic

Organic focuses on creating and maintaining a rich medium filled with microorganisms. By using organic nutrients you’re not feeding the plant directly, you are enriching the medium where microorganisms present to feed on the nutrients, breaking them down and making it easy for the plant to absorb.

Because you’re not feeding the plant directly, she can decide when and which nutrients to absorb so unless you do it on purpose, it’s really hard to have problems related to an excess or lack of nutrients.

 

 

Best Feeding Schedule for Autos: organic vs synthetic

Difference between organic and synthetic nutrients.
 

Inorganic nutrients work by delivering an exact amount of nutrients to the roots. To be able to do this without any damage to your plant you must really know the necessities of your autoflower. The nutrients needed for optimal growth vary from strain to strain so it’s really hard to know exactly what and when to feed. Usually, you start experimenting and if you see signs of underdevelopment or deficiencies you feed a little bit more.

On top of that, you will have to adjust the amount given to an autoflower to avoid wasting nutrients (organic) and to avoid burning your plants (inorganic). Manufacturers usually make available instructions with an approximate schedule and amounts for the products they sell but they usually are directed to photoperiodic plants. Having that in mind, we recommend always starting with half the recommended amount with autoflowers.

Slow-release

Slow-release nutrients can come in pellets or in powder form. Usually used as a top dressing or pre-mixed with soil, this is the simplest way of feeding because it slowly releases nutrients when watering. So you don’t have to worry about feeding your plant until harvest unless you see any signs of deficiency.

 

Best Feeding Schedule for Autos: slow-release nutrients

Slow-release nutrients can be added to the soil before planting or as a top dressing after.
 

The best way to water when using slow-release feeding is water more often with less water, this way the pellets or powder will dissolve faster and you won’t have any problems.

This way of feeding also comes with instructions directed for photoperiodic plants so with autoflowers you should (generally) use half of the recommended amount.

 

Sebastian Good tells you all about the right Nutrients and the right Amounts for Autoflowering Cannabis.
 

Tip: This way of feeding takes a couple of days to dissolve the pellets or powder if you water every couple of days. If you see signs of deficiency or you notice your autoflower is hungry, you can use a small amount of water-soluble nutrients to fix this immediately and give the slow-release nutrients a bit more time to dissolve.

Bottled nutrients

Bottled nutrients are what everybody knows, grower, or not. These fertilizers come in liquid form and are usually synthetic, and relatively cheap due to the wide selection available. 

Synthetic nutrients are popular amongst all types of growers, even though they’re not s safe as organic nutrients, you can effectively grow and harvest your plants without major problems. 

You can find a lot of different brands and their quality may differ but all fertilizers will contain basically the same elements and ratio for the vegetative (3-1-2) and the blooming stage (1-2-3), so it’s just a matter of preference.

 

Best Feeding Schedule for Autos: bottled nutrients

Synthetic nutrients feed the plant's roots directly.
 

Have in mind that unlike organic feeding which focuses in creating an ecosystem in the soil, synthetic nutrients feed the roots directly so you can easily burn your autos, you should always start with a smaller dose and increase it gradually, this way you can check the signs your plant gives you and can adjust the amount of nutrients to your plant’s needs, avoid wasting nutrients and most importantly, avoid burning your plants.

Remember that because these nutrients are synthetic they’ll most likely kill the microorganisms present in the soil so (depending on the medium) you’ll have to provide all the micronutrients too, like Calcium and Magnesium, for example.

We recommend using organic nutrients when possible, this way you’ll be maintaining an ecosystem similar to what you find in nature, resulting in better tasting flowers and avoid overfeeding your autos.

2. Nutrients for the Seedling Stage   

The seedling sprouts with two little leaves called Cotyledons. These leaves provide what the plant needs to survive until the first set of true leaves appear. The first two weeks of cannabis growth are the most crucial because the little seedling is establishing its root system and it is very fragile.

When to start feeding?

If you're feeding in the seedling stage you must be very careful not to overfeed. You can start your autoflower with 1/8 of the recommended nutrients or better yet, just give the plant water for that first couple of weeks. If you overfeed your plant at this stage of growth it is highly possible that the baby plant won’t survive or if it manages to survive then the overall yield of the damaged autoflower will be greatly diminished.

 

Best Feeding Schedule for Autos: plant development week-by-week

It's important to understand how your autoflower develops week by week as the amount of nutrients varies each week.
 

Tip: Water-soluble feeding gives the plant access to the nutrients immediately.

If you are using mediums with added nutrients then you don’t need to feed the plant for the first 2-3 weeks (until the pre-flowering stage). So you can relax and forget about those nutrients at this stage of its growth. 

Tip: Always read the recommendations as amended mediums contain different amounts of nutrients. Some may have the amount needed for the first weeks but others can have the amount needed up to the pre-flowering stage.

3. Nutrients for the Vegetative Stage

Photoperiodic cannabis plants have a vegetative growth stage but autoflower plants go from the seedling phase straight to flowering without the need to change the light cycle .

Some growers believe that the time when the little seedling gets its true set of leaves until it starts flowering is the vegetative growth stage for autoflowers. But it really doesn’t matter how we call this stage because we need to feed it just like a regular photo-sensitive plant in its vegetative stage.

When we see that our autoflower plant starts to grow fast we need to start giving it more nutrients. Usually, it is best to give half of the recommended dose of nutrients, but if the plant gets really bushy you can give it a full dose.

 

Best Feeding Schedule for Autos: macronutrients in the vegetative stage

Make sure your plant always gets enough Nitrogen (N), phosphorus (P) and potassium (K) on its vegetative stage.
 

At the vegetative stage, cannabis needs a lot of Nitrogen (N) and a decent amount of phosphorus (P) and potassium (K).

No matter what the percentage of the other nutrients is, just make sure that Nitrogen (N) is available more than those other two elements. Autoflower cannabis also needs those secondary nutrients but commercial fertilizers usually have a mix of the other nutrients your plant needs in the solution.

4. Nutrients for the Pre-Flowering and Flowering Stage

After a couple of weeks in the vegetative stage, your auto will be mature enough to start developing flowers, when this happens your plants will start to develop pistils, which are a sign that your plant is entering the pre-flowering stage.

When to switch to bloom nutes?

When the first pre-flowers start to appear you need to change your feeding to a mix of half vegetative and half blooming nutrients. You need to slowly start introducing more Phosphorus (P) and Potassium (K).

Phosphorus is essential for bud production and has to be available when your autoflower enters the flowering stage. Once your autoflower starts really producing bud you should start feeding only blooming nutrients.

 

Best Feeding Schedule for Autos: nutrients the flowering stage

You should slowly start transitioning from vegetative to flowering nutrients as soon as you see pistils appearing.
 

Some growers think that you must strictly go by the schedule when you are feeding your plants and if you don’t change your fertilizer your plant will not grow properly.

But the truth is that almost any fertilizer will do just fine. You can be very precise and if you have a lot of experience you can boost your yield with appropriate fertilizers but for beginners and medium level autoflower growers it is not as crucial. It is always best to give your plants less food than overfeed them. 

5. Autoflower Nutrient Schedule (Liquid fertilizers) 

Cannabis plants don’t like to be overfed and they can easily get burned because of that, the amount needed for an autoflower depends on the strain and growing environment. The following schedule should be adjusted depending on when your plant starts flowering.

 

Autoflower Feeding Chart for inert mediums

WeekStageNutrients
1SeedlingWater
2Vegetative stagevegetative nutrients
3Vegetative stage¼ vegetative nutrients
4Pre-flowering stage½ Vegetative nutrients
5First signs of flowers¼ bloom + ⅛ vegetative nutrients
6Flowering stage½ bloom nutrients
7Flowering stage½ bloom nutrients
8Flowering & ripeningFlush
9Ripening & harvestFlush

Nutrient feeding schedule for autoflowering plants.
 

Have in mind that more nutrients does not result in more growth, some plants are more sensitive to nutrients. Overfeeding your autoflowers can affect your harvest because they will need time to recover and when this happens (especially in the flowering stage), it can take up to 7 days for them to recover and continue growing normally.

Note: This schedule is based on amounts recommended for photoperiodic plants, that’s why we use ½, ¼, and ⅛ amounts. If you were to use a medium with pre-added nutrients, then you should only water until you see signs of pre-flowering (around week 4) and only then start feeding following this schedule starting from the Pre-flowering stage.

Organic Nutrient Schedule for Autos (Powdered Fertilizers) 

For those who are just starting to grow cannabis and found the table above a bit hard to understand, here’s a table that will allow you to grow autoflowers organically while keeping things simple.

We recommend using the best quality fertilizers you can find, obviously, it’s hard to find them in some places so you can use whatever you want as long as it contains Nitrogen, Phosphorus, and Potassium in the ratios mentioned below.

 

Best Feeding Schedule for Autos: worm castings

Organic worm castings are a great way to provide extra nutrients when your plants are hungry.
 

Also, depending on the water you will have to provide micronutrients so it’s recommended to use fertilizers that contain the trace minerals your plants need if you are using filtered water.

If you don’t know which brands to use, you should look into Gaia Green, Down to earth, and Dr. Earth which are the most popular brands in the market but, as mentioned before, you can use whatever you want and anything you can find as long as they’re 100% organic and respect the NPK ratios.

You’ll need:

  • 4-4-4 All-purpose fertilizer
  • 2-8-4 Bloom fertilizer
  • Organic worm castings

This method consists of pre-amending the substrate and then top dressing it every 2-3 weeks, this can change according to your growing conditions because a higher temperature can increase the speed at which your plants perform photosynthesis and the substrate may run out of nutrients earlier.

 

Best Feeding Schedule for Autos: organic feeding substrate mix

A coco and perlite mix is a great substrate because it helps oxygenates the medium while also retaining water.
 

Also, some strains may need more nutrients than others so that’s where the worm castings come in; Worm castings provide a little amount of all the nutrients your plants will need to continue growing without deficiencies until it’s time for the top dressing.

Substrate

This type of feeding can be done in any type of substrate you prefer to grow in but for better results, we recommend using the following mix: 

  • Coco fiber 90%
  • Perlite 10%

Now, as said before you can use whatever you want but this mixture has shown great results so this is what we recommend, obviously, you can and should experiment with other substrates that suit you better.

Have in mind that the percentage recommended below is based on the amounts described on the package by the manufacturer!

Vegetative stage (week 1 - 4)

This feeding schedule consists of using powdered nutrients so you have to pre-amend your soil with:

  • 4-4-4 All-purpose fertilizer - 75%
  • 2-8-4 Bloom fertilizer - 25%

After you’ve mixed the fertilizer in the soil you can go ahead and plant your auto seed in the pot for germination (or after it has germinated); These are slow-release amendments that take around 1 week for the nutrients to be available so they won’t burn your seedling.

 

Best Feeding Schedule for Autos: organic feeding vegetative stage

With organic feeding is almost impossible to get nutrient burn so you don't have to worry about overfeeding.
 

Remember that all cultivars are different so if your plants get hungry before the pre-flowering feeding you can go ahead and add the Organic worm castings as a top dress feeding, but it’s most likely that it won’t be needed with autoflowers.

Pre-flowering stage (week 5 - 8)

Once the first white hairs have appeared, you can go ahead and top dress the substrate with:

  • 4-4-4 All-purpose fertilizer - 50%
  • 2-8-4 Bloom fertilizer - 50%

Have in mind that you have to rub the powdered fertilizer gently onto the soil until it mixes completely and after it’s all mixed, water so the fertilizer starts breaking down.

Flowering (week 8 - 10)

Around week 8 (approx. 2 weeks before harvest) your plant will need that final push to fatten up the buds properly so at this stage you should feed your plant with the following ratio:

  • 4-4-4 All-purpose fertilizer - 30%
  • 2-8-4 Bloom fertilizer - 70%

This final feeding will provide the nutrients needed for your plant to develop dense buds and finish the grow cycle without any problems.

Due to these fertilizers being 100% organic, flushing is optional but depending on which fertilizers you’re using you will have to flush to enhance the aroma and flavor of your buds.

6. Nutrient overfeeding

Overfeeding is the result of a too strong solution, as said above, more nutrients don't always result in more growth and some plants are more sensitive than others.

 When you don't measure the dose of nutrients that go in your solution, you can overfeed your plants and they will surely show signs of deficiencies. Even though it's a common problem amongst growers, the problems that come along are really serious and can end up killing your plants.

 

Best Feeding Schedule for Autos: overfeeding

Cannabis plants with signs of overfeeding.
 

Signs of overfeeding are yellowing or yellow spots on the leaves and can be more serious if you don't fix it, if you continue to feed a strong solution the leaves will start to brown, get crispy and die, this results in a stressed plant which will grow slower, can end up producing lower yields and ultimately die, so if you see signs of deficiencies you should flush right away, give your plant a couple of days to recover and start feeding again with a lower dose.

Have in mind that you can easily avoid this by using our feeding schedule for cannabis above or just by simply using a lower dose than recommended and increase it gradually.

 

Nutrient Overfeeding Symptoms

NitrogenGreener leaves, weak branches, less water uptake.
PhosphorusBurned tips, thin leaves, spots on leaves.
PotassiumBurned leaf tips, curling of lower leaves, spots on leaves.
CalciumStunted growth, wilting leaves.
MagnesiumDark green leaves, stunted growth.

 

7. Nutrient underfeeding

Underfeeding can also hurt your plants, if you fail to provide the nutrients your autos need to produce sugars they won't be able to grow and will show signs similar to the symptoms of overfeeding. Even though some plants can grow well without nutrients, it's recommended you provide at least a minimum amount to make sure your harvest meets your expectations.

 

Best Feeding Schedule for Autos: underfeeding

Signs of underfeeding on fan leaves.
 

Remember that nutrients are extremely important so even though you may be afraid of overfeeding your plants, there's no need to be, it's normal for beginner growers to burn plants, even more experienced growers can burn plants when they're trying a new nutrient brand so don't worry.

Just make sure you learn from your mistakes and try to adjust the dose until you reach the optimal amount.

 

Nutrient Underfeeding Symptoms

NitrogenLeaves turn yellow, curled leaves, small leaves.
PhosphorusDark spots on leaves, curled leaves, slow growth.
PotassiumWeak branches, rusty color on leaves, slow flowering.
CalciumCurling on lower leaves, slow flowering, yellowish-brown spots on leaves.
MagnesiumDried out leaves, rust spots on leaves, sickly appearance.

 

8. Flushing and when to stop feeding

Flushing consists of washing the excess nutrients from the roots and medium 1-3 weeks before harvesting. As you may know, all cannabis plants absorb nutrients to grow, when a plant absorbs nutrients there can be a nutrient build-up, although this is more common with synthetic nutrients, it can also happen with organic nutes.

Failing to flush properly can easily affect your buds, usually, plants which have not been flushed have a less potent smell and are harsher to the throat so if you want the flavor and smell of your buds to stand out, and a smoother smoke, we recommend flushing with plain water or flushing products which can be found in grow shops.

9. In Conclusion

Autoflower watering should be taking with caution, not only autoflowers but all plants are different in one way or another. You can follow an autoflower nutrient schedule like the one we provided above but the optimal way to feed your plants is by understanding the environment you’re growing in and the cultivar you’re growing.

Our Purple Lemonade, for example, is a sturdy grower and will do perfectly fine without nutrients. 

Purple Lemonade Auto
Purple Lemonade Auto
Genes
Sativa 30%/Indica 70%
Genetics
Purple Lemonade
Flowering
9 – 10 weeks
Harvest
400 – 500 gr/m2
Height
70 – 120 cm
THC
Up to 22%
CBD
< 1%
Autoflowering
Yes
1 fem
13,00 €
2 fem
24,00 €
3 fem
36,00 €
5 fem
55,00 €
10 fem
99,00 €
25 fem
215,00 €
50 fem
365,00 €
100 fem
590,00 €
500 fem
1 950,00 €
1000 fem
3 400,00 €
Pack
3 fem
Add to Cart
36,00 €
 

But with proper usage and good quality nutrients, she will make absolute marvels. 

The amount of water and nutrients an autoflower needs depends on humidity, temperature, type of medium, air circulation, and genetics so we recommend spending a little bit of time with your plants daily. Paying attention to the little details and signs that your plant gives you, this is where you make the difference between growing an okay plant and a beautiful, 100% healthy one. We promise she will give back by growing dense and very frosty flowers.   


This post was most recently updated on January 22, 2021.

 

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