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How to Fertilize Autoflowering Cannabis

Nutrients are essential for living beings and autoflowering cannabis plants are no exception. In order for autoflowering cannabis plants to live, thrive, and reach their full potential, macronutrients, secondary nutrients, and trace elements must be present or added in the form of fertilizer.

If you’re growing very fast-growing autoflowering strains that are ready to harvest in under two months from germination, then quality soil will provide your autoflowering plants with the necessary amounts of nutrients for most of their life, and you’ll probably only need them once or twice fertilize twice.
This statement is only true if you use a big enough pot and smaller growing autoflowering strains, as small pots hold less soil and therefore fewer nutrients.

If you use other growing media (clay, perlite, rockwool, etc.) or regular soil without additional nutrients, you will have to add all the necessary nutrients yourself while the plants are growing. But be careful with time-release nutrients, as they can do more harm than good.

The best fertilizer for autoflowering cannabis

Fertilizer is basically a concentrated form of cannabis “food” and is calculated in the ratios of the elements N – P – K.

Nitrogen (N), Phosphorus (P), and Potassium (K) are the main elements (macronutrients) that allow your autoflowering plant to grow and produce leaves, stems, roots, and buds, and without these elements, the plant will struggle to survive Survive.

The NPK ratio is usually stated on the package of each fertilizer and can be e.g. B. be 10-5-5. These numbers mean that this fertilizer contains 10% nitrogen, 5% phosphorus, and 5% potassium. The remaining 80% consists of secondary elements (micronutrients), trace elements, and water in which all these elements are dissolved.

Autoflowering cannabis are very tough plants that require less nutrition than regular cannabis strains. This trait of autoflowering strains can be a great advantage for novice growers, as you don’t have to worry as much about fertilizing the plants and they can more easily survive environmental extremes.

If you want to fertilize your autoflowering plants with fertilizer, you must always read the label on the fertilizer packet and never give the plants more than the company recommends.

Nutrients in the seedling phase


The first two weeks after germination are the most important as the little seedling builds up its root system and is very fragile. At this stage, you must be very careful not to overfeed these small seedlings.

You can start autoflowering plants with 1/8th the recommended dose of fertilizer or even better, just water the plant for the first few weeks. If you overfeed your cannabis plant at this stage in its life, chances are the little seedling will not survive. Or if she somehow manages to survive, the overall yield of the damaged plant will be severely reduced.

If you use pre-fertilized potting soil, you don’t need to fertilize the small seedlings for the first two to three weeks.

Nutrients in the vegetative phase


Normal (photoperiod) cannabis plants have a vegetative growth phase, but autoflowering plants usually go from the seedling stage straight into flowering, so there is no distinct vegetative growth phase in autoflowering plants.

Some growers believe that the period from which the small seedlings get their true leaves to the point where they start flowering is the vegetative growth phase. It doesn’t matter what we call this stage though, because like photoperiod plants we need to fertilize it in the vegetative stage.

If you see that the autoflowering plant is growing really fast, you need to give it some more fertilizer. Usually, at this stage, it is best to give half the recommended dose of fertilizer, but if the plant becomes very bushy you can give it the full dose. Provided you don’t use pre-fertilized soil.

In the vegetative phase, cannabis requires a lot of nitrogen (N) and a decent amount of phosphorus (P) and potassium (K). The best fertilizer for autoflowering plants at this stage is the one with an NPK ratio of 10-5-5 or 20-10-10.

No matter what the percentage, just make sure there is more nitrogen (N) available than those other two nutrients. Autoflowering cannabis also needs secondary nutrients and trace elements, but commercial fertilizers designed for cannabis usually contain a mixture of these in the nutrient solution.

Nutrients in the flowering phase

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When the first pre-flowers start to appear, you need to switch the fertilizer/nutrient solution to a mixture that contains more phosphorus (P) and potassium (K).

Phosphorus is essential for cannabis bud formation and needs to be readily available for autoflowering plants when they enter the flowering phase.

A fertilizer with a ratio of 5-10-10 or 10-20-20 is sufficient, but the best fertilizers for flowering autoflowering plants have a ratio of 5-15-10 or similar since phosphorus (P) is the most important Macro-nutrient in the flowering phase.

Some newcomers to cannabis plant breeding may think that you need to stick to strict fertilization schedules, but if you follow our advice so that you don’t overfeed the plants but provide enough nutrients, you will be rewarded with a magnificent plant.

Fertilize Autoflowering Cannabis schedule

Autoflowering plants, as mentioned earlier, don’t like being over-fed and they can easily get nutrient burn. However, nutrients are essential for every stage of life! So what dosage can you give autoflowering plants?

In general, we use 1/4 or 1/2 the required dosage for normal cannabis plants, and we stick to the following regimens of growth nutrients and flowering fertilizer:

Fertilization schedule autoflowering plants in non-pre-fertilized soil (another medium)
 growth weekstage dose/fertilizer
1 week seedlingPure water
 2 weeks  Beginning of the vegetative phase1/8 growth fertilizer
3 week vegetative stage1/4 growth fertilizer
4th week Before flowering1/2 growth fertilizer
5th weekFirst bloomA mixture of 1/8 growth fertilizer and 1/8 flowering fertilizer
6th weekflowering1/2 flowering fertilizer
7th weekflowering1/2 flowering fertilizer
8th weekfloweringPure water
9th weekFlowering & HarvestPure water until harvest

This fertilization schedule can be changed depending on when your plant starts to flower and when you start seeing the first pre-flowers you need to switch from growth food to flowering food.

If we use pre-fertilized soil, this fertilization schedule is applied:

Fertilization schedule for autoflowering plants in pre-fertilized soil
Growth week Stage Dose/fertilizer
1 week seedlingPure water
2 weeks Beginning of the vegetative phasePure water
3 week  vegetative stagePure water
4th week  Before flowering1/2 growth fertilizer
5th week  First bloomA mixture of 1/8 growth fertilizer and 1/8 flowering fertilizer
6th week  flowering1/2 flowering fertilizer
7th week  flowering1/2 flowering fertilizer
8th week  floweringPure water
9th week  Flowering & HarvestPure water until harvest

These are the two fertilization schemes we use, but you can also create your own schedule depending on the fertilization