All autoflowering cannabis plants , like any other plant, need nutrients to stay alive and grow. 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. Remember you can always add more but never take away nutrients. Depending on the quantity fed to your plant you can overfeed or underfeed damaging your plant. 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. There’s a big difference between organic and inorganic nutrients, both of them can come in the three different forms we talked above but work in completely different ways. 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 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.
Inorganic nutrients work by delivering an exact amount of nutrients. 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. 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. At this 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. 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 two to three 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. Photoperiodic cannabis plants have a vegetative growth stage but autoflower cannabis plants usually go from the seedling phase straight to flowering. 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. 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. Nutrients for the Pre-Flowering and Flowering Stage. When the first pre-flowers start to appear you need to change your feeding to a mix of half vegetative and half blooming nutrients.