Cannabis plants require more than just water to grow big and strong, they require the right balance of macro and micronutrient fertilizers throughout their life cycle.

There are many types of fertilizers on the market ready and willing to feed your plants including organic, synthetic, or a mix of both. Each option has their benefits and disadvantages.

Synthetic Chemical Fertilizers

synthetic fertilizersSynthetic fertilizers are created with exact NPK ratios and micro and macro nutrients designed for both stages of cannabis growth.

The nutrients in these types of fertilizers become available for plant absorption quickly for faster growth.

Given this enhanced growth, it becomes incredibly important to pay extra attention to your plants in order to correct any sudden deficiencies that may arise.

Synthetic chemical fertilizers are perfect for hydroponic and passive hydroponic systems.

Mixing chemical fertilizers will vary by product and growth stage and monitored with a PPM meter in order to avoid making your feed to “hot” and burning your plants root system.

Some of the more popular cannabis chemical fertilizers on the market are:

Powdered Nutrients you mix yourself include:

Organic Fertilizers

organic fertilizersOrganic Fertilizers use more natural mineral sources that include limestone, manure, guano, compost, seaweed extracts, and worm castings.

Many organic nutrients are provided as raw materials and mixed in with your base soil, these may require treatment or composting.

Organic nutrients are more environmentally friendly. Organic compounds may require additional time to breakdown in the soil in order to transform and become the elements that plants can uptake and consume.

Micro and Macro Nutrients

Cannabis plants absorb the macro and micronutrients from water, air, and soil.

Plants absorb basic elements such as Oxygen, Carbon, and Hydrogen from the CO2 in the air and both filtered and non-filtered water.

Proper airflow in your grow room will ensure the proper intake of carbon and oxygen to your plants, while water is necessary for basic plant function. Filtered water tends to remove chlorine and other harmful compounds that could stifle plant growth.


cannabis fertilizerMain plant nutrition are the macronutrients and designated NPK which stands for Nitrogen (N), Phosphorus (P), and Potassium (K). These macronutrients are vital to plant nutrition and will be designated on every nutrient on the market.

Lower level, but just as important macronutrients are Calcium, Magnesium, and Sulfur.

Micronutrients come in the form of Manganese, Boron, Sulfur, Iron, Molybdenum, Zinc, and Copper. These nutrients are also included in all basic fertilizers.

Other beneficial elements include Silicon/Silica (Si) which helps your plants build healthy and strong cell walls, stems and leaves. These elements are common when using soil but may need to be added when working with hydroponic and coco-based systems.

Fertilizer Numbers and How to Read Them

Fertilizer labels will have three main numbers which represent our primary NPK as mentioned above.

An example of this would be NPK 2-13-10 which tells us that our fertilizer has 2% of nitrogen, 13% phosphorus, and 10% potassium.

Cannabis is unique in that it requires specific levels of NPK for both its vegetation and flowering cycles.

A basic NPK ratio for cannabis would be 3:1:1 throughout the vegetative stage. This provides the highly needed nitrogen for the plant during this time.

Once the plants begin to flower, switching to a 1:3:2 then brings down the nitrogen and increases the phosphorus and potassium levels during the flowering stages.

Late flower (a few weeks before harvest) the nitrogen can be removed completely giving us more of a 0:3:3 ratio.


There are many supplements on the market that are used in conjunction with your basic fertilizer and meant to help conditioning of the soil and give your plants a boost once established. It’s always best to start off with your basic nutrient fertilizer, then add supplements as needed.

Many supplements are intended to increase your plants absorption of your fertilizer which promotes and increase in cannabinoids and terpenes with an added benefit of increasing resistance against pests and disease.