Best Marijuana Nutrients for Stimulating Growth

Garden of leafy indoor marijuana plants under fan

Nutrients are a critical part of the marijuana growing process. However, some newbie growers tend to add more nutrients than needed. All chemical elements plants need are already naturally present in water, soil, and air. Wanting to add extra nutrients is natural but you may need some extra knowledge on that. Adding nutrients can turn out to be harmful for stimulating plant growth, instead of helpful. Here are some tips on how to properly use nutrients when growing cannabis.

Cannabis plants need the following elements – nitrogen, phosphorous, and potassium (N, P, K), to grow. The winning nutrient ratio is 10% nitrogen, 5% phosphorus, and 5% potassium. Nitrogen fosters growth, phosphorus is good for the growth of roots and flowers, and potassium – for the growth of roots and photosynthesis. Organic fertilizers contain these elements under more complex and natural molecular forms.

Pick a Grow Medium and Nutrients

Growing indoors means you will have different options when choosing a medium. The most popular are the following.


Soil is the most popular growing medium. It is simple, traditional and suitable for first-time growers. Any high-quality potting soil is good as long as it doesn’t contain artificial extended release fertilizer, which is unsuitable for growing good cannabis.

Coco coir fiber

This is a soilless mixture made from recycled and processed natural fiber of coconut husks. Its pH makes it comparable to unfertilized soil. Many growers combine coco and soil as a mix.


This means that all of the plant’s nutrient needs are supplied through highly oxygenated, nutrient enriched water. The plant spends less energy growing roots and searching for nutrients, and uses more energy for growth and flowering.

Growing Stages and Nutrients

Similarly to how beings need different food during different age, each stage of the plant’s life requires different nutrients. If you are using good soil, no additional nutrients are needed during the seedling stage. All you need to do is make sure that you are growing in large enough pots to provide room for plant’s roots to grow and enough humidity for the soil. You can grow in soil without using nutrients but the best chance for that is if you grow inside.

There are some ground rules for the number of nutrients you must use during the vegetative and the flowering stage. Briefly, the pattern should be:

During the vegetative stage

Potassium must be high, phosphorus medium to high, nitrogen high. The general rule claims that ofthe amount phosphorus should be approximately half of nitrogen. Potassium levels can be between one-third to one half of nitrogen.

During the flowering stage

Potassium must be high, phosphorus medium to high and nitrogen low. During the flowering stage, nitrogen level must be significantly lowered and phosphorus must be increased. Potassium should be maintained oatthe same level as it is during the vegetative stage. A proper nutrient mix during this stage means a different NPK balance.  The percentages of nitrogen, phosphorous, and potassium are indicated on product labels with three numbers 5-18-5, each standing for the ratio of N, P, and K respectively. Each manufacturer calculates the correct proportions of each element, and the grower need to add water and stick to the designated dosage.

Apart from the NPK mix, marijuana also needs quantities of micronutrients. Most of these are already present in a good soil mix and others are often included in cannabis feed in addition to NPK. Advanced growers can also add special additives but these are not recommended if you are inexperienced in growing cannabis. The reason is that the risk of overfeeding is higher with newbie growers, and overfeeding can be detrimental to the health of the plant.


Be careful with experimenting and stick more to the safe side when growing cannabis. Being cautious with your nutrients and adding just a little nutrition can only lead to better yields. On the contrary, a plant growing in over-fertilized soil will not be stimulated. Every other watering add nutrients to the water. If you are not certain about the dosage, cut it in half. Your plant will still be well fed by this amount of nutrients in addition to the natural ones.

How to detect overfeeding or nutrient deficiency?

Nutrient deficiencies and overdoses can be detected by a change in the plant’s appearance and color. However, it can be confusing because many overfeeding symptoms are similar to those of nutrient deficiency. Either way, it is an unbalance that should be changed. Look for yellowing leaves (can be noticed during the vegetative and the early flowering stages),  peculiar leaf shape, burnt edges, brown spots or drooping leaves.

Growing marijuana is similar to growing any other plant – you need to look after it constantly and use nutrients. Do not be overzealous and estimate a proper amount of anything.

Luis Rivera has 20+ years of experience in global market expansion, business development, mergers and acquisitions, business re-engineering, finance and investor relations of software companies. He is passionate about technology, spectral science, indoor farming, food production, automation, and more. Since 2015 he is the president of Advanced LED Lights, a leading LED grow lights manufacturer based in Hiwasse, Arkansas. When not at work, Luis enjoys swimming, yoga, as well as growing grapes and flowers in Sonoma, California.

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