Growing Cannabis? These Are the Best Nutrients

Know which ones to use!

As there are an enormous number of nutrient options when growing weed, it can be difficult for an inexperienced grower to find the best combination for their cannabis plants. Arguably the biggest mistake new growers make is to turn this process into an overly complex task. Ultimately, they spend significantly more time, effort, and cash than they need to.

If you think that nutrient options are confined to marijuana plants that grow in soil, you are wrong! There are also a variety of hydroponic options, which tends to muddy the waters for the uninitiated. But fear not! We are here to provide you with a quick and easy guide to selecting the best nutrients for growing marijuana and producing fantastic yields.

What Elements Does a Marijuana Plant Require for a Successful Growing Cycle?

Even when you simplify matters, it is a fact that your cannabis plants need more than a dozen nutrients overall. The most important macronutrients gleaned from the soil are:

  • Nitrogen
  • Phosphorus
  • Potassium
  • Sulfur
  • Magnesium
  • Calcium

In ideal growing conditions, air and water will provide ample Hydrogen, Oxygen, and Carbon, which are of course the basic building blocks of life.

The first three nutrients listed above – Nitrogen (N), Phosphorus (P), and Potassium (K) – are the most crucial. If you purchase a bag of nutrients from a store, you should notice an N-P-K ratio listed on it. The ideal ratio changes throughout the growth cycle of your marijuana plants.

For instance, you need a high level of N, a medium amount of P, and a high level of K during the vegetative stage. A general rule of thumb is to remain close to a 3-1-2 N-P-K ratio for the first few weeks. If you have a high-quality soil, you can steer clear of nutrients for up to four weeks.

During flowering, it is best to reduce the amount of Nitrogen you provide, with a 1-3-2 ratio deemed to be ideal. It is essential to lower your N level at this point because it can reduce bud development and also tends to provide an unpleasant taste when harvested. P and K are more important when flowering; Phosphorus increases the number of flowers produced while Potassium helps boost the weight of the flowers.

Please note that the majority of nutrient deficiencies are due to excessively high or low pH levels in your water. Ideally, soil-grown marijuana plants will have a pH of 6.0-7.0. The range drops to 5.5-6.5 if you use Coco Noir as a growing medium or if you are growing hydroponic weed. When the pH is at the wrong level, it reduces the plant’s ability to absorb the nutrients you are working so hard to provide.

The importance of calcium and magnesium is often overlooked when discussing the growth of the cannabis plant. It is common to find them together in a single Cal-Mag supplement which normally contains Iron as well. These three nutrients are important to the process of photosynthesis, which involves creating energy from light. Magnesium, in particular, provides your cannabis plants with a major boost. It activates enzymes as well as forming the crucial chlorophyll.

While marijuana plants don’t need a large amount of sulfur, it is still a key mineral. As well as aiding enzyme formation, it helps to construct proteins. Sulfur is also pivotal in the development of chlorophyll molecules. If your plant is deficient in Sulfur, Calcium, Magnesium, or Iron, it will display symptoms such as yellowing leaves.

There are several more micronutrients. Again, while you don’t need large amounts, a deficiency in any of the following will negatively impact the health and potency of your plants:

  • Zinc
  • Molybdenum
  • Silicon
  • Copper
  • Cobalt
  • Boron
  • Chlorine
  • Manganese

What are Hydroponic Cannabis Nutrients?

The hydroponic growing process involves growing marijuana plants without soil as the growth medium. Instead, you use a different substrate such as Clay Pebbles, Rockwool, or Coco Noir. Hydroponics is becoming an increasingly popular method of growing marijuana because it offers a far higher potential yield than traditional growing methods.

Moreover, it is far easier to control the addition of nutrients because you only need just enough to ensure the marijuana plants remain upright. As hydroponics employs an open root system, oxygen and nutrients find it easier to circulate, which boosts efficiency. Once you get used to the hydroponics method of your choice, it is also simple to check on your crop’s hydration and nutrient levels.

The soaring popularity of hydroponics means the majority of nutrients sold for cannabis cultivation are hydroponic ones. Such products consist of concentrated mineral salts available in powder or liquid form. Regardless of the option you choose, you must dilute the nutrients in the water to the right level.

As you need different N-P-K ratios for the vegetative and flowering stages, there are separate products available. For vegetative growth, choose a high nitrogen ‘Grow’ solution. When your plants are flowering, purchase a high phosphorus ‘Bloom’ solution.

One problem with hydroponic nutrients is that they are very unforgiving if you mess up the dose; it is possible to kill your plants if you use too much. Begin with one-quarter of the recommended amount as specified on the product’s label and increase as necessary. Now, let’s take a look at the best nutrients when using one of the three most popular hydroponics growth mediums.


This light and inexpensive mineral is known for its water retention abilities. It consists of a silica compound and basalt, and you can buy it shredded into small blocks or in large slabs. We recommend avoiding so-called ‘isolation’ Rockwool because it is filled with potentially harmful chemicals. Dry Rockwool is also hazardous because it tends to disintegrate into minuscule pieces which you can accidentally breathe in.

If you purchase Rockwool, remember that it is an alkaline substance, which means you have to neutralize it in a solution of pH 5.5 before using it for your plants. Make sure you fertilize the Rockwool because it doesn’t lock fertilizer out. Every nutrient you provide will be immediately available to your plant for rapid growth. As Rockwool retains water so well, it is best to irrigate at longer intervals with a similar type of nutrient mix that you would use with plants growing in soil.

Coco Noir

This coconut fiber is a natural choice of growing medium. It is made up of a coconut husk, the substrate used by coconut seeds to help them germinate. Coco Noir does an excellent job of retaining minerals and water; just make sure it is clean before using it. Its water retaining abilities are akin to Rockwool, but it is recyclable and doesn’t cause damage to the lungs when inhaled.

Coco Noir has a pH of 6.5 – 7.0 which is very close to that of unfertilized soil. It is becoming increasingly common to add up to 30% perlite to Coco Noir. Overall, it is not as effective a buffer as soil, but is more forgiving than most of its hydroponic counterparts. Ideally, you will keep the pH of your water and nutrient mix at 6.0 when using this growing medium.

Growers recommend nutrient brands such as Dutch Master and Canada Advanced Nutrients when growing marijuana plants in Coco Noir. One final thing to note: Coco Noir doesn’t retain calcium particularly well, so keep your eye out for any deficiencies.

Clay Pellets

Unlike Rockwool or Coco Noir, clay pellets don’t retain water well. On the plus side, you’ll find it easy to cycle nutrients and water through without the age-old concern of overwatering your marijuana plants. The gaps in clay pellets are ideal passages for nutrients and oxygen which results in strong roots. Best of all, clay pellets are reusable, so you save money in the long-term.

Clay pellets are already high in Iron, and the Electrical Conductivity (EC) levels in this growing medium should be much lower than when using Coco Noir for example. Ideally, the EC level of the nutrient solution you use won’t be above 0.6 initially and should not go above 1.2 until the flowering stage.

Soil Nutrients vs.Organics for Cannabis – Which is Best?

The main difference between soil and the growing mediums used in hydroponics is the existence of organic matter such as manure, worm castings, compost, and hummus. The majority of the value of these forms of matter is only available in a non-soluble form. This means it has to be processed by the microbes and fungi that live in the soil for it to be effective.

If you purchase non-organic nutrients for your soil, you end up with a seemingly quick and easy package that you can add to the growing medium. However, such nutrients can build up in the soil rapidly and diminish the quality of the soil. They could even reduce a plant’s capacity to absorb nutrients. In contrast, organic nutrients and fertilizers contain fewer soluble nutrients and a greater number of elements that help soil organisms. As a result, we recommend trusting in organic material, especially if you’re a new grower.

Creating an Organic Fertilizer

A simple and cheap way to create your own fertilizer is to use organic matter such as fish meal and blood meal (both are high in Nitrogen), kelp meal and wood ash (high in Potassium), bat guano and bone meal (high in Phosphorus), dolomite lime (high in magnesium and calcium), and Epsom salts (high in sulfur and magnesium).

If you’re able to mix these ingredients in the right amounts, your main tasks during the growth cycle will be watering your plants and adding carbohydrates now and then. You can purchase pre-mixed organics, but they are pretty expensive. There are also a few other unique substances you can use as marijuana fertilizers:

  • Human urine: Did you know that your urine contains large amounts of Nitrogen? PLEASE don’t urinate directly on your marijuana plants! A much better option is to mix commercial plant food and a full bladder’s worth of pee per gallon of water. Make sure you use the solution ASAP or else ammonia will form, and this substance is toxic to your cannabis plants.
  • Chicken manure: Look for organic, slow release chicken manure compost, as it helps your plants stay healthy and also boosts your yield.
    White vinegar: You need to use a combination of baking soda and white vinegar to create carbon dioxide (CO2). Remember, your marijuana plants breathe in CO2 and exhale Oxygen (O2), so it grows well in locations with a lot of CO2. Put some baking soda in a bowl and drip white vinegar slowly into it at a rate of 30 drops an hour. Each drop creates CO2.
  • Wood ashes: This is an excellent option if you live in an area where the soil is very acidic. Wood ashes neutralize the acids and help your marijuana thrive. One shovel’s worth of ashes per 5-gallon bucket of water is a good ratio to shoot for.

Overall, organic growing is dependent on ensuring there is a healthy level of mycorrhizae and soil microbes in the soil. Although pre-mixed soil is convenient because it usually comes with a guaranteed healthy amount of these organisms, it is expensive.

It is much cheaper to create Actively Aerated Compost Tea (AACT) and add it to your soil. All you need is water from a river (or rainwater), molasses, worm castings, an air pump, an air stone, and a fish tank heater. With ACCT, you don’t have to add many nutrients or fertilizer.

There is a remarkable number of ways to grow cannabis; some involve hi-tech equipment while others require vast experience and skill. Although it is tempting to dive into the latest growth fad, it is important to remember that humans have been growing and cultivating marijuana plants for thousands of years using little more than water and whatever organic matter they could add to the soil.

If you’re pressed for time, a pre-mixed nutrient solution is best but make sure you use organic soil if you’re a newbie because it doesn’t punish mistakes as readily. Hydroponic nutrients help you produce enormous yields but require time, expertise, and attention. Above all else, analyze how much time and money you can afford to use when growing your marijuana plants. This is time well spent because it will prevent you from wasting time and money on products you ultimately don’t use.