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Cannabis Nutrients: Why, How, And When To Feed Your Plants

Cannabis plants are sensitive to nutrients, and there’s a fine line between properly feeding your plants and burning them with chemicals. Find out everything you need to know about properly feeding cannabis plants in our guide!

A full rundown on why and how to feed your cannabis plants.

  • 1. Understanding cannabis macro and micronutrients
  • 2. Not all cannabis fertilisers are made equal
  • 3. Nutrient requirements for seedlings, vegging, and flowering weed plants
  • 4. How to read a feed chart: How often should I feed my weed plants?
  • 5. How to prepare cannabis nutrients
  • 6. The importance of PPM, pH, and water temperature
  • 7. Tips for better feeding
  • 8. Recognising cannabis nutrient-related problems
  • 9. Organic vs chemical fertiliser for cannabis
  • 10. Wrapping your head around cannabis nutrients
  • 1. Understanding cannabis macro and micronutrients
  • 2. Not all cannabis fertilisers are made equal
  • 3. Nutrient requirements for seedlings, vegging, and flowering weed plants
  • 4. How to read a feed chart: How often should I feed my weed plants?
  • 5. How to prepare cannabis nutrients
  • 6. The importance of PPM, pH, and water temperature
  • 7. Tips for better feeding
  • 8. Recognising cannabis nutrient-related problems
  • 9. Organic vs chemical fertiliser for cannabis
  • 10. Wrapping your head around cannabis nutrients

All the nutrients needed for cannabis plant development are naturally present in the environment. However, to help your plants develop even faster and produce a better end product, you’ll want to feed them with fertiliser—concentrated nutrients.

Below, you’ll find all the information you need to know about when, how, and how much to feed your cannabis plants.

UNDERSTANDING CANNABIS MACRO AND MICRONUTRIENTS

Cannabis plants require three nutrients in large quantities. These macronutrients are nitrogen (N), phosphorus (P), and potassium (K), and they form the cornerstone of cannabis plant health. As such, these three nutrients usually feature front and centre on fertiliser products in the form of an NPK ratio. The higher the number for each value, the higher the concentration of that particular nutrient.

However, cannabis needs more than just three nutrients to survive and thrive. It also counts on secondary nutrients like calcium, magnesium, and sulfur to play vital roles in plant growth:

  • Calcium is important for cell wall development, can help reduce soil salinity, and improves water penetration when used as a soil amendment.
  • Magnesium plays a key role in photosynthesis and carbohydrate metabolism, and also helps with the stabilisation of plant cell walls.
  • Sulfur is necessary for the formation of chlorophyll and the production of proteins, amino acids, enzymes and vitamins, and protects plants against disease.

Beyond this, plants also make use of several other nutrients in small quantities (micronutrients) that are nevertheless extremely important. These include boron, chlorine, copper, iron, manganese, molybdenum, and zinc. While these aren’t the main nutrients plants use for food, they still play very important roles in various aspects of plant health.

NOT ALL CANNABIS FERTILISERS ARE MADE EQUAL

There are many different brands of cannabis nutrients on the market, and they can differ considerably.

Typically, cannabis fertilisers will vary in the four following areas:

  • Nutrient ratio: Different brands use different nutrient ratios they consider optimal.
  • Ingredients: Different fertiliser brands can achieve the same nutrient ratios using completely different ingredients, ranging from the most chemical (or “artificial”) to the most natural.
  • Soil or hydro: Soil nutrients are very different from hydro or soilless nutrient solutions. Make sure you only use fertilisers designed for your growing medium.
  • Supplements: Many fertiliser brands also make “supplements”. These products typically contain low NPK ratios and instead feature other nutrients designed to boost certain aspects of growth. Some supplements, for example, are essentially molasses.

In general, we recommend you focus more on meeting your plants’ demands for macro and secondary nutrients before pumping them full of supplements. Going overboard with nutrients can result in chemical interactions or nutrient burn, which can significantly impact the size and quality of your yield.

Once you’ve nailed feeding your plants with these core nutrients, feel free to move on to a more complex feeding schedule to produce bigger, more potent harvests.

Wondering when and how to feed your cannabis plants? Click here for the ultimate guide to cannabis nutrients and how to use them to produce excellent harvests.

How to Use Liquid Nutrients for Cannabis Plants

L iquid feeding–the process of applying nutrients with a liquid mixture–is the most common way to provide a cannabis garden with the nutrients needed to thrive. Used with soils or other growing mediums, liquid fertilizers may be the only input or utilized in conjunction with other feeding methods.

Liquid feeding begins by preparing a solution in a mixing tank with water. This solution is fed to the roots to promote healthy, strong growth. Because liquid nutrients are readily available to the roots, they are fast-acting–which can also damage your plants if you feed them too much.

In this article, we’ll look into what makes liquid fertilizer unique, as well as when and how to liquid feed cannabis plants.

Advantages of Using Liquid Fertilizer for Cannabis

Liquid feeding is the go-to method for both soil and soilless cannabis gardens. In soilless setups, liquid mixtures allow precise control over what nutrients make their way into your cannabis plants. With soil-based grows, you can easily give your plants a boost by applying liquid fertilizer if the soil doesn’t provide enough nutrients to sustain your plants. This precise method of feeding has given rise to some of the best and most consistent cannabis in the world.

When to Use Liquid Fertilizer for Cannabis

Your liquid feeding schedule depends on the type of cannabis garden you’re raising. If you’re running a hydroponic setup, you will regularly expose your roots to nutrient-rich solutions.

On the other hand, if growing in soil, you should liquid feed every other watering–if not less–depending on the complexity of your soil. At the very minimum, you might only liquid feed a few times throughout their growth until flowering has started.

In the final two weeks before harvest, only give your plants water to help the plants remove the nutrient buildup in the buds.

Just as important as knowing when to liquid feed is knowing when not to administer nutrients. In the final two weeks before harvest, only give your plants water to help the plants remove the nutrient buildup in the buds. This process, which leads to a cleaner smoke, is called “flushing.”

Avoid liquid feeding if your plants do not appear to be taking in the nutrients. This is known as a nutrient lockout and it occurs when the plants have been overfed; due to salt buildup, they are unable to take in any new nutrients.

How to Liquid Feed Cannabis

Like all other types of feeding, there are a few rules and tips to follow to ensure you are liquid feeding properly.

Choosing Nutrients

Deciding which fertilizers to use can be a difficult choice as liquid nutrients are often very expensive and confusing to understand.

All nutrients offer the nitrogen-phosphorus-potassium (NPK) ratio, which is shown as three numbers. These are the primary nutrients needed to grow plants. However, what a cannabis plant needs during its vegetative cycle is different from what it needs while flowering. A general rule of thumb is that a vegetative fertilizer should have high nitrogen, low phosphorus, and moderate potassium. An example would be an NPK ratio of 9-4-5. As a plant transitions into flowering, taper off the nitrogen and focus on phosphorus and potassium–seek a ratio around 3-8-7, for example.

Finding the best nutrient products for you will take time. Speak with your local store for recommendations to get started, but remember that spending the most money and buying all the products does not guarantee success.

Browse Nutrient Solutions on Leafly

How Much Liquid Fertilizer Does Cannabis Need?

Properly feeding your plants requires careful monitoring. Many growers start at a lower solution dose than recommended and work their way up until the plants respond optimally.

Some find that their plants thrive at a lower dose while others achieve the same results with more nutrients. The key is to be observant of your garden and pay attention to how the plants respond to fertilizer. Too little food and the plants will have stunted growth, while too much food can lead to nutrient burn and lockout.

Simple and versatile, it comes as no surprise that liquid nutrient solutions are so popular among cannabis growers. Liquid nutrients can be pushed through drip lines, misters, and hoses for easy and efficient delivery.

Although liquid fertilizers may be the only input your plants need, be sure to also familiarize yourself with the other feeding methods discussed in this series.

Liquid feeding is a great method of delivering nutrients to your plants. Learn more about how to use this method to grow cannabis.