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How to Use Liquid Nutrients for Cannabis Plants

March 20, 2018
Liquid 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.


What are the best nutrients for growing cannabis?

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.


How to Grow Hydroponic Cannabis

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 and when to flush cannabis plants

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.


What Is a Feed Chart and How Can It Improve Your Cannabis Garden?

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.


What Is Nutrient Lockout and How Does It Affect Cannabis?

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.

Lead image by Leafly

Trevor Hennings's Bio Image

Trevor Hennings

Trevor is a freelance writer and photographer. He has spent years in California working in the cannabis industry.

View Trevor Hennings's articles

3 part series

  • kelso

    Liquid fertilizer is not organic. If it comes from a bottle it’s not organic. Best to use natural amendments. Blood Meal, Kelp Meal, Alfalfa Meal ect. . And a few others also.

    • Soil Doctor

      I’ve never seen a more incorrect statement on the internet.

      • tweb

        I would agree with you on “Liquid fertilizer is not organic. If it comes from a bottle it’s not organic.” But not the 2nd half.

      • Anthony Joseph Gomes

        been on here long soil doctor? there are some real prodigies who get handed a computer.

    • eric3564567

      The statement is both correct and wrong. While it is not most true method of organic gardening, they do make ORGANIC or natural liquid fertilizer. Liquid vs granular feedings both have advantages and disadvantages. A lot of liquids are not truly of organic ingredients.

    • Mike Somewhere

      Nitrogen is Nitrogen they are both the same chemical. We do not have 2 periodic table of elements (one for organic/one for non organic) because Nitrogen is just that…it is the same stuff. Biggest racket going is Organics IMO.

      • Sara Hardwick Mays

        I agree, technically every “living” thing is organic, isn’t it! I mean it’s all one organism or another… and an element is an element there are no multiple strains of hydrogen or oxygen or nitrogen etc…

        • Gerald Dixon John Cummings

          Anything that is a based on the element carbon is considered to be “organic”. Chemistry

          Organic matter, matter that has come from a once-living organism, is capable of decay or is the product of decay, or is composed of organic compounds

          Organic compound, a compound that contains carbon

          Organic chemistry, chemistry involving organic compounds

          Just sayin’.

    • Anthony Joseph Gomes

      did you flunk science kid?

      • Christopher Rigos


    • Christopher Rigos

      I use liquid fox farm and all 3 bottles are organic and I feed my plants every week so far they are doing great

  • Ed Svetlik

    I am very confused now about liquid fertilizer are not organic I am using sensi grow a + b for veg and part of it is not organic . I all so use bone meal blood meal and kelp in my soil along with worm casting if I can afford them . I recently got a mentor and he uses dr. Earth soil and mixs 1/3 perlite and he says that’s all you need and I have fertilized just a few times and he tells me to do it with mollassas . One time I did it with out talking to him first and I over fertilizing them had to flush them out and it took a couple of weeks to recover and i used to water 2 times a week water one day the next time fertilize and I think now every thing I was doing was wrong I allway grew airy bud . I am looking at the container and I don’t see anything that says it’s organic but when I look in my grow book for organic fertilizer it has names like fox farm , sensi grow , ect. This is what is in mine total nitrogen 3 percent 3 percent nitrate nitrogen calcium 3 percent dirived from calciam nitrite magnesium nitrate so I am wonder part part is not organic

  • Stephen 49

    How soon should seedlings be fertilized?

  • Juan Bonet

    I make my own fertilizer with a little bit of urine,water,tea compost,and a little bit of milk works great, however I am seeing a little bit of nutrient burn on it,so I will lower dosage and use only water tommorow I just don’t trust chemicals my grow is all organic and I even make my own soil.