Using organics is also great if you want to be more in-tune with your natural environment. Organic fertilizers are readily available from renewable sources and are an earth friendly option.
The fertilization process can repeat itself year after year as the soil continually improves—next year, your soil will be even better than this year’s.
Liquid nutrients are typically used for indoor growing, but can be used outdoors too. Liquid nutrients are used for weed plants in soil, hydroponics, and other grow media, and can be pushed through drip lines, misters, and hoses for easy and efficient delivery.
There are many different cannabis nutrients out there and it may be overwhelming knowing where to start. Here’s a breakdown on some of our favorites.
The tea can be applied to roots or as a spray on leaves of your cannabis plants. Dilute the tea with water at a ratio around 1:20 when applying it to roots. A basic tea can’t harm or burn your plants, so you can apply a potent dose freely. As a foliar spray, compost tea is generally diluted with water at a 1:2 ratio.
How to make compost tea for marijuana plants.
However, the benefits of compost tea are debated in the agricultural world. Many gardeners report quality results when using it, while others see no more benefit than applying straight compost. The uncertainty lies in whether or not growing and developing populations of microorganisms in the tea can actually benefit plants and prevent disease.
Compost is filled with beneficial microorganisms and nutrients, and you can take it one step further by steeping it in aerated water. This process, called “compost tea,” extracts the microorganisms and soluble nutrients into a water “tea” solution.
Potassium has a number of jobs that largely help regulate the systems that keep a plant healthy and growing. It plays a large role in osmoregulation, the passive regulation of water and salt concentrations in the plant. Potassium accomplishes this by controlling the opening and closing of the stomata—the pores in the leaves—which is how a plant exchanges CO2, H2O, and oxygen.
Compost tea should never be a 100% replacement for nutrients, but it can be a great complement to other nutrients.
When applied to soil, you’re adding to the soil food web by introducing a healthy population of microorganisms that are aerobic in nature. These organisms hold nutrients, aerate soil, aid water retention, increase nutrient absorption in the cannabis plant, help grow healthy roots, and help prevent diseases.
We recommend these organic fertilizers:
Because liquid nutrients are readily available to a cannabis plant’s roots, they are fast-acting, meaning they can damage plants if you feed them too much.
Indoor growers typically use liquid nutrients and mix them in with water before watering plants. Using liquid nutrients is usually more time consuming, as you typically have to measure and mix them in water 1-2 times a week.
Products are also generally divided into “grow” solutions, high in nitrogen needed for vegetative growth, and “bloom” solutions, high in phosphorus for flower development. You can stick to these general terms if you don’t want to get bogged down with numbers.
A general rule of thumb is that a vegetative fertilizer should have high nitrogen, low phosphorus, and moderate potassium: for example, 9-4-5. As a plant transitions into flower, taper off the nitrogen and focus on phosphorus and potassium—seek a ratio around 3-8-7, for example.
Compost tea recipe for marijuana plants.
You’ll also need a 400-micron mesh bag to place ingredients for the tea. While you can buy pre-built tea brewers, you can also easily make your own for cheap.
We recommend not using nutrients made for indoor growing for outdoor plants, as they are usually composed of synthetic mineral salts and can damage soil bacteria.
Nutrient solution bottles and fertilizer bags will indicate how much of the three main nutrients are in the product, in the form of N-P-K: Nitrogen, phosphorus, and potassium, For example, a product that says “10-4-4” will contain 10% available nitrogen, 4% phosphorus, and 4% potassium by weight.
Commercial soil blends also exist that already contain the proper mix of these nutrients.
Cannabis plants need different amounts of these nutrients throughout the different stages of growth: more nitrogen during vegetative growth, and more phosphorus and potassium during flower for bud production—also called “bloom” nutrients.
You can add compost tea to weed plants by:
Organic fertilizers and nutrients can be more forgiving than liquid nutrients. They usually contain less immediately soluble nutrients and more elements that are beneficial to soil organisms.
Growing high-quality weed requires more nutrients, or fertilizer, than most common crops.
Your marijuana plants need the following primary nutrients, collectively known as macronutrients:
A healthy compost tea pulls soluble nutrients and microorganisms from compost, including bacteria, fungi, and protozoa.
When using liquid nutrients for cannabis plants, it’s important to have a watering schedule to write down and track:
Potassium also triggers the production of ATP, which works to store energy produced in photosynthesis by creating glucose. This glucose is then used as energy for the plant as it grows. Without sufficient potassium, you will see weak plants starved for energy that appear burnt because they are unable to successfully regulate the exchange of CO2, H2O, and oxygen.
When creating a first batch of tea, keep the solution simple. If you use city water, allow it to sit and breathe so chlorine can break down. Once your tea is brewing, keep it out of direct sunlight and make sure the air pump is running and oxygen is being pushed through the water.
Tea brewing takes time, so it’s important to figure out when you want to apply the tea. Most teas generally take 24-36 hours to brew. You don’t want to let your tea brew for too long because the microorganism populations will develop to a point where they won’t have enough oxygen or space to live, and will begin to die, which can damage your tea.
To use liquid nutrients, you’ll need a separate water tank, such as a dedicated garbage bin, to mix them into water. You’ll also need to know how much water is needed for all your plants. Depending on the amount of water you need, add the correct ratio of liquid nutrients according to the bottle’s directions.
Although you want to avoid discolored leaves for most of the flowering stage, it’s normal for leaves to start turning yellow the week before harvest.
Major Deficiencies May Appear if You Don’t Add Nutrients.
Simple Duos – Use one bottle for the vegetative stage, and the other bottle for the flowering stage.
Multiple bottles at a time – Typically there are 3 bottles for the base nutrients but sometimes only 2. This class of nutrients needs all bottles at all times, which get mixed in different ratios depending on the stage of life. More flexibility to alter ratios throughout the plant’s life.
How to Add Nutrients:
Recommended Soil Nutrients.
I gave the plant extra “bloom” nutrients (using the GH Flora trio). This reversed the yellowing and buds continued fattening. Here is that plant at harvest.
Organic cannabis growing is rewarding!
Soils Starts Running Out of Nutrients.
How to Adjust pH in an Organic Soil Grow (regular PH Up and PH Down can harm the natural balance of the soil)
If using filtered or RO water (which contains few micronutrients) it’s a good idea to also add a Calcium/Magnesium supplement by the same brand that makes your base nutrients. Cannabis plants go through a lot of Calcium and Magnesium!
Best supplement ingredients for organic growing.
Seedlings Have Plenty of Nutrients in Any Soil.
Test and adjust the pH of your water to get faster growth and prevent nutrient deficiencies in soil.
My favorite organic supplement contains all: Floralicious Plus.
Recommended Mineral-Based or Synthetic Soil Nutrients – This isn’t a comprehensive list of great cannabis nutrients, but these are the nutrient system I have experience with and recommend for growing cannabis.
Summary of a Marijuana’s Nutrient Needs in Soil.
You can’t go wrong with the Fox Farm trio for soil. Just follow the instructions on the label at half-strength for cannabis plants.
Dyna-Gro Grow + Bloom is my favorite simple nutrient duo.
Just about any soil potting mix contains enough nutrients for seedlings.
Now that you’ve seen some suggested marijuana soil nutrients, let’s go through a quick overview of a cannabis plant’s life in soil as it relates to nutrient needs.
How to Adjust PH Using Synthetic Nutrients.
Organic Soil Nutrients.
There used to be a ton of organic soil nutrients in bottles (like the now-discontinued GO Box) but many options have disappeared as growers switch to using amended compost for their organic nutrient needs. Why? The organic nutrients in bottles get similar results to mineral nutrients. The biggest difference in organic growing seems to come from using actual compost and/or amended soil.
This flowering cannabis plant has several weeks before harvest, but it’s already losing bottom leaves and turning pale all over. This means the plant wants higher levels of nutrients overall. Without enough nutrients, more leaves will turn yellow and buds will stop getting bigger.
With many soil mixes, plants run out of nutrients and start growing slowly after a few weeks. When a plant looks lime green all over (especially if bottom leaves are turning yellow and falling off), it needs more nutrients overall. The left plant received plain water and started turning yellow after the soil ran out of nutrients. The right plant has been receiving nutrients in the water and is a nice healthy green color.
Soil is so simple. So close to nature. Add seeds, remember to water your plants, and wait for an awesome harvest, right? Unfortunately, many growers run into problems with cannabis plants in soil. The culprit is almost always either your environment, watering habits, or nutrients/supplements. We’ve covered environment and watering habits already, so this cannabis soil nutrient tutorial will focus on which soil nutrients and supplements you need to get the results you want.
Alternative: Create a “reservoir” of nutrients under the soil (“just add water” setup )
Other trace minerals thought to be essential include cobalt (Co), silicon (Si), chlorine (Cl), and selenium (Se). Not all sources agree on their inclusion in the essential group, though they are important to support all plant life.
Essential Macronutrients The group of nutrients needed in large quantities by plants is collectively known as macronutrients. Some of these are provided by the environment, while others are provided by or need to be added to the soil.
These secondary essential nutrients perform a wide range of critical functions to proper cannabis development. They are often necessary components or complementary parts to other nutrients and functions. They are all needed for plant and root growth, but they do have specific roles. Calcium assists in transporting other nutrients and aids in their absorption. Magnesium is a critical component of chlorophyll. Sulfur aids in the transport of chlorophyll, but also assists with plant metabolism and transpiration. The lesser amount required to aid in the proper growth and development of healthy cannabis should not be mistaken as being less important than the micronutrients. The same can be said for the diminutive amounts of micronutrients needed.
What follows is an oversimplification of the exact roles of each nutrient (in some cases, we still don’t know what all essential nutrients do and how exactly they interact with one another). Nitrogen is needed for the development of foliage and the production of proteins. Phosphorus is critical for root, flower, and seed development. Potassium is a requirement of overall plant health and aids in water absorption.
pH and Nutrient Availability As important as nutrients –if not more so– is the pH of the soil or media the cannabis is growing in. The pH is a measure of the acidity or alkalinity of soil or growing medium.
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All plants, including cannabis, require certain essential nutrients to grow healthy, strong, and productive. From essential macronutrients to secondary nutrients and micronutrients, find out how much you need of each.
Cannabis needs different amounts of essential macros depending on the stage of development. Nitrogen is needed in higher quantities during the vegetative and bud-forming stages than during the flowering stage.
For its part, phosphorous is needed more during the flowering stage and is only required at about half the ratio of N levels during the vegetative phase of development. During this phase, K is needed at between half and two- thirds the level of N.
They do, however, need to be in a significantly higher quantity than the micronutrients, so they are separated here. The essential secondary nutrients are magnesium (Mg), calcium (Ca), and sulfur (S). These nutrients are often unavailable to cannabis if proper pH levels are not maintained (more on that later).
What does this have to do with the essential nutrients needed for growing cannabis? Nutrients may well be present in sufficient amounts to support robust growth and plant function, but they can be locked out or otherwise made unavailable to the plant. The ideal pH range to try to maintain for cannabis is generally accepted to be in the 6.0 to 6.5 range, with some variation depending on media selected. To determine pH, make sure to perform a soil analysis.
No matter what source, boron (B), manganese (Mn), zinc (Zn), copper (Cu), iron (Fe), and molybdenum (Mo) are always listed as essential micronutrients. Like the other essential nutrients, all micronutrients either have a unique function or serve to assist in the functions and processes of the other nutrients.
The other macronutrients that are needed and can be added to soils or other media are nitrogen (N), phosphorus (P), and potassium (K). Most commercial formulations of dry or liquid fertilizers will have three numbers on their packaging. These three numbers refer to the percentage by volume of N, P and K. Each of these individual essential nutrients performs a different –but vital– function to cannabis plants.
Soils or other media with a pH of less than 7.0 are acidic; soils or other media with a pH greater than 7.0 are alkaline. The pH scale is exponential, with each number representing a factor of 10 times greater or less than the number next to it. For example, a pH of 6.0 is 10 times more acidic than a pH of 7.0, and 100 times more acidic than a pH of 8.0.
Provided by air and rain, Oxygen (O), hydrogen (H), and carbon (C) are sometimes excluded in discussions of essential nutrients. This is because they are not elements that are often lacking, despite being needed in large amounts. They are also not ones that are components of any fertilizer or commercially-available nutrient package.
What follows is not an exhaustive list, but a sampling of some of the roles of micronutrients and how they aid in the development of cannabis plants:
Essential Micronutrients The number of micronutrients listed as essential can vary based on the source. Like secondary nutrients, it is somewhat a matter of classification as some list the secondary nutrients as micronutrients. Either way, they represent minerals and elements that are not as abundantly available on Earth and as such are not needed in very high amounts by cannabis plants, but are still necessary.
A nutrient is considered essential when it meets certain criteria. It must be directly involved in plant nutrition, be a vital component to the plant’s life cycle such that without it the plant would die or not be able to perform one or more of its necessary functions, and it must be unique enough that no other nutrient can replace it or perform the same function. Let’s examine which nutrients found in nature are essential for the cultivation of top-shelf cannabis. These vital nutrients can also be found in organic fertilizers.
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Soil testing can be a simple do-it-yourself procedure or can be done by a reputable lab. It’s a routine procedure and is relatively inexpensive either way. A soil testing DIY kit costs only a few dollars and involves sending a smart amount of soil or growing media to a private or university-owned lab. Within a few days to a week, you will receive a detailed report with your soil’s current nutrient levels, along with the percentage of organic matter, and other relevant information. Doing this test can help you make the necessary adjustments to ensure your cannabis as what it needs to thrive.
Essential Secondary Nutrients Some sources do not separate the secondary nutrients and instead lump them in with the macronutrients since they aren’t needed in the same high quantities as the macronutrients.
Cannabis has thousands of unique properties, but like any other plant, it requires the same essential nutrients to properly grow and produce the desired yield of buds. Plants need relatively large amounts of macronutrients, lesser amounts of secondary nutrients, and small to trace amounts of micronutrients to germinate, grow, flower, and produce seed. All told, there are about 20 essential nutrients needed for optimal cannabis growth and development.
Source: Maximum Yield, September 23, 2019.
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