Which Nutrients Are Best For Growing Cannabis?
Table of Contents
What’s the difference between nutrients?
If you’ve decided to start growing cannabis for the first time, trying to figure out the best nutrients for your setup can be very confusing. There are many nutrient companies, and each company creates multiple lines of nutrients and supplements for different purposes.
The abundance of cannabis nutrient options can be overwhelming
As a cannabis grower, your goal is to give your plants the right amount of nutrients at the right time. There are two main life stages for cannabis plants (vegetative stage and flowering stage). Each stage has different nutrient requirements. Luckily, many nutrient companies make great products even though they’re all using different formulas and techniques. Here’s how they differ:
- Nutrient Ratios – Each brand has different nutrient ratios they believe are optimal for each stage of growth.
- Ingredients – There are many different combinations of chemical and organic compounds that can add up to the same nutrient ratios. Each compound reacts differently with each other. This means you can see two nutrient bottles with the exact same NPK ratios on the bottle, but they will provide somewhat different levels of nutrients to your plants. The ingredients determine whether nutrients are considered organic or synthetic.
- Designed for Soil or Hydro – It’s really important to match your growing medium with your nutrients. “Soil” nutrients are different from “Hydroponic” nutrients so make sure you’re getting the right kind! Coco coir is generally considered a type of hydroponics when it comes to nutrients, though there are also nutrients specifically designed for coco coir. Typically, hydroponic nutrients contain everything a plant needs to grow and can be used in any grow medium.
Important Tips on Cannabis Supplements
- Don’t confuse supplements for nutrients. If the NPK ratios printed on the front of the bottle are really low (like 0.2-0.2-0.1) it means that this product is some type of supplement. Base nutrients provide all the necessary NPK and micronutrients for healthy growth, so supplements are not necessary for plants to thrive. Some supplements are helpful, but going overboard may cause unwanted reactions or burn your plant. Do you need supplements to grow great weed?
- Use nutrients and supplements from the same company to minimize unexpected interactions. Combining nutrients and supplements from different companies greatly increases the chance of unhappy plants! It’s also a good idea to only add one new supplement at a time and watch how plants react before adding anything else new or different. If this is your first grow, try to pick just one or two supplements that appeal to you. It’s easy to go overboard. Nutrient companies will happily sell you supplements you don’t actually need.
Now that you understand the basics, are you ready to learn how to figure out the best marijuana nutrients for your setup?
Examples of Good Can nabis Nutrients
Here are several examples of trustworthy nutrient brands that work well for growing cannabis. These nutrients have been extensively tested by real marijuana growers and are known to produce great results!
- General Hydroponics – Soil, Coco Coir & Hydroponics
- Fox Farm – Soil & Coco Coir
- Botanicare – Soil & Hydroponics
- House & Garden – Soil, Coco Coir & Hydroponics (lately it’s been difficult to find certain H&G products online)
- Canna Coco – Coco Coir
- Dyna-Gro – Soil, Coco Coir & Hydroponics
Honorable Mentions – I haven’t tried these nutrient brands yet, but they are popular for growing cannabis
General Hydroponics Flora Trio
General Hydroponics offers a simple duo with one bottle for the vegetative stage, and one bottle for the flowering stage called FloraNova Grow + Bloom. This nutrient system is cheap, simple, and easy with excellent results in soil/coco/hydro. The biggest issue I have with the duo is the liquid is so thick it can be annoying to measure out.
However, their Flora trio is a winner. A tried and true favorite of mine, the Flora trio works very well for growing cannabis. I’ve had great success with it in every grow medium including soil, coco coir, and hydroponics. I used this nutrient system for almost a decade and have always been thrilled with the results. I’ve been testing new nutrient systems so I can report back to our readers like you, but based on my years of success I know you’ll be happy with the Flora trio. Best for…
- Coco Coir
·Soil or Coco Coir
Follow the instructions on the side of the bottle at half-strength for great results in soil or coco. It’s recommended to also use a Cal-Mag supplement if using filtered water, growing in coco, or using and LED grow light (all tend to increase the Cal-Mag needs of your plant). I prefer the GH version called CaliMagic, and use at 1 tsp/gallon.
·Hydroponics / DWC/ Bubbleponics
Use similarly to soil or coco, just make sure to also get Hydroguard to protect your hydroponic roots from root rot.
Check out a few different grow journals featuring the GH Flora trio
Fox Farm Nutrient Trio
The FF trio is a popular nutrient system for cannabis growers that contains a variety of natural sources for nutrients like earthworm castings and bat guano, which cannabis plants thrive on. Fox Farm nutrients contain too much organic matter for DWC/hydro (increasing the chance of root problems), but all that organic matter is great for plants in a hand-watered environment to enhance smell and flavor of your finished product. Best for…
- Coco Coir
Very concentrated, less is more. “Grow Big” & “Tiger Bloom” provide most of the major nutrients your cannabis needs, while “Big Bloom” has many micronutrients and beneficial compounds that help nutrient uptake and root health. This trio works extremely well by itself, just follow the feeding schedule (here’s a PDF, here’s a JPG) from Fox Farms at half-strength to start.
Check out a grow journal using the FF trio for Soil!
Use the “hydro” version of Fox Farms nutrients when growing in coco coir. Two bottles are the same as the soil trio, but the “Grow Big” bottle is formulated slightly differently for a soilless grow. Follow the feeding schedule (here’s a PDF, here’s a JPG) from Fox Farms at half-strength to start. Generally, the Fox Farms nutrient system will prevent Cal-Mag deficiencies, but it’s good to have extra Cal-Mag on hand just in case whenever growing cannabis in coco coir, if using filtered water, or if growing with LED grow lights.
Botanicare is a great company that’s been around for as long as I’ve been growing, and whose supplements I’ve been using for years (specifically, their Hydroguard supplement is the most effective thing I’ve used to prevent root rot in a hydroponic setup). Best for…
·Soil version (Organic)
Use “Grow” in the vegetative stage, and “Bloom” in the flowering stage. Organic. Claims to be usable in hydro, but I’ve only seen growers use it in soil so that’s what I’m recommending it for 🙂
Get the trio: Grow, Bloom, Base (need all 3 bottles for all phases of growth)
The three bottles are all that’s needed to get your plants successfully to harvest time, just follow the feeding schedule from Botanicare [PDF], starting at half the recommended strength. Hydroguard is an important root supplement that will help prevent your plant from getting root rot in a hydroponic reservoir. The KIND series has been highly recommended by several hydro growers I know in real life and they make some very useful supplements.
From a grower: “Botanicare KIND is like the opposite spectrum [of the Botanicare Pure Blend series]. The Base is just Nitrogen and Calcium. Grow and Bloom both have most of the minerals in them, along with things like sea kelp. The Bloom is also 0-6-6. Grow at 2-2-4. So quite literally you can call the shots on Nitrogen and Calcium. That level of control hasn’t been around a great deal in our market. For the savvy grower, this is a pretty nice tool.”
House & Garden – Often difficult to find online!
The House & Garden lineup is an expensive but effective line-up. From a grower: “H&G was started by a top researcher from Canna. They are right outside of Amsterdam and because cannabis is legal there, so both Canna and H&G are able to do R&D using cannabis. I don’t know about Canna, but I know that House and Garden makes all their own nutrients in-house and they work great.”
The biggest downside of House and Garden (besides price) is it’s getting harder to find online. This brand is often best purchased in person at a hydro store. Get a custom nutrient schedule directly from the people at House & Garden via their free online nutrient calculator.
Name of base nutrients for…
- Soil – Soil A + B
- Coco Coir – Coco A + B
- Hydroponics – Aqua Flakes A + B
- Recommended supplements: Roots Excelurator, Algen Extract,Bud XL, and shooting powder
This plant was grown using the House & Garden Line-up (A+B as base nutrients, plus the supplements Roots Excelurator, Algen Extract, Bud XL, and shooting powder)
Canna Coco is a very popular company for pot growers. Their nutrients have been specifically designed to grow cannabis in coco coir (as you may be able to tell from the name).
- Best for Coco Coir
This combo is a crowd favorite – many coco coir growers write in to tell us this is their favorite cannabis nutrient for growing in coco coir. Get a custom nutrient schedule from Canna or use this pre-made one [JPG].
From a grower: “Canna is a Dutch company and one of the best IMO. They make a great product line for growing in coco coir and test their products on real cannabis plants.”
Another grower said, “Canna products are one of the only nutrient lines to be developed primarily for cannabis (and tested on live plants). They’ve been doing so for almost 30 years. Cost is a little higher than competitors but worth every penny.”
A different grower added, “Canna – I have only used their coco line, but it is the highest quality you will find.”
Originally designed for orchids, Dyna-Gro nutrients have proven to work exceptionally well for cannabis plants. If you want professional results without spending a ton of money or having to mix multiple bottles together, this combo give your plants everything they need from seed to harvest. Dyna-Gro nutrients are suitable for any growing medium including soil, coco, or hydro.
- Best for Soil, Coco or Hydroponics
Dyna-Gro Grow + Bloom – Use “Grow” in the vegetative stage and “Bloom” in the flowering stage.
Dyna-Gro Grow + Bloom is my recommended nutrient system for newbies. One bottle for veg, one for bloom. Super simple!
One Last Tip…
When using a complete nutrient system like the ones listed above, always start at half the recommended strength by the manufacturer, and only increase nutrient levels if your plant is getting pale. If you’re giving too low levels of nutrients, the entire plant will start to appear overall pale or lime green. If you have a different nutrient deficiency (diagnose your plant here), chances are it’s caused by incorrect pH, not by too-low levels of nutrients.
It’s a good idea to always start at half the manufacturer’s recommendation ! Most nutrient companies recommend way too much for growing cannabis!
Why not keep adding more and more nutrients? Doesn’t more equal better? No, nutrients are more like a multivitamin than food. After your plant has enough nutrients, adding more gives you diminishing returns, and too much starts causing the following problems.
A cannabis plant turns pale all over (left) when it needs higher levels of nutrients overall. If plant is a healthy green (right), stick to half the recommended dose.
Too high levels of nutrients causes…
- Nutrient burn – nutrient burn causes tips of leaves and edges of buds to appear burned. It isn’t a huge deal but doesn’t look as pretty, especially if it gets bad enough to spread to your buds.
- Random nutrient deficiencies and lockout
- Buds don’t grow as big as they could have in the flowering stage, especially if levels of Nitrogen are too high
- Leaf discoloration may spread to the sugar leaves on the buds (not a big deal, but not pretty either)
Now that you understand everything you need to know about picking the right nutrient system, check out some supplements!
Learn About Cannabis Supplements:
What’s the Best NPK Ratio for Cannabis Nutrients?
For the best results, your cannabis needs the following nutrient ratios…
Where is this information? Most nutrient bottles display 3 numbers, often called N-P-K, which stands for Nitrogen, Phosphorus and Potassium
Why “K” for Potassium? The atomic symbol of Potassium is “K” from Neo-Latin kalium.
In other words, you want to use a “Vegetative” (high Nitrogen) or “general purpose” nutrient formula for the first stage of life known as the vegetative stage. If using high-quality soil, you can skip vegetative nutrients for the first 3-4 weeks while your plant uses up the nutrients in the soil, otherwise, you should start with vegetative nutrients around the time your plant opens its first leaves.
Use a “Bloom” (low Nitrogen) nutrient formula with plenty of P & K for the flowering stage. Start using bloom nutrients when buds start forming to make sure your plant gets plenty of Phosphorus & Potassium, which are crucial to bud development.
Phosphorus tends to increase the number of flowers, while Potassium helps increase the bulk/weight of flowers. Be careful, though because going overboard with either one can burn your plants!
The main thing is to avoid giving too much Nitrogen in the flowering stage, as it can discourage bud development and add an unpleasant taste to buds, which is why a general-purpose plant nutrient isn’t a good choice in the flowering stage.
In a pinch, nutrients for Shultz “cactus” or “succulents” can be used in the flowering stage until you get better nutrients because it contains low amounts of N and plenty of P & K.
Note: Don’t use any type of non-organic time-released nutrients (like fertilizer spikes, or “slow-release” Miracle-Gro soil) because they deliver too much N in the flowering stage and may reduce bud growth.
Cannabis needs plenty of P & K to make buds in the flowering stage!
The Best Cannabis Nutrients Aren’t Enough! Check the pH of your water to plants to prevent nutrient deficiencies
It may surprise you that the most common reason growers get nutrient deficiencies is because the pH is too high or too low. This happens even if the right amounts of nutrients are present because your weed simply cannot absorb the nutrients if the pH isn’t in the correct range.
Optimum cannabis pH for..
Soil: 6.0 – 7.0
Coco Coir: 5.5 – 6.5
Hydroponics: 5.5 – 6.5
Checking the pH will make a huge difference to your grow by keeping plants vibrant and healthy. It only takes a few minutes each time you water your plants! If you get a digital pH pen, it only takes seconds to test your pH!
Organic vs Chemical (Synthetic) Nutrients
This is a common question we get at Grow Weed Easy: Are organic nutrients better than chemical nutrients? It’s not a matter of which one is better, because they’re good at different things.
- Bud Smell & Taste – Many growers believe organically grown cannabis will create the most fragrant and “smoothest” buds. Some of the best benefits to smell and taste seem to come from using composted soil that’s been amended with nutrients from natural sources. This creates a living soil with colonies of beneficial microorganisms and is often associated with a bolder taste and smell in buds. However, watering your plants with liquid nutrients that just happen to be organic tends to get results similar to synthetic or mineral-based nutrients. It seems to be the soil that makes the difference when it comes to organic growing.
- More Natural – Especially when growing in a living soil, you’re creating a home for your roots that is as close to nature as possible (only better because you’re making sure your plant gets everything it needs!)
- Not for Hydroponics – Organic nutrients are not the best choice for hydroponic systems because any organic matter can cause unwanted stuff to grow in your reservoir. It’s possible to grow organic hydro but let me just say this: as of yet, I’ve never seen organic hydroponics go well for someone, though I wouldn’t mind being proven wrong 😉
Recommended Organic 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.
- Nature’s Living Soil (super concentrated organic compost nutrient mix) – amend bottom 1/3 of your plant container with this special organic amendment, and plants will be able to slowly use the nutrients “on-demand”. Even if your plants are already growing in soil, you can sprinkle a little of this on top of your soil and water to deliver organic nutrients. Note: smells strongly of manure!
- Dr. Earth Organic Nutrients – dry nutrients
- Vegetative Stage: Homegrown Tomato, Vegetable & Herb Fertilizer (better) or All-Purpose Fertilizer (good)
- Flowering Stage: Flower Girl Bud & Bloom Fertilizer
- Roots Organics Terp Tea Fertilizer Set (Grow & Bloom) – This dry formula is mixed with aerated water and brewed for 24 hours to create a “tea” for your plants. Can also be used as a top dressing.
Best supplement ingredients for organic growing
- Sea kelp – a source of K, helps plants resist heat and stress
- Leonardite – full of humic acids for happy roots, resist stress
- Protein hydrolysate (contained in many supplements) – helps plants produce big roots and be more resistant towards water stress
- Potassium Sulfate (also called “Sulfate of Potash”) – the sulfur and potassium promote smells and bud development in the flowering stage
My favorite organic supplement contains all of the above: Floralicious Plus
How to Adjust pH in an Organic Soil Grow (regular PH Up and PH Down can harm the natural balance of the soil)
Organic cannabis growing is rewarding!
Chemical Nutrients (including synthetic and mineral-based nutrients)
- Possibly Increased Potency – While organic nutrients may increase the smell and taste of buds, chemical nutrients tend to increase the potency.
- Faster Growth and Bigger Yields – Synthetic nutrients provide nutrients to plants in the most easy-to-absorb forms possible. This results in somewhat faster growth and improved yields since the nutrients don’t need to be broken down in the soil by a colony of microorganisms before they become available to your plant.
- Only Choice for Hydro – These are the best cannabis nutrients for hydroponic systems because they are less likely to cause stuff to grow in the water reservoir. However, chemical nutrients can also be a great choice for soil or coco because of the increased potency and faster growth!
- Easier to Get Nutrient Burn – Although you can give cannabis plants nutrient burn with organic nutrients, it’s much easier to give them nutrient burn with chemical nutrients. This is due to the easily absorbable nature of these nutrients. Synthetic nutrients get taken up by your roots whether the plant needs them or not.
The General Hydroponics Flora trio is a synthetic nutrient that’s so effective it was used by NASA to grow plants in space!
Don’t want to use nutrients at all? Learn how to compost your own super soil (or buy super soil pre-made online)! Super soil compost contains all the nutrients your plant will need from seed to harvest so you just need to add water. As an added bonus, with composted super soil you rarely need to worry about maintaining your pH. Instead, the composting process develops a colony of microorganisms in your soil that will automatically take care of the pH for your plants to an extent (like in nature), while slowly providing nutrients on demand.
Super soil compost has been amended so no additional nutrients are needed. Just add water!
Can I create my own nutrient system?
Creating a nutrient system is more complicated than just adding “Nitrogen,” “Phosphorus” and “Potassium” plus all the various micro-nutrients in certain ratios. There several different chemical compounds that provide each of these nutrients and they’re not all equal.
What's the "best" cannabis nutrient system? There are literally thousands of choices! Learn what to look for and get examples of great marijuana nutrients.
How to use nutrients and fertilizers for growing marijuana plants
A cannabis plant needs many nutrients, and pulls these from the soil. Left on its own, with good soil, plenty of light and water, and a temperate environment, a weed plant will grow fine, but nutrients will help the plant thrive and grow healthy and strong.
What are cannabis nutrients?
Growing high-quality weed requires more nutrients, or fertilizer, than most common crops.
Outdoor cannabis growers typically add powdered nutrients to soil when transplanting a weed plant outside. This will give the plant all or most of the nutrients it needs for its entire life cycle, and if you want to add more nutrients to plants later, you can add them to the top of soil—called “top dressing.”
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.
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.
What nutrients does a cannabis plant need?
Your marijuana plants need the following primary nutrients, collectively known as macronutrients:
- Nitrogen (N)
- Phosphorus (P)
- Potassium (K)
These micronutrients are needed as well, but in much smaller quantities:
Additionally, cannabis plants derive these non-mineral elements from air and water:
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.
Nitrogen is mainly responsible for a cannabis plant’s development during the vegetative stage of its life. It’s an essential part of chlorophyll and without it, a plant can’t turn sunlight into energy and it won’t be able to grow.
Nitrogen is also part of amino acids that act as building blocks for proteins in a plant. Without the necessary proteins, your cannabis plants will be weak and frail. Nitrogen is also a part of ATP, which allows plant cells to control the use of energy.
Nitrogen is also necessary to create nucleic acid, an essential ingredient in DNA or RNA, and without it, cells won’t be able to grow and multiply.
Phosphorus is important for producing large, healthy buds. The key role of this element is to help make nutrients available for the plant to uptake. These nutrients are used to build the structure of a plant as it grows from its roots to its flowers.
Without adequate phosphorus, marijuana plants will show signs of undeveloped roots and might not even flower. Early signs of phosphorus deficiency shows up as a purple hue in the veins of leaves.
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.
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.
Calcium is responsible for keeping the structure of cell walls in a plant together. Without calcium, new growth won’t develop properly and the plant won’t function as it should. New growth will be stunted, leaves will curl, and rusty spots will show up on the plant.
Magnesium acts as the central molecule in chlorophyll and without it, plants aren’t able to generate the glucose from photosynthesis. No magnesium means no energy can be converted from sunlight.
Once magnesium has helped create glucose, it helps metabolize glucose to make it available for the plant to grow. Without sufficient magnesium, you will find yellowing leaves, with discoloration reaching the veins as well.
How to use and mix cannabis nutrients
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.
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.
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.
In the final week or so before harvest, be sure to give your plants only water to clear any nutrient buildup in the buds—this is called flushing.
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.
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.
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.
When using liquid nutrients for cannabis plants, it’s important to have a watering schedule to write down and track:
- How much water you use
- How many and what kind of nutrients you use
- How frequently you water
You don’t want to use liquid nutrients every time you water—use them every other watering, or two waterings on, one off. It depends on the complexity of your soil and the health of your plants. Too many nutrients will damage your plants.
Giving weed plants the proper amount of nutrients requires careful monitoring. Many growers start at a solution dose lower than recommended and work their way up until plants respond optimally. Too little nutrients and the plants will have stunted growth, while too many can lead to nutrient burn and lockout.
Check your pH
It’s important to get a pH meter to check the pH level of your water when mixing nutrients. Cannabis prefers a pH between 6 and 7 in soil, and between 5.5 and 6.5 in hydroponic media. Letting the pH get out of this range can lead to nutrient lockout, meaning your plants are unable to absorb the nutrients they need, so be sure to test your water regularly and make sure the nutrient mix you give plants falls within the desired range.
Comparing nutrient and fertilizer brands
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.
|General Hydroponics||Their Micro, Grow, and Bloom are gold standards in nutrients, and great for beginners and pros alike.|
|Botanicare||Another solid nutrient provider, their Grow and Bloom formulas keep things simple and plants happy.|
|Dyna-Gro||Their Pro-TeKt is great for adding to plants during flowering.|
Organic cannabis fertilizers
Organic fertilizers are nutrients that come from organic sources such as animal and vegetable waste. They also include sediments like glacial rock dust and gypsum that contain beneficial minerals for the soil and plant. They are common for outdoor growing and usually come in powder form.
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.
Most of these fertilizers can be purchased cheaply at your local nursery and then mixed into soil before potting outdoors. Done correctly, you’ll only need to water your plants throughout the growing process, as all nutrients are in the soil.
We recommend these organic fertilizers:
- Blood meal or fish meal for nitrogen
- Bone meal or bat guano for phosphorus
- Wood ash or kelp meal for potassium
- Dolomite lime for calcium and magnesium
- Epsom salts for magnesium and sulfur
Commercial soil blends also exist that already contain the proper mix of these nutrients.
Benefits of organic fertilizers for cannabis plants
One of the best things about organic fertilizers is they improve the soil while also improving the quality of your plants. Other benefits:
- The slow release of nutrients protects plants from too many nutrients
- Over time, organic fertilizers will improve the quality and diversity of life in soil
- Improved airflow and water retention in soil
- Renewable and sustainable
- Organics stay in the soil with a lower chance of nutrient run-off
Some growers also find that growing organically increases the flavor profile of finished cannabis as well as increases yields.
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.
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.
Disadvantages of organic nutrients for cannabis plants
There are some complications in working with organic fertilizers. The main issue is if your weed plants have a nutrient deficiency, it takes longer for a plant to absorb organic powder nutrients, which can increase the damage to plants. Liquid nutrients act much quicker. Other disadvantages:
- They take time to be absorbed by the plant
- Require microorganisms to break down nutrients, which may slow in colder temperatures
- Can introduce insects and pests
How to make compost tea for marijuana plants
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.
The goal of compost tea is to introduce nutrients, fungal colonies, and beneficial bacteria to either the soil or foliage of a marijuana plant to aid growth and protect it from harmful disease, promoting bigger, stronger, and more resilient plants.
Compost tea should never be a 100% replacement for nutrients, but it can be a great complement to other nutrients.
You can add compost tea to weed plants by:
- Spraying it on leaves
- Applying it to soil
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.
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 tea recipe for marijuana plants
A healthy compost tea pulls soluble nutrients and microorganisms from compost, including bacteria, fungi, and protozoa.
Here are five key compost tea ingredients recommended by the Beneficial Living Center located in Arcata, California, to create a successful tea that will work best for your cannabis.
- Compost: A healthy compost should have large populations of microorganisms and nutrients, and sourcing it locally will ensure organisms are local pathogens. Compost that contains developed mycelium (fungal colonies) populations will help aid the development of fungal growth in the tea.
- Worm Castings: These byproducts expelled from a worm after digestion provide a high density of nutrients in a broken-down, refined form readily available for plants. Worm castings also introduce microorganisms.
- Fish Hydrolysate: This is produced by breaking down fish and crustaceans to create a nitrogen-dense product. Crustacean exoskeletons also have chitin, which works as an immune booster for plants. Fish hydrolysate also helps feed and increase fungi populations.
- Kelp: This serves as a source of food for fungi that grow while the tea is brewing. It’s also thought to provide a surface for fungal colonies to attach to and develop.
- Molasses: Serves as a source of food for bacteria that grow while the tea is brewing.
How to make compost tea in 5 steps
Build a compost tea brewer
Before building a compost tea brewer, you need to consider the size of your cannabis garden. Most homegrows use 5-gallon buckets. On the outside of the bucket, you’ll need to have an air pump connected to an aerator device at the bottom. The aerator and air pump will oxygenate water so microorganisms can breathe.
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.
Build your schedule
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.
Only start a tea when you can apply it within 36 hours of brewing it. When using as a spray, apply in the evening or morning when the temperature is low and without direct sunlight. This period is also when the stomata—pores in the plant’s foliage—are open to receive nutrients.
Fill your compost tea bag
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.
Finalize your compost tea
There are multiple products that can be added in the middle of your brewing process, toward the end, or right before application: Food for bacteria and fungi can be added halfway through the brewing process to increase the growth of microorganisms; products like SeaGreen and Actinovate can be added before the tea is applied to plants for additional benefits.
Applying compost tea on cannabis
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.
Don’t put compost tea through drip irrigation lines because it will clog them up over time. It’s important to either gravity feed the tea or use a diaphragm pump—as opposed to a centrifugal pump—to avoid chopping up and disrupting the active microorganisms when watering.
Trevor Hennings contributed to this article.
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