by Nebula Haze
Got marijuana plants growing in soil? Many nutrients made for hydroponics work in soil. But do you know what’s way better? Using nutrients that were made specifically for growing cannabis in soil. Soil nutrients have cool, unique properties that you won’t want to miss! Here are my top cannabis nutrient picks:
- Fox Farms Nutrient Trio for Soil – professional-grade marijuana soil nutrients, popular, mostly organic.
- Botanicare Pure Blend for Soil (Grow and Bloom) – perfect for beginners, one bottle for each stage of life.
- Dyna-Gro Grow & Bloom – cheapest option, easy to use, but still produces great bud quality.
Weed plants in soil love extra nutrients!
Keep reading to become an expert at soil nutrients for growing marijuana…
Table of Contents
Do You Need Special Nutrients to Grow Marijuana in Soil?
What Type of Soil Should I Get?
Which Company Makes the Best Soil Nutrients?
Tips for Growing Marijuana in Soil
Do You Even Need Special Nutrients to Grow Marijuana in Soil?
- Cannabis has high nutrient needs, especially in the flowering/budding phase. Without enough nutrients during budding, the plant won’t make buds as big as they could be.
- You can avoid using extra nutrients altogether by growing in well-amended composted soil and transplanting your cannabis into a nice big pot with fresh composted soil right before the switch to the flowering stage, which should be enough to last through the flowering stage. In composted soil, tiny microorganisms slowly bread down the nutrients for your plants, so the nutrients are fed to the plant slowly and regularly.
- A potted cannabis plant in regular (non-composted) potting soil often uses up all the nutrients in the soil before they even make it to the flowering stage. After about 3-4 weeks of growing in an average sized pot, a cannabis grower either needs to repot the plant into new, fresh soil, or supplement with extra nutrients in order to get everything to the plant that it needs.
- There are “natural” ways to provide extra nutrients to your cannabis (for example egg shells, coffee beans, dolomite lime, etc all add minerals and nutrients) but these usually do not break down fast enough or consistently enough to make sure your cannabis doesn’t run into nutrient deficiencies. Another problem with using things like this is that giving your plant too much of one nutrient can actually make it deficient with another nutrient. So it can be difficult to get the right proportions right unless using a soil recipe that’s specialized for cannabis or by adding extra nutrients in the water.
- Want more info? Since it’s just a weed, why can’t I grow cannabis in the regular dirt outside?
Fox Farms Ocean Forest soil (pictured here) is a top soil for growing cannabis. It just works.
How to Get Enough Nutrients to Your Marijuana Plants
To make sure your cannabis plants don’t run into nutrient deficiencies while growing in soil, you need to either…
- Grow with composted soil OR
- Regularly transplant to new. fresh soil OR
- Grow in a really, really big pot with tons of soil OR
- Supplement with specialized marijuana nutrients formulated specifically for growing cannabis in soil (recommended)
Conclusion: Adding soil nutrients to the water tends to get the best cannabis yields, potency, and density.
Fox Farm Nutrient Trio – excellent, mostly organic marijuana nutrients.
What Soil Should I Get to Grow Weed?
Not sure which soil should you start with? I recommend starting with Fox Farms Ocean Forest soil. This is a potent cannabis soil mix that has enough nutrients to last even a hungry cannabis plant for several weeks. No need to think about nutrients for a little while.
Fox Farms Ocean Forest soil is a nutrient-rich marijuana soil that grows thriving weed plants.
My other favorite cannabis soil is Fox Farm Coco Loco, which contains a bunch of coco (ground up coconut husks) instead of peat moss. Coco Loco soil is lighter on nutrients yet also holds more water than a peat-based soil like Ocean Forest. So you can water cannabis plants in Coco Loco soil a little less often, but you should start to add nutrients in the water once plants are a week old to get the fastest growth. Once you start adding nutrients in Coco Loco, cannabis plants grow fast!
What size pot for soil?
A fabric pot (also called a “smart pot”) is a container made out of fabric. Fabric pots works perfectly when growing cannabis plants in soil since they help deliver more oxygen to the roots. Hard-sided pots can also be used, though plants might not grow quite as fast.
- 3-gallon fabric pot – For a smaller grow, 3-gallon pots might be better because they take up less room, and the reduced root room helps keep plants smaller.
- 5-gallon fabric pot – For an easy, low maintenance soil grow, use 5-gallon fabric pots. This won’t need to be watered as often, though they do take up more room.
Proven Soil Watering Schedule
- How often to water? Make sure to follow a proven soil watering schedule.
- Proven watering schedule – Use a proven cannabis seedling watering schedule for growing weed in soil.
Don’t want to use nutrients? Learn how to mix up your own super soil so it has all the nutrients your cannabis plants will need! Bonus: With composted super soil made using the recipe in the link above, you don’t need to worry about maintaining your pH! your super soil will automatically manage the pH for you.
What Are the Best Soil Nutrients?
- Use a “Vegetative” (high Nitrogen) nutrient formula for the vegetative stage after your plants have used up all the nutrients in the soil
- Use a “Bloom” (low Nitrogen) nutrient formula for the flowering stage
But are they the best marijuana nutrients? Which one is the best?
There are so many nutrient options out there! How can growers figure out which ones are actually the best cannabis nutrients? In fact, what makes a nutrient system good or bad for growing cannabis in the first place? The answer is it’s about the NPK nutrient ratios!
| Optimal Cannabis N-P-K Nutrient Ratios | |||
| Life Stage | N | P | K |
| Vegetative/Grow | High | Medium | Medium or High |
| Flowering/Bloom | Low | Medium or High | High |
* In a pinch, nutrients for cactus or succulents can be used in the flowering stage until you get better nutrients because they have similar nutrient ratios
These aren’t the only nutrient ratios that will work for growing cannabis, but these ones work well. Adding cannabis nutrients to your grow can help you get the best potency, yields and growth from your plants, especially in the flowering stage when cannabis uses a lot of nutrients to make bud. Cannabis plants have two stages of life and they need the right nutrients at the right time.
Note: Don’t use anything with time-released nutrients (like fertilizer spikes, or Miracle-Gro soil – they deliver too much N in the flowering stage).
Most nutrient bottles have 3 numbers, often called N-P-K, which stands for Nitrogen, Phosphorus and Potassium
(Why “K? The atomic symbol of Potassium is “K” from Neo-Latin kalium)
Marijuana plants need different ratios of these 3 nutrients (as well as several micronutrients) depending on what stage of life they are currently in.
For example, cannabis plants in the vegetative stage need nitrogen to power the growth of leaves. In the flowering/budding stage, cannabis needs less nitrogen and greater levels of phosphorus to assist with proper bud growth.
Because of the varied nutrient needs of the cannabis plant, it’s often easier for many growers to use a professional nutrient system made for a plant like cannabis, instead of trying to mix up their own. With a professional nutrient system, you don’t have to figure out your own changing nutrient ratios, and you don’t have to worry about chemical reactions that occur from combining different types of nutrients incorrectly (which can create fertilizer salts and cause nutrient lock-out).
A professional cannabis nutrient system will save many growers a lot of time, frustration and money. There are many nutrient systems to choose from which have been created by long-time cannabis growers and breeders around the world!
When it comes to finding a nutrient system to use with your cannabis plants, the first question you ask yourself should be: “What is my growing medium?”
Warning: When it comes to growing cannabis, avoid any nutrients which claim to be “extended” or “slow release”! They can cause all types of unexpected problems.
If you’re growing in soil, you will want to get nutrients made for soil.
With all nutrient systems, don’t start at full strength or it might burn your cannabis plants!
Different strains have different preferences, and some plants are very sensitive to nutrient burn.
How Much Soil Nutrients to Give Cannabis?
- Start at half strength – I recommend starting new nutrient systems at half-strength and only raise the nutrient levels as needed.
- Fast-growing plants need more nutrients – If your cannabis plants are growing very fast (inches a day) they likely need full-strength nutrients regardless of the type of grow light.
Other Factors That Affect Nutrient Levels
- Small grow lights require less nutrients for plants to be healthy, on average – Many home growers will never need to raise nutrient levels above half-strength because their plants are under relatively small LED grow lights (100-200W). Plants just aren’t “digesting” enough light to need lots of nutrients.
- Big grow lights often require need full-strength nutrients – On the other hand, cannabis plants are under powerful, bright lights may require full-strength nutrients (or even more in rare cases).
- Individual plants have different needs – Some strains or specific cannabis require more or less nutrients. You sometimes notice you have plants in the same environment, but some plants get “hungry” for nutrients while other plants getting the same conditions are getting enough or even too much.
- Pay attention to plants more than anything! If a plant looks like it needs more nutrients, give it more. If it looks like it needs less, give it less.
Plants turn yellow or lime green all over when they need more nutrients overall.
If leaves are dark green all over, they probably need less nutrients overall.
“Nutrient burn” (dry, brown, possibly curling tips) is another sign of too-high levels of nutrients or supplements. Pay extra close attention if nutrient burn affects all the leaves at once, especially if you see it happen right after raising nutrient levels or adding a new supplement.
Nutrient burn on all the leaves is another signal the nutrient levels are too high.
Plants use light for food (and to power the growth of buds), not nutrients. Just like eating a bunch of multi-vitamins every day will make you sick, giving plants too high levels of nutrients can make them sick, too. With plants, just like humans, you will get the best results by paying attention to nutrient needs on a regular basis. Don’t wait until your whole plant is yellowing to try to figure out the problem!
Some growers try to push their plants to the limit of what they can take, giving stronger and stronger levels of nutrients until plants show signs of nutrient burn, but I don’t believe this is necessary. Sometimes less is more. I believe that as long as your plant is not showing signs of deficiencies (such as growing pale green leaves towards the bottom of the plant), you are generally in the right range.
Many cannabis growers will find that professional nutrients work well at half-strength, and only growers with very bright lights and fast-growing plants will need to raise nutrient levels above that. There are also certain strains that seem to do better at higher nutrient levels than most others.
Here are pictures of cannabis plants with nutrient problems (and solutions).
Please, save yourself the time and frustration – get a nutrient system that’s proven to work for growing cannabis! If cost is a worry…
An Example of Cheap (But Effective) Cannabis Nutrients: Dyna-Gro Grow & Bloom. Use Dyna-Gro “Grow” bottle in the vegetative stage & Dyna-Gro Bloom bottle in the flowering stage. This cannabis nutrients work great for growing marijuana. You don’t need anything else besides these two bottles of nutrients to grow weed all the way to harvest and this simple cannabis nutrient system is cheap (effective for soil, coco coir and hydro!). If you’re not sure which nutrients to get and you’re on a budget, consider going with Dyna-Gro!
An easy and simple nutrient systems that for beginning cannabis growers in soil is the Fox Farms Nutrient Trio for Soil. These are professional-level nutrients, and one of the the most popular nutrient systems for growing weed in soil.
Fox Farm Nutrient Trio – excellent, mostly organic cannabis nutrients.
The Fox Farms trio works great for growing any cannabis strain, without needing any additional supplements.
There are three different bottles that you will need to grow cannabis, “Grow Big,” “Big Bloom,” and “Tiger Bloom.” They are often sold together. Simply follow the included nutrient schedule (here’s a PDF, here’s a JPG) from Fox Farms.
Make sure you get the soil version if growing in soil, because Fox Farms offers a hydroponic version of the same nutrient line.
IMPORTANT: Root pH Affects How Well Your Cannabis Absorbs Nutrients!
Nutrient Picks for Growing Cannabis in Soil
- Fox Farms Nutrient Trio for Soil <– Very concentrated, less is more. “Grow Big” & “Tiger Bloom” provide most of the major nutrients your cannabis needs, while “Big Bloom” has many micro nutrients 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. They offer a lot of supplements, but the only bottles you need to be successful growing cannabis is the FF trio, which is highlighted in green on the schedule. The trio tends to be strong, so use it sparingly (especially “Grow Big” & “Tiger Bloom”). I recommend giving plain pH’ed water every other watering to make sure your plants only get exactly what they need.
These cannabis plants were grown in soil with Fox Farms Nutrient Trio for Soil nutrients
- Botanicare Pure Blend for Soil (Grow and Bloom) – Vegetative Stage (“Grow” formula) & Flowering Stage (“Bloom” formula) nutrients <– Recommended for Beginners because this nutrient system is easy to use, relatively cheap, and can be found at almost any hydro store or online. Botanicare Pure Blend for Soil works great for growing any cannabis strain, without needing a lot of extra care, or any additional supplements. The two bottles are all that’s needed to get your plants successfully to harvest time. You can follow the instructions on the bottle or use the feeding schedule from Botanicare (here’s a PDF, here’s a JPG). They offer a lot of supplements, but the only bottles you need to be successful growing cannabis is the Pure Blend 2-pack, which is what’s reflected in the “standard” version of their schedule. Repeat “Week 3” of the Vegetative part of their schedule until the end of the vegetative stage if it lasts longer than 3 weeks. For auto-flowering strains – skip week 3 of “Vegetative” & skip week 6-7 of “Flowering/Fruiting” – otherwise you can follow the instructions almost exactly.
- Dyna-Gro Grow & Bloom (sometimes called “Superthrive”) <– Cheapest nutrients that still work great for growing cannabis in soil. Use “Foliage-Pro” during the vegetative stage, and “Bloom” during the flowering stage. Just follow the instructions on the bottles!
Dyna-Gro nutrients are cheap but surprising effective at growing good weed.
These cannabis plants were grown with Dyna-Gro Grow & Bloom at 1 tsp/gallon (nothing else!).
Example of Dyna-Gro Plants: Strains are Pacific Punch (limited edition strain related to Purple Punch), Amnesia Lemon, and Zweet Inzanity. I grew these plants under a Mars Hydro TSL2000 LED grow light.
Zweet Inzanity close-up shot! Grown with only Dyna-Gro nutrients.
Don’t want to use nutrients? Learn how to mix up your own super soil so it has all the nutrients your plants need! Bonus: With composted super soil, you don’t need to worry about maintaining your pH! Instead, you are actually creating a specially made microbial soil mix that will automatically take care of the pH for your plants, while slowly feeding them the exact nutrients they need.
Tips for Growing Cannabis in Soil
- Low Levels of Nutrients Given Regularly is Much Better Than Giving a Lot of Nutrients at Once!
The most common mistake made by beginners growing cannabis in soil is they water their plants too often. Overwatering is almost never a case of giving your plants too much water at once. Instead, overwatering cannabis in soil is almost always caused by giving the plant water too often.
Learn how to water seedlings in soil (day-by-day watering schedule).
Never overwater your seedlings again, just use this seedling watering schedule.
How to water adult cannabis plants in soil
Wait until the top of your soil feels dry up to your first knuckle (about an inch deep)
Add nutrients to your water (if needed), then adjust the pH. Most soil growers only add nutrients every other watering, or even less often, but you will always need to adjust the pH of your water.
Start watering your plants and continue to add water until you see at least 20% extra runoff water drain out the bottom of your pot. Go back to step 1.
Use the above directions to water older plants in soil, like these 30-day old plants
Learn more about growing cannabis in soil!
