How to Grow Cannabis in Soil
First-time growers often start by growing cannabis in soil. If you’ve grown other plants in soil and/or have maintained a soil garden, this may be the best choice for you because you will already be familiar with a lot of what you need to understand to grow cannabis in soil.
Avoid Miracle-Gro! Do not use “Miracle-Gro” soil or any soil that has “extended-release” nutrients for growing cannabis. These types of soil will continue to release nitrogen to your plant roots for up to 6 months. This can cause deficiencies or burn your cannabis plants in the flowering/budding stage, reducing your overall yields. I have seen growers successively grow cannabis in Miracle-Gro, but many of them struggled with nutrient problems in the flowering stage.
Soil Pros for Growing Cannabis
Many Already Have Soil Experience – Growing cannabis in soil is similar to growing plants like tomatoes or corn – soil growing may be the most intuitive option for you, especially if you already have gardening experience.
Simple – hand-water your plants in containers
Outdoor Growing – most outdoor growers choose to grow with soil. In the wild, cannabis grows in soil, so growing outdoors in soil is most like a cannabis plant’s natural environment. Many people find that when growing cannabis outdoors, soil is the simplest and most intuitive way to grow. Growing with composted “super soil” gives the grower the ability to grow outside without needing to add synthetic bottled nutrients or manage the pH of the soil.
Option 1: Store-Bought Soil + Nutrients – Growers can buy soil online or at a store, and simply add nutrients throughout their grow while watering for thriving, happy cannabis plants.
Option 2: Compost or Purchase “Super Soil” – For those who don’t want to worry about soil pH or adding nutrients throughout the grow, there is the option of amending and composting your own super soil (or buying it already composted) specifically made for cannabis plants. While this option takes more time before you start growing, it can be somewhat simpler especially for those who have composted soil in the past.
Note: Some growers believe growing in organic composted super soil with a rich microbial life can actually improve the taste and smell of cannabis by causing a plant to produce higher levels of terpenes and terpenoids.
Soil Cons for Growing Cannabis
Pests – Soil is an organic material, and there are many types of bugs that can live in soil. Often, soil-growers seem to suffer more often from pests attacking their plants than hydroponic growers.
Slower Growth – Growing in soil is not as fast as growing in a soilless or hydroponic setup – hydroponic plants tend to get better growth rates, especially in the vegetative stage.
Get Soil and a Container for Your Cannabis Plants
- Common cannabis soil mixes include Fox Farms Happy Frog and Fox Farms Ocean Forest. Any high-quality organic soil mix will do in a pinch.
- Avoid Miracle-Gro soil or anything with “extended-release” nutrients!
- To improve drainage, it can be beneficial to add 30% perlite to aerate and loosen soil.
- Common cannabis containers include classic plastic pots, terracotta pots, smart pots (fabric pots) and air-pots. Learn more about different types of containers
Soil growing probably requires the least effort of any growing method (especially if growing in super soil). Your main effort will be spent watering your plants.
Not sure which soil should you start with? I recommend starting with Fox Farms Happy Frog soil and mixing the soil with about 30-40% perlite for a perfect cannabis soil starting mix. For the easiest soil growing, get a smart pot (a growing container made out of fabric – they work perfectly for growing cannabis).
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.
Maintenance Cost – After setup, the main maintenance will be replacing your soil every grow (highly recommended – reused soil often does not get great results even with added nutrients). Occasionally you will have to replace used containers that crack or break. You also need to think about the cost of electricity and replacing nutrients every few grows.
Maintenance Effort – Watering your plants, providing nutrients and managing the pH to prevent deficiencies (composted super soil has microorganisms in it to help manage pH and make nutrients available to your plant roots).
How long until harvest? Soil has relatively slower growth rates than hydroponic methods, but a tuned-in soil grow can achieve impressive growth rates if given a great environment and plenty of bright light. Most soil grows require 1-3 months of vegetative time (depending on how big you want your plants) plus 2-3 months of flowering/budding (depending on your strain).
Many growers feel that cannabis grown in organic super soil has the best smell/taste profile, though this is highly disputed among hydroponic growers 🙂
How long can grower be away? It’s important for a grower to always remain close by for their first grow, especially for inexperienced growers. Experienced growers can safely spend more time away from the garden.
Bigger containers hold more water and therefore give growers more time away, since constant watering isn’t needed. In the best-case scenario, it is always best to check on your plants at least once a day. You never know when a pest infestation will take hold, a plant will fall over, or some other unexpected event will happen.
Most Common Soil Mistake: Overwatering
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.
How to water 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. The most common reason growers get nutrient deficiencies is because they don’t adjust the pH of their water. Most soil growers only add nutrients every other watering (or even less often), but even when giving just plain water you still need to adjust the pH of your water to prevent deficiencies.
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.
Cannabis-Friendly Soil Nutrient Suggestions
For new nutrients you haven’t grown with before, always start at half-strength and raise the amount slowly. Do not use nutrients with every watering! Most growers will add nutrients every other watering or even less frequently. Remember, a little bit goes a long way. You can always add more nutrients later, but it’s a lot more difficult to take them back from the soil.
An easy and simple nutrient system for beginning cannabis soil growers is the Fox Farms Nutrient Trio for Soil.
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.
Be aware there is a soil version because Fox Farms offers a hydroponic version of the same nutrient line. Though in my experience the hydroponic version also works just as well in soil 🙂
Nutrient Picks for Growing in Soil
HydroOrganics Earth Juice Nutrients (Grow, Bloom) with the following supplements: Earth Juice Catalyst, Meta-K, MicroBlast & Hygrozyme (use as needed for roots)
This nutrient schedule was used to grow the following buds under a 250W LED.
Don’t Use Miracle-Gro or Other “Slow Release” Soils!
Say “No” to Miracle-Gro soil for growing cannabis!
Many of us have seen Miracle-Gro used around our homes, so we know that it works for ‘regular houseplants’. Cannabis is just a tough weed, so Miracle-Gro nutrients should work great for it, too… right?
No. Not really. Well kinda.
Standard Miracle-Gro nutrients (their all-purpose plant food) will work “just okay” for the vegetative stage of your plant’s growth, but anything with Miracle-Gro in it is a terrible choice for the flowering stage due to its high levels of Nitrogen. Using standard Miracle-Gro nutrients in the flowering stage will cause your buds to grow smaller than they could have, and they may possibly have a chemical taste from nutrient buildup in the plant tissue.
However, the real problem is Miracle-Gro’s “time-released” soil (or any type of extended-release spikes or soils that aren’t organic) which slowly release Miracle-Gro nutrients over the course of several months. These types of soil continue providing Nitrogen slowly throughout your plant’s life. That means your plant won’t be able to use up all the Nitrogen in the vegetative stage as it would with regular soil, again giving you the problem of too much Nitrogen in the flowering stage.
Basically, avoid giving your plants a lot of Nitrogen in the flowering stage! Anything that does that is not a good idea 🙂
General overview of soil growing. Get the pros and cons!
What is Good Soil For Growing Cannabis?
When it comes to growing cannabis in soil, unless you’re using a brand that is known for making soil that is specifically cannabis-friendly, there are a few things that you need to consider before starting a grow.
What should you look for in good cannabis soil?
I think most growers agree a good cannabis soil should look dark and rich, with a loose texture that drains well and can hold water without getting muddy (you want wet soil, not dirt-batter!). But beyond that, what do you look for?
The following video shows the soil texture you want (this is Coco Loco, an excellent soil for growing cannabis)
Some growers choose an amended and composted “hot” soil that slowly releases nutrients over time. With this type of soil, you typically just add water or natural supplements like worm tea from seed to harvest. Other growers prefer a lighter potting mix so they have more control, and give nutrients in the water once the plant roots have used up the nutrients in the soil. But which brands can you trust?
Some popular soil examples that I’ve used with good results include:
- Almost any organic soil potting mix – If you can’t order special soil online, ask for the best soil at your local gardening store. You can use almost any organic soil potting mix to grow cannabis. I say “organic” because that cuts out a lot of potentially problematic ingredients like slow-release chemical nutrients (which often cause nutrient issues in the flowering stage by delivering too much Nitrogen). If asked what you’re using it for, say tomatoes. You should plan to start adding extra nutrients in the water by the time a plant is a few weeks old as the roots will quickly use up everything. Try to look for soil with a rich and dark but loose texture. It’s a good sign if you see little white pebbles mixed in (this is perlite, which makes soil drain better). If a soil looks like dirt or mud, it’s no good!
- Roots Organics Original – This was the first soil mix I ever used to grow cannabis and I had a great experience. I’ve moved on to Fox Farm products because they were available at my local hydroponics store, and now I’m hooked on Coco Loco. But Roots Organics Original soil has been around for a while because it works great. As with most soil mixes, you will need to supplement plants with additional nutrients after a few weeks.
- Fox Farm Happy Frog soil– This soil mix is relatively light on nutrients so it’s great for seedlings. It’s also suitable if you plan to give nutrients in the water from seed to harvest. If you don’t add extra nutrients, your plants will use everything in the soil up quickly.
- Fox Farm Coco Loco soil– A coco-based soil mix with enough nutrients to last your plants for a few weeks. With Coco Loco, you should start supplementing with extra nutrients once plants are 2-3 weeks old. I personally like Coco Loco the best of any soil mix I’ve used. You can use it by itself and it’s also my favorite base potting mix for a “just add water” super soil grow. I feel like plants tend to grow happy and healthy while being more resistant to over or under-watering compared to the other soil mixes I’ve tried. It’s great soil for other types of crops too.
- Fox Farm Ocean Forest soil– A “hot” soil mix with lots of nutrients packed inside. You can start seedlings directly in this mix though they may show signs of nutrient burn at first until they get adjusted. Ocean Forest has enough nutrients to last your plants quite a while, though you likely should still give extra flowering nutrients once your plants start making buds in order to get the best yields, density, and bud quality. Cannabis plants need a surprisingly lot of nutrients in the flowering stage and you don’t want to starve the plants right as buds are forming.
Recommended soil nutrients:
- Fox Farm Soil trio – These 3 bottles include everything your plants need from seed to harvest. The FF trio produces superb weed with any high-quality soil.
- Learn about other cannabis-friendly nutrients
Important Cannabis Soil Considerations
- Drainage Ability
- Water Retention
Although that list looks vague and complicated at the same time, the requirements you want to meet are actually pretty simple; let me break it down!
Texture, Drainage & Water Retention
It’s easy to get caught up thinking about what nutrients and amendments are in the soil, and those are important, but perhaps the most important aspect of any soil is actually its texture, ability to drain, and overall water “holding” ability.
In order for a cannabis plant to grow and thrive, it needs a good mix of both water and oxygen at the roots at all times! Too much water and the plant roots can’t get enough oxygen (lack of oxygen at the roots is why plants get droopy from overwatering) but on the flip side if there’s not enough water retention the roots can be injured from drying out too quickly!
What gets the best results for growing cannabis is a soil with a light texture that is good at retaining water…but not too much!
Note: Don’t worry, there’ll be examples of good and bad soil in just a bit!
Signs of Good Cannabis Soil
- Appears dark and rich
- Loose texture
- Drains well (doesn’t make a pool on top of your soil for more than a couple of seconds and doesn’t take forever to drain out the bottom)
- Holds water without getting muddy (you want wet soil, not dirt-batter)
Example of “Good” Cannabis Soil Ingredients
- Composted forest humus
- Sandy loam
- Sphagnum peat moss
- Coco coir (sometimes labeled coco fiber)
- Earthworm castings
- Bat guano
- Fish meal
- Crab meal
- Bone meal
- Blood meal
- Dolomite lime
Note: You’ll likely never see any soil mix with ALL those ingredients, but I wanted to share examples of common cannabis-friendly ingredients and amendments that often appear on the label of good soil 🙂
If you get the soil part right, you have almost everything you need to get to harvest! With the correct texture, drainage and water retention, you’ve got a perfect base. Add good soil cannabis nutrients, especially in the budding phase, and you should get to harvest with great results!
Example of happy marijuana plants in good soil!
More About Common Amendments to Alter Texture, Drainage & Water Retention of Soil
- Perlite is one of the most common soil amendments. It is highly recommended for any soil mix that doesn’t have some already.
- Very light, airy white “rocks” that feel almost like popcorn and add oxygen while increasing overall drainage ability.
- Add perlite to the mix (10-40% of the total volume). Use less perlite if you want better water retention and don’t plan on using a lot of extra nutrients. This is because a lot of extra perlite can cause the nutrients leach out faster from the soil. Add higher levels of perlite if you want to use a lot of added nutrients or supplements without burning your plants (since perlite helps prevent nutrient buildup).
- Vermiculite “lightens up” heavy soil and improves water retention.
- Some growers use perlite and vermiculite interchangeably, though they’re not exactly the same. Vermiculite holds water much better than perlite, but is not as effective at adding aeration and drainage.
- Some growers use a little bit of both. If you go high with vermiculite, you don’t want to go as high with perlite and vice versa. Together, perlite and vermiculite should never make up more than 50% of your soil!
- Coco coir is made from coconut husks. It can be purchased as loose coco coir, in an amended potting mix, or as coco bricks which needs to be rehydrated before use (learn how to re-hydrate coco bricks). Sometimes you’ll find a “soil” mix that is pretty much all coco plus amendments, and these can be a great choice for cannabis. Coco has some unique properties that make it a good supplement for cannabis soil mixtures.
- Coco improves water retention, but doesn’t make soil heavy.
- Roots tend to develop faster and plants are less likely to suffer from overwatering in coco coir.
- Some growers grow in pure coco, but if you’re adding it to a soil mix as an amendment, you might add 10-30% coco coir.
- Worm castings is a nice way of saying worm poop, and cannabis plants love it!
- Improves texture, drainage and moisture retention
- Add a natural source of nutrients that breaks down slowly
- Usually contains high levels of beneficial micro-organisms due to going through a worm’s digestive system 🙂
- Add up to 30% worm castings in your soil (although it contains nutrients, it’s gentle enough that it’s unlikely to burn your plants even if you add too much)
Now here are a few examples of good and bad cannabis soil so you can see the texture you’re looking for!
Good Cannabis Soil
Rich and light composted soil. Since this soil doesn’t have a lot of perlite, it’s a good choice for a grower who doesn’t want to add a lot of extra nutrients or supplements in the water.
Good Cannabis Soil
Another light, rich soil mix with great drainage. Although there is a wood chip in this picture, for the most part the mix is completely composted and broken down. It’s normal to see some wood pieces in composted soil, but you don’t want to have to wait for a lot of wood to break down while your plants are growing – you want all that rich nutrient goodness to be readily available to your plant roots 🙂
Good Cannabis Soil
This soil has quite a bit of perlite, which is a good choice if you plan to feed heavily with nutrients and supplements since the extra perlite prevents nutrient buildup in the soil
Good Cannabis Soil
The plant is growing in organic, composted “super soil” which has enough amendments to last your entire grow, so the only thing you do is add water!
Here’s organic “super” soil up close
Bad Cannabis Soil
This soil is muddy, clumpy and waterlogged. It retains too much moisture, which makes it really easy to overwater your plants.
Bad Cannabis Soil
Cannabis soil should not have a whole lot of big visible wood chips in it. That means the soil hasn’t been fully composted, and all the nutrients and goodness in that wood is mostly unavailable to your plants.
Bad Cannabis Soil
Although this seedling is over a month old, it has stayed tiny. Its growth is stunted by the thick heavy soil that holds way too much water and not enough air. Note how some of the soil looks like one solid object.
Bad Cannabis Soil
Don’t use dirt from outside! It almost never works, especially if it looks like this!
Suggested Brands for Cannabis Soil
Fox Farm Ocean Forest Soil
Fox Farm has been around for over 30 years and makes some of the most common types of “cannabis soil” (at least in the US). They have several great soil mixes, including “Happy Frog” which is a great choice for seedlings and clones.
Their Ocean Forest soil mix is “hotter” soil (higher levels of nutrients) that contains ingredients that cannabis plants love, including earthworm castings, bat guano, fish meal and crab meal. The nutrients contained in the soil will provide everything your plant needs for several weeks. Although it might give young seedlings just a touch of nutrient burn at first, they can be started in Ocean Forest soil and will soon be able to use the nutrients and start growing quickly. Some growers might put a little big of Happy Frog on top of a container of Ocean Forest, just to make it a little more gentle for seedlings the first week or two.
If you are willing to keep transplanting to bigger pots as your plant uses up the nutrients in the soil, you don’t need to supplement with extra nutrients. However, even if you grow in the same pot from seed to harvest, Fox Farm offers a complete nutrient system that is also formulated for plants like cannabis and goes perfectly with their soil to make sure your plant is getting the right levels of nutrients throughout its life.
This plant is growing in Fox Farm Ocean Forest Soil
Kind “Super” Soil (Living Soil)
When cannabis growers talk about “super” soil, they’re usually referring to soil that has been amended with slow-releasing organic nutrient sources, and then composted for several months (learn more about super soil).
The composting process creates a “living” soil that is full of microorganisms in the rhizosphere (area around the roots). Properly composted soil has nutrient sources that slowly break down over the course of your plant’s lifecycle. It very closely mimics what happens in nature.
Super Soil has a colony of micro-organisms living in the soil which form a symbiotic relationship with your plant roots. They deliver nutrients to your plant, and in return they eat the sugars that get secreted by your roots!
The “micro-herd” in the soil delivers nutrients directly to your plants. As long as you’re using decent water, you usually don’t need to worry about pH or other things that can disrupt nutrient absorption in regular soil.
However, when growing with Super Soil, it’s a good idea to avoid watering too much at a time, as extra runoff waterwill drain away some of the nutrinets. Try to give just enough water to saturate the soil with very little extra coming out the bottom. Since you won’t be adding more nutrients through the grow, you want to conserve what’s in the soil!
Nugbuckets is a famous organic soil grower! Check out his plants!
Organic Potting Mix
This is what kind of soil to get if you don’t have any “good” soil available, but want something that is known to work for growing cannabis.
Generally, anything labeled as an “organic potting mix” will work. This type of mix hasn’t been amended with chemical slow-release nutrients, which is one of the main things you want to avoid with soil for cannabis. I know it sounds like heresy, but even the Miracle-Gro version of “organic potting mix” will work okay, because unlike their original potting mix it doesn’t contain chemical nutrients (though it still has poor drainage and moisture retention – almost any other type of organic potting mix is better!).
Usually an organic potting mix does not have enough nutrients to last your plants for more than a few weeks, so it’s a good idea to always supplement with cannabis-friendly nutrients, especially in the flowering stage when your plant is making buds and needs lots of extra Phosphorus and Potassium.
Espona Organic Potting Mix is found in many stores in the US, and works for growing cannabis!
What to Watch Out For With Any Soil Mix At the Store
- Look At and Touch It If You Can! You already have an idea what soil should look and feel like, but here’s a test: If you form the soil into a ball, it should stick together loosely, but it should also easily fall apart again if you squeeze it.
- No “Time Release” Chemical Nutrients in the Soil – These types of soil slowly release nutrients over the course of months, which provides too much Nitrogen in the flowering stage and could possibly impair overall bud growth.
- Soil Should Appear Dark and Rich – Pale, crumbly or sandy soil usually doesn’t have a lot of nutrient content that the plant roots can get to.
- Soil Has Little White Rocks In It (Perlite), if you see white, almost fluffy rocks dispersed through the soil like popcorn, that is usually a good sign because it means this potting mix was intended to have good drainage.
- Soil Isn’t “Heavy” – Cannabis grows best in soil with a light airy texture and great drainage, which may seem almost fluffy when it’s dry.
- Example of “Good” Soil Ingredients – Composted forest humus, sandy loam, sphagnum peat moss, coco coir (sometimes labeled coco fiber), perlite, earthworm castings, bat guano, fish meal, crab meal, bone meal, blood meal, Azomite, pumice, kelp, dolomite lime, mycorrhizae and leonardite. That’s not everything, just examples of cannabis-friendly ingredients you see the most often 🙂
- Examples of “Bad” Soil Ingredients – You don’t want to see wood or bark on the label if it doesn’t say it’s been composted first. Also if you see just the word “fertilizer” in the ingredients that’s often code for slow-release chemical nutrients, which you don’t want!
Try to get soil that looks like this!
I hope this soil tutorial helps you find the right soil for your cannabis setup!
What is Good Soil For Growing Cannabis? When it comes to growing cannabis in soil, unless you’re using a brand that is known for making soil that is specifically cannabis-friendly, there are a