If you plan on harvesting top-notch cannabis buds, using good soil is crucial! Many factors affect the quality of the soil and how it interacts with your plant.
This blog article will focus on the factors you should consider when choosing soil mixes. We will give you some beneficial but straightforward tips on making or finding good cannabis soil for growing marijuana indoors or outdoors.
Why Soil Is Important for Growing Cannabis Plants
The soil quality is crucial for the growth of your plants, as it provides living conditions and essential nutrients for the root system. If you keep your cannabis plants happy, you are more likely to produce large flowers with favourable properties.
The importance of good potting soil for our plants (cannabis) is like a well-deserved warm meal. When finding the best potting soil for your plant, show respect and care by providing it with a spacious room and a healthy diet.
Different Types of Soils
If you want to grow your cannabis, you should distinguish between natural soils and potting soil mixes. Cannabis, like any other plant, needs nutrients, which the growing medium should provide adequately. Natural soils generally fall into four categories:
- Loam
- Sandy
- Silt
- Clay
In the cannabis growing community, many soils combine at least two of these four types. There are also different ratios of each soil type.
While natural soil needs some help with nutrients, potting soil mixes are specifically designed to deliver needed nutrients to a plant’s roots. Here are the most common forms of natural soil for growing cannabis:
Loamy Soils
Loamy soil is a mixture of organic soil types and different clay, sand, and silt ratios. The combination brings out the best qualities of these different soil types and avoids their undesirable characteristics.
An optimal ratio for loamy soil is about 40% sand, 40% silt, and 20% clay. It has an approximately neutral pH, ideal for marijuana and hemp plants. Some people believe that a pH of 6.0 is excellent for growing cannabis.
Loam typically has a pH close to neutral. Loamy soils are usually at the top of the list of best options when cannabis growers are looking for the optimal soil. This is because loamy soil provides top-notch drainage and excellent water retention.
High-quality loamy soils should be rich in organic nutrients and have high oxygen levels. Although loamy soils can be expensive, they provide an optimal balance of water retention, drainage and nutrients. The right balance is critical for the plant’s healthy growth.
Loamy soil is the best option for growing cannabis plants and many other crops of different soil types. Loamy soils are suitable for both outdoor harvesting and container growing.
Loam is usually the most expensive soil to purchase. But if you plan to grow the best possible crops, it can pay off in the long run. Plus, you can enrich your loamy soil by adding organic material.
By using compost, it’s possible to fertilize your organic potting soil, which is an ongoing, non-automated and time-consuming task. However, diligence and persistence will pay off in the long run.
Sandy Soils
If you’re a cannabis grower looking for soil that is easy to work with, sandy soils are a good choice. Due to the larger granule size – that is, the larger pieces of sand – sandy soils have good drainage.
However, water retention is poor. So when you water your cannabis, the nutrients are quickly washed away. On the other hand, the larger particle size makes the soil porous and allows the root system to get plenty of oxygen. This coarse soil mix is not the best option for many cannabis growers, as water retention is relatively poor.
Sandy soils, however, have the advantage of optimal drainage. Like silty soils, which have a particle size between sand and clay, sandy soils are relatively easy to work and amend. They are best known for their low pH and large granule size.
The problem with sandy soils is that they dry out quickly. In addition, water can leach nutrients and essential elements, especially nitrogen. In short, the pros of sandy soils include:
- Easy to prepare for cultivation
- Offering good drainage
- Containing high oxygen levels
Using sandy soil is one of the best options for growing cannabis indoors.
Silty Soils
Silty soils have a medium granule size, leading to more desirable water retention and less favourable drainage than sand. Silty soil mixes will naturally contain abundant beneficial organic minerals and nutrients.
These potting soils are easy to work with and are a good option for growing cannabis. Compared to loam, a silt soil mix has good water retention, and its drainage can be considered average. Silty soil mixes are fertile, malleable, and easy to amend.
Silty soils are composed of minerals like fine organic particles and quartz. This type of soil is one of the best for seedlings; it can retain moisture sufficiently and is fertile, giving you a chance to grow a decent crop. You can extend the growing period by watering it frequently.
The best cannabis soil, whether for indoor or outdoor growing, should meet the essential needs of young cannabis plants. These needs include:
- Correct pH levels
- Balanced nutrients
- A vital combination of microbes and fungi
- Earthworm castings
- Humus
Clay Soils
Clay soil usually has a high pH and a small grain size. This type of soil mix is rich in nutrients and minerals and is one of the best organic options for cannabis. Unlike sandy soils, clay soils have excellent water retention but poor drainage.
Due to their nutrient richness, clay soils are good organic soils but have the disadvantage of being heavy and difficult to work with. Clay soil consists of fine crystalline particles formed by chemical reactions between minerals and other natural resources.
You can shape or sculpt clay soil to your liking, but it drains poorly and is difficult to work. Plant roots may have difficulty penetrating the surface if you choose to use this type of soil. Clay soils tend to have a higher pH; they are heavy and require more effort overall.
Constituents of Soil
The organic potting soil in which you should plant the seeds from the top layer of the soil. This layer is naturally a mixture of organic residues, sand, clay and tiny rock particles. If you are growing cannabis for the first time, you need to buy high-quality soil. It should provide adequate nutrients to the plants throughout the growing cycle.
When it comes to the culture medium, you have two options:
- Use of soil
- A hydroponic system
Setting up a hydroponic system for cannabis cultivation is brilliantly effective, but it is expensive and requires technical knowledge or experience. That’s why those growing their marijuana for the first time opt for soil.
Cannabis Soils: Important Factors to Consider
When choosing a good potting soil mix, remember that not all potting soils are intended for the same use. Some potting soils are designed for the addition of liquid nutrients.
Probably the essential properties of cannabis soil are:
- Water retention
- Drainage
- Texture
Your cannabis plant will not produce a high yield without enough water and oxygen. If there is too much water, the root system won’t get the oxygen it needs. If there is too little water, the roots would quickly dry out and become damaged. High-quality cannabis soil should contain:
- A rich and dark colour
- Loose texture
- Excellent drainage, i.e., no puddle, should remain on the ground for more than a few seconds
Also, good cannabis soil should hold water without becoming muddy. It’s a long shot that your marijuana soil will have the perfect drainage, texture, and water-holding capacity. However, there are several additives you can use to alter your soil mix’s drainage, texture, and water-holding capacity.
Growing Cannabis: Outdoors or Indoors
Growing cannabis plants outdoors has many advantages. For example, it is affordable, and there is no need to build a high tunnel or greenhouse structure. Also, there is no need for artificial light if you have your plant in the right place in your yard or garden. This way, your plants can benefit from the free and abundant energy of the sun.
If you want to grow your cannabis outdoors, you do not necessarily need to provide expensive soil for your plants; the soil already in your garden might be enough. However, if you want to achieve spectacular results, you’ll need excellent cannabis soil so that your plants can live a happy and healthy life.
Organic Earthworm Worm Casting
Worm droppings/poop can improve water retention, drainage, and texture. Your cannabis plants love worm droppings. They help the natural nutrients break down faster. It usually contains helpful microorganisms passing through the worms’ digestive system. Just remember to keep the percentage of worm droppings below 30%.
How to Choose the Best Potting Soil
Here are the major factors you need to consider when choosing the best soil for cannabis.
Inorganic vs. Organic Soil
When it comes to potting soil, there are two main options: organic or inorganic. Organic soil mixes contain nutrients that come from organic sources. Since these soils are more environmentally friendly, they are the better choice.
And you can opt for soils with organic ingredients that are considered user and environmentally friendly. On the other hand, the inorganic counterpart could be cheaper and contain chemicals.
The best organic soil is made with generous amounts of compost, peat and a controlled release of nutrients. Beneficial bacteria break down the nutrients in the potting soil. Specialized soils are sometimes said to contain enough nutrients for the entire plant growth and development cycle.
You can prepare a good cannabis potting soil mix by mixing several starting ingredients naturally. Many cannabis growers have reported good results with peat-based soils that do not contain wood products. The absence of wood reduces fungus gnats’ potential problems, thriving in an indoor grow room.
Cannabis growers can use a type of soil mix called “Lightmix.” This soil mix contains a mixture of ingredients plus perlite to aerate the soil better. The combination also includes a small number of nutrients for the first few weeks of plant development. Using Lightmix soil can be a good option for inexperienced growers.
Number of Cannabis Plants
Above, we mentioned typical soil mixes used for growing cannabis at home. However, some of these mixtures are not budget-friendly. So, before getting the best soil for cannabis, you should calculate the exact number of cannabis plants you want to grow.
An accurate estimate will save you from buying too little or too much potting soil. For example, if you want to grow 1 to 6 cannabis plants, it is unnecessary to buy a tremendous amount of soil that is superfluous. A single bag of soil should be enough to supply one to six weed plants in small containers or pots. You can also consider a bale or several bags of soil if you plan to grow several plants (more than six) in a large container.
pH Value
Like a battery or a jar of cucumbers, soils have a pH that significantly affects the properties of the soil. The pH is a quantitative means by which you can judge how acidic or alkaline a particular medium is.
This quantity can range from zero to 14, with zero completely acidic, 14 completely alkaline, and seven neutral. For cannabis soils, the optimal (required) pH is a near-neutral value that tends to be slightly acidic.
Quantitatively, this means your potting soil should have a pH in the 6-6.8 range. While cannabis plants can grow in slightly lower pH levels (more acidic), most commercial potting soils are offered between 6 and 7.
It is essential to keep an eye on the pH levels of your potting soil. If the pH deviates significantly from neutral, your plants will not absorb essential nutrients from the soil. When using liquid fertilizers to promote plant growth, monitor the pH levels of the soil.
Cannabis cultivators sometimes use phosphoric acid or lemon juice to regulate pH if the soil becomes too basic (having a pH above seven). Dolomite lime– containing high magnesium levels– is another excellent additive for controlling pH in the potting soil.
There are test kits you can use to measure the acidity of your soil. Alternatively, you can have a sample analyzed by a local lab. If the soil doesn’t have the right acidity, you can change the pH by adding soil amendments. You can also get suggestions from local nurseries or garden equipment stores.
Irrigation
The growing environment and soil type are important factors determining how to irrigate the potting soil. Depending on the temperature, you may need to regulate watering; hot climates require more water, colder climates less.
Watering your plant allows essential minerals and nutrients to reach near the roots, taken up and absorbed by the plant. Then, the needed nutrients travel to the other parts of the plant. Water is an essential requirement for photosynthesis and can cool down overheated plants.
Roughly speaking, it is recommended to water the soil to be moist to the touch but not wet. Be careful when watering because overwatering could encourage the growth of harmful fungi, which in turn can lead to root diseases!
Nutrients & Minerals
Besides light and water, plants also need nutrients and minerals. Therefore, when looking for the best potting soil, ensure it contains nutrients and minerals. Organic potting soil usually includes these nutrients, but they are depleted within 3-4 weeks.
This depletion occurs mainly when the cannabis plant starts to flower; during the flowering period, the plant needs more nutrients. Although there are plenty of other essential trace nutrients that are also required, the following elements are of utmost importance (the chemical symbol in parentheses):
- Nitrogen (N)
- Potassium (K)
- Phosphorus (P)
The microorganisms present in potting soil can convert organic material into functional nutrients. You can enrich your cannabis soil with additional ingredients, such as:
- Humus: soil leftover from plants, leaves, etc., after decomposition.
- Worm droppings: using the gobbled up dirt, mud or sand that a lugworm or earthworm throws up after passing through the worm’s body
- Bat guano: A fertilizer containing the accumulated excreta of bats
- Dolomite limestone (contains calcium and magnesium)
- Coconut fibre
- Mycorrhizal bacteria
- Nutrient-rich soil (compost)
You can also use liquid nutrients to help plant growth. However, you should use liquid fertilizers sparingly.
Coco Fiber
Coco fibre or coco coir is obtained from coconut husks and improves water retention without heavy soil. If you use coco coir, your cannabis plant’s roots should develop faster, and you are less likely to overwater it. You can grow the plant in pure coco coir, but a maximum fibre content of 30% should be enough.
Water Retention
The best soil for cannabis should hold water for an acceptable period. If the soil can not retain moisture, it will run off too quickly, causing the soil to dry out completely. While it is beneficial to use cannabis soil with good drainage, the water should not be completely flushed out so that the root system cannot absorb water and nutrients.
The term “water retention” refers to the ability of your potting soil to hold water. In other words, the appropriate soil for cannabis plants has good drainage properties while retaining moisture for the roots to absorb. If water retention is poor, your plant will also suffer from nutrient deficiencies.
Texture
Here, soil texture refers to the firmness /looseness of the soil. Clouds will form if the soil is too firm, preventing roots from developing and penetrating the soil. If the soil is too loose, it cannot hold enough water. Your soil should have the right texture to allow the root system to develop better. This development will help your cannabis plants grow faster.
Root systems provide nutrients and water to plants. Good soil texture ensures that enough air, minerals and nutrients are available for the root system.
Soil texture also balances water retention and drainage. Cannabis plants do best in light and crumbly soil; it provides plants with all the nutrients they need and promotes healthy root growth.
You can quickly test the firmness of your soil. Take a handful of your potting soil and squeeze it as hard as you can. After you open your hand, your ideal soil should fall back like loose dirt and not stick.
Additional Aeration
Your cannabis plant requires oxygen to grow. It is an essential element, and its concentration in the soil affects plant growth. Therefore, having a high amount of air pockets in your cannabis soil mix can provide numerous benefits to the plant. Some of these benefits include:
- Good drainage
- Improved water retention
- Better root development
Perlite
Some soil mixes contain perlite. It is an ingredient that speeds up the rooting of the cannabis plant. It can increase the amount of air in your potting soil. Poor drainage can lead to fungus and bacterial root rot in your original potting soil. You can check your soil mix to see whether it needs additional aeration or if you can get by without perlite.
Perlite is probably the most commonly purchased amendment suitable for virtually any soil mix. Perlite consists of airy ‘rocks’ known primarily for their white colour. Perlite resembles popcorn to some extent; it improves drainage and adds oxygen.
You can use between 10-20% perlite to enhance water retention in your soil. You can also use up to 40%, but you risk leaching nutrients faster. If you use perlite and vermiculite, do not use more than 50% for both together.
Vermiculite – which combines particularly well with perlite – can improve water retention and lighter soil.
Supplement-Based vs. Stand-Alone
Another fundamental aspect to consider before ordering potting soil is the nutrients already in the soil. In the case of standalone soil, choose a soil mix that already contains all the essential nutrients.
And in the case of supplement-based, choose a soft soil that you can amend with additional nutrients. The latter option is not ideal for seedlings. And if you want to buy this soft soil, you need to purchase additional nutrients.
As a rule, people tend to purchase soil mixes that contain some nutrients. In this way, you can change the total content of nutrients or minerals. However, you should have the experience to perform this method correctly.
Enriching cannabis soil can do more harm than good for beginners. Therefore, novices should consider standalone soil, an all-in-one potting soil.
FAQs About Growing Cannabis
Below, we answer FAQs about the best soil for cannabis;
Is Growing Cannabis in Soil Easy?
The vast majority of potting soil brands offer what they call “plug-and-play” soil for growing cannabis indoors. They claim that you don’t need to water the soil after planting your cannabis. In such cases, it is advisable to look for the best soil for cannabis that already has the desired pH.
Shall I Grow My Cannabis With or Without Microbes?
Reportedly, microbes help cannabis plants to be spared from diseases. In general, beneficial microorganisms – bacteria and mycorrhizal fungi – play a fundamental role in growing your marijuana roots and plants.
These tiny creatures (microbes) break down the nutrients you need so they can be more easily absorbed by your marijuana. An organic soil full of microbes brings various benefits, including:
- Promoting root growth
- Enhancing nutrient absorption
- Protecting the plant from harmful bacteria and fungi
Potting soils with microbes are probably more expensive than regular potting soils. Potting soil with beneficial microbes is ideal for indoor cannabis cultivation because it promotes healthy root growth.
Auto-Flowering or Photoperiod Plants?
If you want to find the best soil for cannabis, another essential factor is the type of cannabis you want to grow. If you’re going to grow auto-flowering plants, you should use organic potting soil that is relatively light and low in nutrients.
Let’s assume you want to grow auto-flowering plants. In this case, you should keep in mind that heavily fertilized soils or ready-made, standalone soils can (will) add too many nutrients to the seedlings, resulting in nutrient burn.
This condition occurs when you oversupply a plant with too much fertilizer or nutrients. Growing photoperiod plants may be more beneficial, starting with a seedling pot in cannabis soil specifically designed to be a starter soil with fewer nutrients.
Your prized seedlings can then be transplanted when it’s time (for example, amnesia haze seeds) into a more suitable marijuana soil for the next growth stage. You should remember that mature marijuana plants tolerate high amounts of nutrients better than seedlings in the later stages.
What’s the Best Potting Soil for Indoor Cannabis?
If you plan to grow marijuana indoors, you need the best soil for cannabis. A good cannabis soil mix for growing marijuana indoors should contain all the nutrients an outdoor plant needs.
As the cannabis matures, the plant’s roots (mainly) develop downward into the soil to find nutrients and water. Indoors, space for roots is minimal, resulting in smaller root systems than outdoors.
Since indoor marijuana plants don’t have as much room for root development, you should choose a soil mix that is spongy enough or not too compact. The temperature in the growing environment should be between 68 and 77 degrees Fahrenheit.
In addition, soil mixes that contain beneficial soil microbes are ideal for indoor marijuana to promote healthy root growth. It is advisable to look for ingredients such as worm droppings and bat guano that result in quality soil for indoor growing.
What’s the Best Potting Soil for Outdoor Cannabis?
One of the main advantages of growing marijuana outdoors versus indoors is the greater availability of soil nutrients and light. Mother Nature has already given you a soil mix with more than enough nutrients to grow high-quality cannabis if you live in a fertile place.
If you use fertile soil outdoors or buy your own, make sure the soil contains plenty of nitrogen, potassium and phosphorus. Soils with beneficial microbial life are ideal for growing marijuana.
Cannabis plants are usually less nitrogen-demanding when they flower. When buying your soil, look for slow-release fertilizers. This type of soil mix releases nutrients slowly.
Which Cannabis Seeds Should I Buy?
Now that you know what the best soil is for growing marijuana plants, you may consider purchasing cannabis seeds. For an excellent collection, check out our Cannabis Seeds. Make sure to plant them in nutrient-rich soil and keep in mind what we mentioned above.
Get in Touch
Since top cannabis soils deserve top seeds, we offer an excellent collection of high-quality seeds; contact us if you want to get started.
