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Best Soil for Indoor Cannabis Cultivation

Whether you call it a growth medium or dirt, the soil is one of the most important components in a successful cannabis cultivation effort. Choosing the right soil for your plants is one of the most important decisions to make when growing weed, and that choice may make the difference between a bountiful harvest and a meager one.

The perceived simplicity of soil selection often fools cannabis newcomers, and many make mistakes that damage their harvest. As a cultivator, you will have to make numerous considerations. For instance, the soil used for an indoor grow op will be drastically different from the growth medium used to grow weed outdoors. Then, there are matters of soil drainage, pH, and more.

When selecting soil for indoor cannabis cultivation, there are numerous brands and types available. With so many options, how do growers choose the right growth medium? Regardless of if you live in Vermont or Rhode Island, you will need to take these things into consideration when deciding on the best soil for your crop.

Making the Choice Between Soil and Hydroponics

If you are growing cannabis at home, you will have two choices: hydroponics or soil. Hydroponic systems are extremely effective and can provide great yields, but they are often prohibitively expensive for inexperienced cultivators.

As a rule, first-time growers should choose soil for simplicity’s sake. The plants’ roots will grow deep into the soil as they seek water and vital nutrients.

No matter the growing system you choose, the temperature should stay at or near 68° F and the growth medium should remain mostly moist.

It’s much easier to irrigate and fertilize soil than it is to do so with a hydroponic system. With the information acquired from thousands of years of successful cultivation, even an inexperienced grower can become an expert.


Container Size and Its Effects on Crop Yield

When growing cannabis, container size determines the complexity and size of the plants’ root system. Problems typically arise when the roots get too big for the container, so it is important to choose carefully. While the plants are in the seedling stage, 10x10x10cm containers are acceptable.

Once the plants grow to about 25cm in height, they can be transplanted to containers approximately twice that size. When they have reached 80cm, move them to containers with a 12-liter capacity or larger. As the plants grow, so do their space requirements.

Watering the Soil

The growing environment and soil type determine the amount of water required. Grow ops in hot areas like Arizona and Georgia need a bit more water, while growing in cooler areas, like Minnesota, requires less. During watering, essential minerals and nutrients move into the roots and toward the rest of the plant. Water is a crucial component in photosynthesis, and it works to cool overheated plants. Generally, it is best to water the growing medium until it is moist but not saturated. Overwatering encourages fungal growth, which may lead to root rot and other problems.


The Right Soil for Marijuana Plants

Growing soil comes in four different varieties: clay, loam, sandy, and silt. Though many growers believe there is only one kind of soil, that is simply not the case. Many commercially available soils are a combination of two or more types, and if that is not confusing enough, there are different soil ratios to consider. Each type has its benefits and drawbacks, and some of these are discussed in the sections below.

  • Sandy soils are known for their low pH and large grains. The biggest problem with sandy soil is that it dries rather quickly and sometimes fails to absorb moisture. Nutrients are often washed away, leading to rapid nitrogen depletion. However, sandy soils are easy to use for cultivation and offer great drainage. Sandy soil is a great option for indoor growers.
  • Silty soils consist of fine-ground organic particles and minerals like quartz. Though they hold moisture well, silty soils also provide adequate drainage and are easy to handle when wet. Silt-based soils are very fertile, which improves the chances of a successful harvest. With frequent watering, it is possible to lengthen the growing season. Silty soils are one of the best choices for seedling growth.
  • Loamy soils are a combo of clay, silt, and sand, usually in a 40/40/20 ratio. These soils have at least 20% organic content and may be easy or difficult to use. Loamy soils form loose balls that are easily broken apart. This soil has a nearly neutral pH and is popular among cannabis cultivators for its excellent water retention, drainage, and fertility. However, loam growth mediums can be expensive.

Clay soils are a great organic option for marijuana growers. These soils are composed of crystalline particles derived from chemical reactions. It is easy to shape or mold clay soil, but it drains poorly and is tough to work with. Those using clay soils may find it hard to get the plants’ roots to grow downward. Clay soils have a higher pH that stabilizes plants, but usage requires additional effort.

Why is Loamy Soil So Popular Among Cannabis Cultivators?

Without a doubt, loam is the preferred soil-based grow medium among weed growers. It is great for other potted plants, so why wouldn’t it work for cannabis? Loamy soils contain the ideal balance of sand, silt, and clay, as well as humus. This combo ensures high pH and elevated calcium levels. out

Loam is dark in color and is crumbly, dry, and soft to the touch. Though it tightly holds onto water and plant nutrients, it drains very well and allows air to move freely between particles and down to the plants’ roots.

Making Loam Soil

As mentioned previously, loam is a combination of the other three soil types. However, it is not easy to replicate. For instance, if you try to mix clay and sand, you will end up with something like cement. Creating loam is not a quick or simple process, but this type of soil is best for cannabis plants.

It is worth the additional time and effort, and no matter which type of soil you are starting with, loam creation requires frequent supplementation with organic materials. Decomposing plant matter provides the superior drainage cannabis plants need. The only issue is that organic matter is rapidly depleted, which means you will have to adjust the mixture with each growing season.

The level of effort required to create loam depends on the nature of the existing soil. For example, if the growth medium is rich in sand or clay, you will need to add organic matter more often. Add a two-inch-thick layer onto the surface before working it down into the soil.

Buy the Right Kind of Soil for Your Marijuana Plants

A novice grower may visit their local home and garden store with little knowledge and a healthy dose of enthusiasm. However, that vigor may quickly fade when faced with an overwhelming number of options. First and most importantly, never buy soil in bulk. Even if you are growing hundreds of our wholesale seeds, you want top quality soil to grow them in. There are no standards or certifications for soil quality, and some less-ethical sellers provide growers with low-quality soil from worksites and other undesirable places.

When buying cannabis growth media, it is crucial to understand what makes soil good for cannabis plants. If you want plants with plenty of trichomes and cannabinoids, you will have to consider variables such as:

  • Texture
  • Drainage
  • Water retention

Texture, Drainage, and Water Retention

The soil’s water-holding capabilities, drainage, and texture are some of its most important components. It is impossible to get a great yield if the soil does not have the proper mixture of oxygen and water. If there’s excess moisture, the plants’ roots will not be able to absorb water or the oxygen it provides. If the soil is too dry, the roots may become dry and damaged, and the plant may become dehydrated.

To prevent plant hydration problems, top-quality soil for cannabis cultivation should have:

  • A dark, rich color
  • A loose texture
  • Good drainage. Water should not pool atop the soil for more than a second or two.
  • Adequate water retention without mud

It is very unlikely that the soil will come with the right water retention, texture, and drainage. Thankfully, there are several ways to improve the quality of your grow medium, such as:

Adding Coco Coir

This additive is made from the husks of coconuts and it improves water retention without adding weight to the soil. When coco coir is added, the plants’ roots will develop sooner and there’s less likelihood of overwatering. Many people grow cannabis in 100% coco coir, but 30% is the ideal level for soil.

Using Vermiculite and Perlite

With the addition of vermiculite, the soil will feel lighter, but it will retain more water. Vermiculite is often used with perlite for improved results. Perlite is commonly used, and it is well-suited to most soil mixes. It is composed of light, airy particles that are dusty white in color. Perlite somewhat resembles popcorn, and it oxygenates the soil while improving drainage. 10%-20% perlite is a great place to start, but some growers go up to 40% at the risk of nutrient runoff. When using vermiculite and perlite, the level should be kept at or below 50%.

Stirring in Some Worm Castings

It may sound gross, but worm poop makes for better-quality cannabis. These plants love the nutrients found in worm castings, and this additive improves drainage, water retentio0n, and soil texture. Natural nutrients break down quickly, and because these nutrients have already gone through the worms’ digestive systems, they are more easily absorbed. For best results, add about 30% worm castings to the soil.

Soil Nutrients

If it has been properly chosen, cannabis soil should already be rich in nutrients due to its high organic content. A common mistake is to attempt to use organic matter such as rotting vegetables and animal manure as fertilizer. This kind of content must first be broken down so the plants’ roots can absorb its nutrients.

Indoor Growing Requires Nutrient-Rich Soil

If you are growing weed indoors, for THC or CBD extractions, you will need to find soil with plentiful nutrients. Indoor grow ops do not receive nature’s benefits, so a little supplementation is in order. Though it is possible to sterilize the soil with heat and mix in some rich potting soil, it is much easier to buy it ready-made from a garden store. Be sure to provide plenty of water, keep the temperature stable, and occasionally test the soil’s pH level.

Soil pH and Why it Matters

If you did not already know, pH is an acronym for the ‘potential of hydrogen’. This chemical scale is a measure of a substance’s acidity or alkalinity, and it ranges from 0 to 14. A 7.0 pH is neutral (water is a common example of a neutral substance). Anything from 0 to 6.9 is acidic, while anything from 7.1 to 14 is considered alkaline.

Hydrochloric and battery acids have a 0 pH, while liquid drain cleaners have a pH of about 14. Ideally, cannabis soil should be slightly acidic, with an ideal pH of approximately 6.0. However, anything between 5.8 and 6.3 is safe. Crops may survive outside these points, but yields will be substantially smaller.

Should Photoperiod Seeds Be Treated Differently from Auto-flowering Seeds?

Many homemade cannabis soil mixes are not well-suited to autoflowering strains. In fact, many custom soils are ideal for just one strain. The perfect soil mix can only be created with years of cultivation experience and a great deal of patience because of the unique traits of each strain and its associated environmental needs.

Additionally, so-called super soils are so nutrient-rich that they are only good for experienced cultivators of photoperiod strains. By comparison, autoflowering strains do better in light, non-fertilized soils. A 50/50 blend of peat soil and coco coir, with a healthy dose of perlite mixed in, is best for young photoperiod and autoflowering plants. In any case, it is best to minimize fertilizer usage during any strain’s seedling stage.

Buying the Right Soil

If you are growing cannabis for the first time, a trip to the garden store is a great first step. In fact, most expert growers buy their soils from the same places! When talking with the store’s employees, it may help to ask about soils for growing tomatoes. 710 plants (another term for cannabis) and tomato plants thrive on many of the same nutrients, and it is a great option if you would rather not disclose your plans to grow marijuana.

In Closing

Growing marijuana in the soil is a natural, effective way to get the flavorful, fat buds everyone wants. Furthermore, the soil is much more forgiving than hydroponic growth media. With the tips and tricks in this guide, you will be well on the way to a successful crop. Start with seeds from weed-seeds.com!


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