Score: 5/5


The BuildASoil Potting Soil Version 3.0 contains an excellent blend of ingredients that makes this one of the best potting soils for marijuana on the market.

The formula is based on the company’s Basic Living Organic Soil. However, it also includes plenty of extra additions that are geared toward promoting overall plant health and ensuring a high-quality yield, both in terms of quality and quantity.

It comes pre-mixed and ready to use straight away, which minimizes wastage and preparation time. It’s also long-lasting, which helps to keep costs down.

Priced at $25 for a bag of soil that’s one cubic foot in size, it’s slightly more expensive than some of the other soils sold by BuildASoil. However, the excellent formula shows that the company has covered all bases, plus it contains more beneficial ingredients than other BuildASoil products, so it seems reasonable overall. Plus, a lot of the ingredients are taken from BuildASoil’s collection, so they’re of good quality and provide the best of everything that the company has to offer.


Base and Composts

Half of the base of this soil is made up of sphagnum peat moss. This greatly improves water retention, as it can retain up to 20 times its weight and hydrate plants as necessary over time. Not only is this beneficial for the plant, but it also cuts down on maintenance time for the grower.

Additionally, sphagnum peat moss contains micronutrients that get passed to the plant, as well as elements such as sulfur that encourage the plant to produce and express their natural terpenes. These terpenes are responsible for the color, smell, and taste of a plant, so the peat moss will contribute to the flower’s overall flavor.

BuildASoil uses a mixture of its own composts in this soil to provide the optimum base for growing strong and healthy marijuana plants. The first type is Oly Mountain Fish Compost, which is packed with microbes and nutrients after aging for two to three years. The second is Colorado Pinto Bean Compost, which contains an excellent blend of minerals and has an ideal pH, which helps with acid regulation in the soil in general. This combination of composts and peat is extremely effective and not often found elsewhere.

Other Natural Ingredients

Another natural ingredient that is included in the formula is worm castings. Specifically, BuildASoil’s own brand, #1 BuildASoil Worm Castings, which is marketed as being fresh (the company apparently often finds living worms still inside the castings) and “the best bulk [BuildASoil] have ever had the pleasure of working with,” according to the website. Many growers find worm castings help with fertilization, protect plants from disease, increase the overall yield, and shorten the germination cycle—all without the use of any chemicals.

Additionally, the inclusion of biochar means that the soil will hold onto water and nutrients better, which can be utilized by the roots of the plant as and when needed. This is extremely important and contributes to the overall yield as it acts as a kind of “drip-feed” fertilizer. It also eliminates the need to use synthetic fertilizers on the plant, which can damage the yield.

Moreover, the biochar used in this product is charged—meaning it has been mixed with compost (and, therefore, beneficial organisms) and left for a period (usually around 10 days). This is known to enhance the biochar’s benefit, so it’s a very welcome addition to the Potting Soil Version 3.0.

Aeration and Drainage

BuildASoil has ensured that this soil mix contains a number of ingredients that improve the overall aeration and drainage. The first example of this is pumice, which is a coarse material that has been ground and mixed with the soil. It helps to provide adequately spaced pockets between soil particles, thereby contributing to drainage and aiding aeration. This helps avoid rot in both the soil and the roots, which is a common way of accidentally killing plants.

Many soils geared toward marijuana contain perlite, which is similar to pumice. BuildASoil, however, has gone one step further by using parboiled rice hulls instead. Not only do they provide a natural, sustainable alternative to perlite, but they also work just as well to aid aeration and drainage, if not better. The fact they’re parboiled is crucial, as this kills all weed seeds and rice seeds—two things you definitely don’t want ending up in your soil, as they can contaminate or kill the marijuana plant.

Mineral Additions

Despite BuildASoil’s great choice of peat moss and composts, which naturally contain a range of minerals and nutrients, the Potting Soil Version 3.0 formula also includes mineral additions.

Basalt provides micronutrients such as iron and calcium, as well as soluble silicon, which helps to strengthen plant cell walls and improves resistance to disease and pests.

BuildASoil’s own premium montmorillonite is used to enhance the overall soil profile through natural micronutrients, as well as aiding regulation by absorbing any toxins present in the soil.

Gypsum soluble pellets are also included in the mix, providing vital nutrients in addition to improving water penetration.

Lastly, CalPhos supplies phosphorus, a critical part of plant nutrition that aids energy transfer and synthesis, photosynthesis, and the breakdown of carbohydrates. All in all, this is a fantastic mix that is guaranteed to provide any marijuana plant with all the essential minerals and nutrients it needs to grow quickly and produce a high-quality yield.

Soil Amendments

As well as mineral additions, BuildASoil also includes a number of soil amendments in the Potting Soil Version 3.0. First is milled organic malted barley, which provides an injection of beneficial enzymes into the soil. Organic alfalfa meal is an all-natural fertilizer that helps to replenish, enrich, and rebuild worn-out soil – plus, it accelerates plant growth, so it’s a great addition. Karanja cake not only promotes plant growth but also helps resistance to disease and improves overall soil quality. Lastly, organic kelp meal is an excellent fertilizer and source of nutrients. This is a fantastic mix of soil amendments that guarantees any plant will have a great base from which to grow.

Quick Summary – Pros and Cons


  • Fantastic mixture of high-quality ingredients to promote growth.
  • Fantastic mixture of high-quality ingredients to help water retention, drainage, and aeration.
  • There is no need to use additional fertilizers or soil amendments.
  • Comes in a heavy-duty bag and is ready to use straight away.
  • Reasonable price.


  • Quite a thick, heavy soil, which may not suit everyone’s preferences.