Its water retention is good, yet it has adequate drainage. The minerals and organic substances within make it one of the most fertile soil types. • Medium-coarse • Pros: Contains minerals and nutrients, retains water well • Cons: Fair drainage. Loamy soil is a combination of sand, silt, and clay soils with added organic compounds. It is one of the best soil types for growing cannabis as it offers optimal water retention and drainage, and it’s rich in nutrients and oxygen.
• Mixture of sand, silt, and clay • Pros: Excellent water retention and drainage, contains nutrients, high oxygen levels • Cons: Expensive. This type of soil is heavy and not easy to work with. It is very rich in nutrients and minerals, which makes it a good option to include in organic grows. Clay soil retains water well, but has poor drainage. • Fine particle size • High pH • Pros: Rich in nutrients, retains water • Cons: Poor drainage, heavy and compact, hard to work with. If you’re working with natural soil, chances are it won’t be perfect for growing cannabis—not from the start, at least. The texture may not be optimal or it may have poor drainage, for example. But you can improve any type of soil by adding amendments, most of which can be found in your local grow shop.
These light fibres provide excellent water retention and can lighten compact soils. Some use a pure coco substrate with special nutrients to cultivate their weed. But to amend existing soil, it’s a good idea to add anywhere up to 30% coco coir, depending on the composition of your base soil. Perlite consists of very light, bright-white rocks that greatly improve the drainage and airiness of the soil. You can add more, but then your soil may become too light and nutrients may leach out. Good-quality commercial soils often come with added perlite. Vermiculite, just like perlite, is a heat-treated mineral you can use to make your soil lighter. Although vermiculite shares some characteristics with perlite, the two have opposite uses: Use perlite to increase drainage and airiness, and use vermiculite to increase water retention. Luckily, you can use both, as perlite and vermiculite work well together. Worm castings are normally seen more as a nutritional soil amendment as they contain a plethora of useful microorganisms that benefit growth. But worm castings will also improve the texture, drainage, and water retention of your soil. When amending your soil with worm castings, use about 25–30%. If your DIY cannabis soil is rich in organic material, you will likely not need to add nutrients to it. As a matter of fact, some growers make the mistake of adding manure and vegetable scraps to their soil to "fertilise" it. This results in soil getting “too hot” for the plants, hurting their development in turn. If you want to put your vegetable scraps to good use in your garden, you first need to compost them. If you think you need to amend your cannabis soil with nutrients, you can easily purchase bottled solutions tailored to a plant’s phase of growth. One factor to consider when choosing the right soil for your weed is whether you’re growing photoperiod or autoflowering plants. Autoflowers prefer a light mix with fewer added nutrients. A great substrate for your autoflowering ladies is a 50:50 mix of coco coir and a light, peat-based soil with some added perlite for drainage. When growing autoflowers, stay away from heavily fertilised soils and certain amendments like bat guano, as these will be too hot and overload your plants with nutrients. The same is true for cannabis seedlings, which do not like high levels of nutrients. Plant autoflowers in their final growing container in a cup-sized hole in the centre of the soil. Fill the hole with seedling/starter soil with no nutrients and place your seed in it.
This way, your seedling can grow without being surrounded by the hot soil, which would otherwise burn it. For photoperiod plants, start them out in small seedling pots/cups with soil that has little to no nutrients. More mature plants will tolerate higher nutrient levels much better than seedlings. If you’ve just started growing cannabis, it may be best to simply get ready-made soil from the grow store. The reason for this is that good-quality cannabis soil normally contains everything your plants need for healthy growth, in the optimal ratios. If you want, you can further improve your store-bought soil with a handful of perlite for increased drainage, but otherwise you should be good. On the other hand, there may come a time when you want to make your own soil. After all, why spend good money on soil if your homemade version is even better? Here is a recipe for a basic homemade cannabis soil.
• 1 part vermiculite • 1 part coco coir peat • 2 parts compost • ½–1 cup worm castings (or humus) DIRECTIONS. Check the directions of the product to see what kind of volume you will be getting. Use a bucket and mix the coco coir peat with the vermiculite. The above is a basic soil recipe that will serve you well for most grows, indoors and outdoors. But you can further enhance your soil mix by adding organic fertilisers.