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what is best seed starter soil for cannabis indoors

It also contains great organic ingredients that promote growth and increase water and nutrient uptake.

So IT can either be loamy and Sandy, Clay and loamy, or Sandy and clay and, in other cases, a combination of the three.

Product Specifications

Cannabis does still have some differences, such as getting the appropriate amount of macronutrients, micronutrients, and minerals as well.

However, that doesn’t mean that you should just throw your seed in the backyard and hope for the best.

Table of contents

For photoperiod plants, start them out in small seedling pots/cups with soil that has little to no nutrients. Replant after a few weeks. More mature plants will tolerate higher nutrient levels much better than seedlings.

Cannabis soil needs to have excellent drainage. When you water your plants, it shouldn’t pool on top of the soil. If the soil has poor drainage, your plants will get sick and turn out subpar yields, or die.

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 you’re growing without additional nutrients, your soil needs to contain organic substances such as humus, compost, worm castings, guano, etc. Microorganisms in the soil will turn these substances into nutrients for your plants to access on demand.

Just as important as good drainage is water retention, which is the soil’s ability to hold water. Good cannabis soil has an optimal balance of water retention and drainage.

Cannabis prefers a light and loose soil texture. A light texture promotes root development, and it ensures more oxygen reaches the roots for optimal growth and health.

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.

The flowering mix is the same except that i add High Phosphorus Guano, in my case, Jamaican.

I use sunshine #4 (Soilless mix) for starting, and i cut my Ocean Forest with Sunshine #4 for vegging.

2 parts Sunshine #4
1 part Ocean Forest (Happy Frog works great too)
Mycorrhizal fungi inoculant
Earthworm castings.
Dried Kelp
Jamaican Bat Poop (In the flowering mix)

That mix lightens up the Ocean Forest, and improves drainage because of all the perlite in Sunshine #4. The Myco inoculant is already in Happy Frog, but it’s not in Ocean Forest, so i add it. The Jamaican Bat Guano increases the phosphorus, because i’ve always thought that Ocean Forest just didn’t have enough Phos to finish up the buds. You’ll still need the occasional Micro-nutrient.