SOIL
PRO-MIX HP (high porosity) is a blend of mainly sphagnum peat moss and course perlite - and it's the only soil I use. I don't recommend adding anything to it, adding fertilizer is not necessary and will increase your risk of mold dramatically.
It's high percentage of pearlites provide excellent drainage & air flow, giving microgreen roots the perfect environment to grow quickly and evenly. It also holds moisture without getting soggy.
Soil is one of the biggest costs per tray when growing microgreens, especially in the beginning when you are purchasing it by the bag. Therefore, as you scale you will want to buy in bulk (a pallet of 30 cubes) from a distributor to lower your costs and increase your profits.
Need a pallet?
This is a link to purchase on Amazon. Many Ace Hardware, Lowes, Home Depot, and Walmart stores can order PRO_MIX HP for you.
Organic Option:
ProMix HP is not an organic growing medium. If you are looking for an organic option, ProMix MPO AGTIV REACH is a good choice.
Small Bag Option:
If you are just starting out and only growing a few trays or just want to try growing microgreens, PRO-MIX HP is available in a smaller 2.8 cuft loose fill bag as well.
