The quickest and best way to know if you have enough spores is to plant then take a sample of the roots and have it tested for mycorrhizal colonization. No matter how many spores you add, they must colonize roots to be successful. Low to no colonization rates can occur if spores are not within close range of roots when they germinate. If they are not in close proximity to roots, they will die. If your soil is in good health, the mycorrhizal colonization process happens naturally. If you get the fungal and bacteria counts in balance and have good numbers of protozoa, mycorrhizal colonization will take place without any product inputs.