Hi Roland

check out Top 10 Marijuana Pot Growing Tips | Tips for Growing Indoor Marijuana, Cannabis, Ganja, Weed and Pot Plants for some soil tips. i have used something similar to the recipe for soil (subbing manure for the bat sh*t and seaweed) with decent results. i'm also trying a Batmix (premixed soil) available from any grow shop.
I wouldn't worry too much, once the soil has good drainage, you should be fine.
Happy growing :hippy: