I recently recieved dwarf pom seeds. I was looking at the instructions, and they say that the soil I need is "slow draining" and a sandy mix to go on top. What is "slow draining"? When I looked up growing instructions online, it just said "soil". Would normal potting soil work as long as the pot has drainage holes? They would be inside, under a lamp, near a window! Thanks!! I am pretty sure finding soil would have been easier in the summer!