What kind of drainage material should I use in the planter under the potting soil?
Growing Radishes and Lettuce Inside During Winter in WA
Certified GKH Gardening Expert
I have two personal preferences- My first being what is called growstone. This is a fluffed recycled silica glass material, and is one of the best options.
My second preference is expanded clay pellets. These are a very good dranage material as well.
Perlite would also work just fine as well. as would gravel that was WELL washed off.