Posted: 09/04/2013 at 11:58
I grow my toms under glass in a long tray filled with gravel, and as Verdun mentioned, when watering I try not to splash the leaves - removing the lower ones helps here. It helps to avoid blight, but isn't bullet proof, unfortunately.
The gravel allows for free drainage, but also as a sump from which the plants can take up more water if they need it.
Works for me anyway!