Cathy has a problem with no-hole flats. "These come each with a clear cover (to retain humidity) but no holes in the bottom of the flats. Some flats have holes and some don't. I never did understand this distinction. Do I only need to punch some holes in the flat bottoms if I intend to water from the bottom (from a tray or mat)? Are the flats w/o holes for people who top-water? Thanks!" Flats without holes are better for holding small pots in a humid environment. Especially good if you stand the flat on your window sill. If using the flat directly, better to have holes whether you water from top or bottom. If you decide to drill holes in the flats you've got, use a lower speed setting on your drill, if it has one, have the flat on a solid flat (no pun intended) surface such as a block of wood and do NOT press down hard when drilling or you may split the plastic bottom badly and lose the flat altogether. Remember the engineer's adage: "Let the drill do the work." Regards Hamish