Jane, I prefer to use ordinary window screen, not only for flats but to place inside the bottom of the Anderson band pots to keep the soil from falling out. Bulbs seem to love the band pots with screen in the bottom as it improves drainage, and it gives some air circulation to the bottom of the potting mix without letting it dry out too quickly. And it's nice to look at all the happy little roots coming out through the screen. Screening is cheap if you buy it, or no cost if you salvage old screens from the dump like I do. And it lasts forever. Might not be suitable for your kitchen requirement, however, but we're here to grow bulbs... --Roy NW of Boston First frost predicted for tonite Massonia pygmaea is blooming, along with lots of oxalis