Tomatoes should be a respectable size in 4 weeks. Cucumbers, squash, zucchini, pumpkins (or mini pumpkins) would definitely be ready. Beans. Lettuce. Swiss chard (I love the "Bright Lights" variety). And I agree with Karen about the zinnias, marigolds and basil -- they germinate fast and would be a nice size in a month. Maybe nasturtiums, too. That should give you enough to keep busy!
