Plant Pole Beans
Bush beans may be wonderfully productive, but I don't think they match the flavor of pole beans. Pole beans also make great use of space since they grow vertically. Arrange your planting so that tall beans can shade heat-sensitive plants.
Promote Buzz Beacons
Many members of the Umbellifera family, including carrots, parsley, dill, and Queen Anne's lace, make great magnets for beneficial insects. Allow these plants to flower, and watch the braconids and other little buzzers appear in droves.
Clip the stem tips from chrysanthemums to force out side branches. This makes the plants much bushier and doubles the number of flowers that appear in late summer. Also pinch back asters, Mexican bush sage, and other late bloomers.
Adopt a basil seedling or two at the garden center for your first planting. Then sow some basil seeds so you'll have vigorous young plants when the first ones insist on producing flowers rather than leaves. Gather basil stem tips often to help promote the development of lots of leafy branches.
Seed Summer Squash
You will need at least four plants to insure good pollination of squash flowers, but small plantings help keep the harvest manageable. I easily fit four plants into a two-by-four foot bed, and allow the plants to sprawl over the edges as they grow.