To keep the ground cool while the seeds are germinating, shade it by placing a board over your rows, raising it off the ground with two flowerpots or bricks. Or use shade cloth or even sheer curtains to help keep the plants cool. When the seedlings emerge, remove the board, then mulch the ground with a half-inch of grass clippings or straw. Add more mulch once the seedlings are 1 to 2 inches tall.
Summer means cantaloupes, honeydews, and watermelon. Plant them now to give ’em a good start.