Summer squash are a subset of squashes that are harvested when immature, while the rind is still tender and edible. These tasty, wholesome vegetables are easy to grow, and so productive that even a small planting usually yields an abundant harvest. By following some simple guidelines for proper planting, you can grow summer squash on a trellis, and enjoy their bounty all summer long. How to : Sow the squash seeds 2 to 3 inches deep, planting four to five seeds 3 to 4 inches apart in the soil...