As you shop for packs of seeds for your summer garden, remember that there are two distinct groups of squash that are used differently in the kitchen: summer squash and winter squash. Most vegetable gardeners will want to plant a few of each type to meet their needs.
Interestingly, summer squash and most winter squash are derived from the same species, Cucurbita pepo. The difference is simply that summer squash was developed to be especially tender and tasty well before it matures, when its skin is still thin and its seeds are barely visible. Zucchinis (courgettes) and pattypans are the best-known summer squashes. You harvest summer squashes regularly throughout much of the summer.
The name “winter squash” might throw a beginning gardener. It doesn’t mean it is sown or grown in winter. In fact, you sow it in late spring, when the soil warms up, just like summer squash. The difference is that it can be stored for long periods, well into winter.
Winter squash is harvested when it is fully ripe, in late summer or fall. By then its skin will be hard, its flesh dense and less watery and its seeds (which are also edible!) will be fully mature. Of the many the squashes derived from C. pepo, the best known are probably pumpkins, vegetable marrows and spaghetti squashes.
There are also other squash species that produce winter squash, notably C. moschata (crookneck squash, butternut squash, etc.) and C. maxima (buttercup, Hubbard and others).