Summer Squash

Few plants are as productive as summer squash. They grow quickly, provide a continuous harvest, and they shade the ground under their prickly leaves, making it an excellent foodscape plant.

Summer squash (Stearns Farm CSA) CC BY-ND 2.0

Summer squash vs. winter squash
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All squash plants are cucurbits, along with gourds and cucumbers. Squashes are classified as either summer or winter varieties. The main difference between summer squash and winter squash is when it is eaten. Summer squashes, which are generally eaten immature, have thin, tender skins, while winter squashes have hard skins that allow them to be stored for longer periods of time. Common winter squashes include pumpkins, Hubbard, acorn, and butternut squash.

Types of summer squash

There are two main types of summer squash: zucchini and yellow, but these are divided up into several different varieties:

• green zucchini - the classic
• yellow (or golden) zucchini - no tapering, straight cylinder
• Romanesco zucchini - stays tender even when it reaches horse leg proportions
• straightneck yellow - tapers at the stem end
• crookneck yellow - tapers at the stem end with a crook
• pattypan - scalloped disks
• cousa - shorter and stubbier than zucchini
• zephyr - a cross between yellow crookneck and yellow acorn
• eight ball - a spherical zucchini

How to grow summer squash

Summer squash prefers a sunny, well drained area, with a pH of 5.5 to 6.5, so acidification may be needed. Squash seeds are very large and should be planted about an inch deep in May and June. [The basic rule of thumb for the planting depth for any seed is to use the longest length measurement of the seed and bury it that deep.] Keep the soil moist until germination occurs, but do not let it stay soggy or damping off disease may kill your squash seedlings. Squash plants generally do not take kindly to transplanting, so it is better to plant the seeds where you want them in the first place.

​These plants will take up some space, though they can be grown in containers, towers, and straw bales, and they love raised beds! Squash is a traditional member of the Three Sisters Method of growing beans and corn in a mutually beneficial garden design. Generally, winter squash vines can get very long, while most summer squashes have more of a mounding growth, though this isn’t always the case. Be sure to read the seed packet for variety-specific information. Squash is a relatively light feeder, so fertilizer is rarely needed. These plants generally get enough nitrogen from the soil. Too much nitrogen will encourage plenty of leaves but very little fruit. Of course, adding some aged compost around the plants as mulch certainly wouldn’t hurt!

Summer squash pests and diseases

If you look at a list of all the pests and diseases that affect summer squash, you’d wonder how these plants survive at all. But they do. In fact, they thrive! But it’s always a good idea to know what might happen, so you can nip it in the proverbial bud before things get out of hand. Common summer squash pests include aphids, armyworms, cutworms, redhumped caterpillars, leaf miners, loopers, cucumber beetles, nematodes, grasshoppers, slugs and snails, stinkbugs, wireworms, earwigs, and various beetles. Squash bugs are generally your biggest threat and they make themselves known in July in the Bay Area. As far as I know, squash vine borers have not yet made their way over the Rockies, but be forewarned! Row covers go a long way toward protecting your summer squash plants against these pests. Summer squash diseases can categorized by the pathogen:

• Fungal - verticillium wilt, powdery mildew, Fusarium crown and foot rot, and belly rot
• Bacterial - angular leafspot
• Viral - cucurbit yellow stunting disorder (spread by whiteflies), squash mosaic, zucchini yellow mosaic, and curly top

Environmental conditions, such as irregular watering, can cause blossom end rot, bitter fruit, and blossom drop. Poor pollination can also be a problem. Despite all these threats, summer squash plants nearly always produce an astounding amount of food.

Summer squash (Kate Russell)

Harvesting summer squash

Squash plants can run amok and get away from you. Everyone has a story of the monstrous zucchini they swore wasn’t there the day before. It happens. When it does, stuff it with sausage and onions, or make some chocolate zucchini cake. One nice thing about summer squash is that it can be harvested at any stage in its development. Simply cut the stem and enjoy the fruits of your labor! Once you’ve harvested a summer squash, you can add it to stir fry, salads, soups, stews, or just nibble on it while reading a good book. Odds are, another one will be ready to harvest in a day or two. Summer squash is particularly sensitive to ethylene gas, so you will want to keep them away from bananas and other ripening fruits.

One seed and a little water can provide you with a surprising amount of fresh food. Plant one today and see what happens!