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How to Grow: Summer Squash
Learn about growing summer squash and the best organics controls for the squash vine borer insect.
Listen to podcast:
How to Grow: Summer Squash
You’ve got to watch out when growing summer squash (Cucurbita pepo) and zucchini. When it’s ready to harvest, you’ll get so many fruits so fast you’ll be begging neighbors to take it away. I’ve even heard of people dropping extra zucchinis through opened windows in unattended cars just to move the stuff. Yes, summer squash and zucchini has a reputation for being prolific. That’s a good thing for a new gardener, because it’s so satisfying to be able to offer extra produce to friends and family.
Summer squash and zucchinis come in a variety of skin colors and sizes. The skin can be dark green, light green or yellow colored. The shape long, crooked neck, scalloped or round. All have white-colored, mild tasting flesh making them perfect shredded raw in salads, baked in breads, sauteed with other vegetables or added to stews or casseroles. I love to pick the flowers and saute them with garlic and olive oil. It’s as versatile as it is easy to grow.
When to Plant
Summer squashes are warm weather loving crops, so don’t rush them into the garden in spring. Either directly sow seeds or transplant seedling after all danger of frost has passed — usually May. To get a jump on the season, buy transplants from local garden centers or start seedlings indoors 4 weeks before planting outside.
Where to Plant
Plant summer squash in full sun on well drained, fertile soil. Unlike winter squash and pumpkins, these plants stay bush-like, so are great for a smaller garden. I like to lay black plastic mulch down over the bed 2 weeks before planting to preheat the soil. I poke holes in the plastic to sow seeds or plant seedlings. This gives them a jump on the growing season, prevents weeds from growing, and keeps the soil moist.
How to Plant
Summer squash like a fertile soil, so amend the bed well with compost prior to planting. Plant seeds or seedlings 2- to 3-feet apart in rows spaced 4-feet apart. Summer squash don’t like cool spring air temperatures, so consider covering the planting with a floating row cover during cool nights.
Care and Maintenance
Keep plants well watered and weeded, especially early in the season until the plants get established. Once established, if not growing in black plastic mulch, spread a layer of an organic mulch, such as straw or untreated grass clippings, around plants. When they start flowering, add a small handful of an organic fertilizer, such as 5-5-5, around each plant.
Summer squash are susceptible to a number of insects such as cucumber beetles, squash bugs, and squash vine borers. See pumpkins for more on controlling these pests.
The mantra with picking summer squash is early and often. Start harvesting young squash when they are 6-inches long. Harvest patty pans or scalloped squash when they are 3-inches in diameter. The more you harvest, the more it will produce. If you make the mistake, like I do every year, and forget to harvest for just a few days, you’ll discover some large squash clubs in the garden that are better used as bowling pins than food! They actually can be stuffed and baked, so even large summer squash have a use.
‘Yellow Crookneck’ is a classic yellow summer squash, while ‘Partenon Hybrid’ and ‘Raven Hybrid’ are good growing zucchinis. The Italian heirloom ‘Constata Romanesco’ has green and white striped and ribbed fruits and great flavor. I like the light green skin colored Lebanese or cousa summer squash such as ‘Magda Hybrid’. They have a sweet, nutty flavor. If you like the flying saucer squash (what kids like to call them), scalloped, or patty pans, try the yellow ‘Sunburst Hybrid’. For bowling (just kidding), try ‘Eight Ball Hybrid’. It has green skin and grows the size of a bocci ball. Let’s play!
Text excepted from the Northeast Vegetable and Fruit Gardening book.
Podcast Transcript: Squash Vine Borer
We’ve all seen this happen. Beautiful summer squash, pumpkin or winter squash plants are thriving in July, only to start wilting during the day, even if the soil is wet. After closer inspection you see holes in the plant base. Yes, it’s the squash vine borer. This destructive moth lays eggs in July at the base of these plants. The larvae burrows into the stem causing it to wilt. Severe infestations can kill your plant.
But all is not lost. If you catch the infestation early, you can physically remove the larvae and maybe save the plant. It’s time to play surgeon. With a sharp knife or razor slit the stem at the hole going away from the base of the plant. You’ll soon find the fat, white larvae. Remove it and feed it to your chickens. They’ll love it! Cover the slit with soil and water well. Hopefully the vine will reroot and survive. You can also inject B.t. organic pesticide into the stem with a syringe where you think the larvae is tunneling. The larvae will eat the B.t. and die without harming the plant or us.
Prevention, though, is probably the best cure. Plant resistant squashes, such as butternut. Cover young plants with a floating row cover until flowering. After flowering cover just the base of the plant with row cover to make a barrier to prevent egg laying. Delay planting zucchini and summer squash until early July to avoid the egg laying stage. Set out a small yellow pail with water in June to trap the day flying, moth. They’re attracted to the yellow color and drown in the water. Remove infested plants and rotate crops each year.
From the Vermont Garden Journal on Vermont Public Radio.