Zucchini and summer squash

About Zucchini and summer squash

Zucchini and other summer squash, like yellow crookneck and pattypan, are picked young while the skin is still tender. A few plants produce plenty, as long as you keep picking.

Grown as a warm-season annual in every zone; it is killed by frost, so plant it out after the danger of frost has passed.

When to plant

Timing is counted from your average last spring frost (and first fall frost). Sow & Tell works out the actual dates for your ZIP code.

• Start seeds indoors: 2 to 4 weeks before the last frost
• Set out plants: 2 to 3 weeks after the last frost
• Sow seeds outdoors: 1 to 2 weeks after the last frost
• Fall planting: 11 to 12 weeks before the first fall frost

Days count from seeding. Sow about 1/2 inch deep once soil reaches 70F at 2 inches deep.

Soil

Moisture-retentive but well-drained soil; raised beds help drainage.

Have the soil tested and keep pH 6.0 to 6.5; work in compost or well-rotted manure, and add phosphorus and potassium only as the soil test says.

Feeding

• when plants begin to spread out their vines: nitrogen fertilizer such as 46-0-0 or 27-3-3. Use about 1/2 cup of 46-0-0 or 1 cup of 27-3-3 per 100 ft of row beside the plants and water it in.
• after plants flower and small fruits form: fertilizer as your soil test advises, such as a nitrogen fertilizer. Side-dress beside the plants and water it in.

Never use weed-and-feed products on vegetables, and skip extra phosphorus unless a soil test calls for it.

Harvest

Pick while small, before the seeds get large and the skin hardens; small 'baby' fruits are the most tender.

Pick often; leaving oversized fruit on the plant cuts yield, so remove big ones even if you won't use them. Plant again about 3 weeks later to extend the harvest.

Varieties (44)

Good neighbors

Nasturtium, Marigold, Sweet alyssum

UMN Extension says research supports nasturtiums for fewer squash bugs, an Iowa study found nasturtiums and marigolds reduced squash bug and cucumber beetle damage, and marigolds with sweet alyssum drew in aphid enemies.

Pests to watch for

Squash vine borer, Squash bug, Cucumber beetles, Pickleworm, Aphids, Corn earworm (tomato fruitworm), Flea beetles, Whiteflies, Leafminers, Harlequin bug, Squash beetle, Corn rootworms, Garden symphylan, Seedcorn maggot, Melonworm, Groundhog (woodchuck)

Diseases and problems

Powdery mildew, Cucurbit viruses, Anthracnose, Angular leaf spot, Choanephora fruit rot, Poor pollination, Hail and wind damage, Ozone injury, Blossom end rot, Sunscald, Frost and freeze injury, Gummy stem blight, Verticillium wilt, Downy mildew, Bacterial wilt, Damping-off, White mold, Sooty mold, Cucumber mosaic, Zucchini yellow mosaic, Squash mosaic, Watermelon mosaic, Curly top

In the kitchen

Grilled, sauteed, roasted, grated into breads, or spiralized; the blossoms are edible too.

Keeping it: Refrigerate unwashed zucchini and summer squash in the crisper and use within about a week. Smaller, fresher squash keep and cook best.

Pets: Listed as non-toxic to dogs, cats and horses (ASPCA).