Squash, Summer Growing Guide

Also known as zucchini, yellow squash, scalloped squash, patty pan squash. Summer squash comes in a variety of shapes and colors. Bush varieties take up relatively little space and if kept picked will keep producing right up to frost.

Site Characteristics

Sunlight:
 full sun
Soil conditions:
 requires well-drained soil and high fertility
 Prefers well-drained, fertile, loose soil, high in organic matter with pH between
5.8 and 6.8. Plentiful and consistent moisture is needed from the time plants
emerge until fruits begin to fill out.
Special locations:
 outdoor containers; requires large container and frequent watering

Plant Traits

Lifecycle: annual; tender annual
Ease-of-care: easy
Height: 1 to 3 feet; most summer squash grow on compact vines in contrast to the sprawling vines of most winter squash and pumpkins.
Spread: 2 to 4 feet
Bloom time:
 mid-summer
 late summer
 early fall
Flower color: yellow
Foliage color: medium green; some varieties have interesting "water marks" on their foliage.
Foliage texture: coarse
Shape:
 cushion, mound or clump
 climbing/vine
 most summer squash varieties form a compact, bushy vine.
Shape in flower: same as above

Growing Information

How to plant:
 Propagate by seed
 Germination temperature: 60 F to 105 F—will not germinate in cold soil. Wait to plant until soil reaches at least 65 F—preferably 70 F or more. Germinates best at 95 F.
 Days to emergence: 5 to 10—should germinate in less than a week with soil temperature of 70 F and adequate moisture
 Seed can be saved 6 years

Maintenance and care

Squash like warm soil and are very sensitive to frost so don’t be in a rush to plant early in spring. Wait until danger of frost has passed and soil has warmed to about 70 F or about 2 weeks after the last frost date.

Direct seed ½ to 1 inch deep into hills (which warm and drain earlier in the season) or rows. Sow 4 to 5 seeds per hill. Space hills 3 to 4 feet apart. When the plants are 2 to 3 inches tall, thin to 2 to 3 plants per hill by snipping off unwanted plants without disturbing the roots of the remaining ones. In rows, sow seeds 4 inches apart in rows 4 to 5 feet apart. Snip off plants to thin to one plant every 12 to 24 inches.

For extra early crops, start inside in 2- to 3-inch pots or cells 3 to 4 weeks before transplanting outside. Sow 3 or 4 seeds per pot and thin to one or two plants by snipping off the weaker plants to avoid damaging the roots of those that remain. Harden off by cutting back on water and reducing temperature before transplanting. Plant transplants out in the garden about 1 to 2 feet apart after all danger of frost has passed. To hasten first harvest by as much as 2 weeks, use black plastic mulch to warm soil before direct seeding or transplanting. Early fruits are sometimes wrinkled, turn black or rot due to poor pollination. At the end of the season, remove or till in vines to reduce mildew. Use row covers to protect plants early in the season and to prevent insect problems. Remove cover before flowering to allow pollination by insects or when hot weather arrives.

Mulching plants helps retain moisture and suppress weeds. Mounding soil around the base of the plants can discourage squash borers from laying eggs.

Pests

Squash bug—Hand pick. Bury or compost plant residues after harvest.
Squash vine borer—Remove by hand and destroy.
Striped cucumber beetles—Construct tents of fine netting or cheesecloth or use floating row covers over young plants. Put in place at planting and remove at flowering. Control of beetles may be a factor in preventing bacteria wilt.

Diseases

Bacterial wilt (Erwinia tracheiphila )—Remove and destroy infested plants. If striped or spotted cucumber beetles appear, control as soon as possible.
Powdery mildew—Avoid wetting foliage if possible. Water early in the day so that aboveground parts will dry as quickly as possible. Avoid crowding plants and eliminate weeds around plants and garden area to improve air circulation.
Scab—Avoid wetting foliage if possible. Water early in the day so that aboveground parts will dry as quickly as possible. Avoid crowding plants and eliminate weeds around plants and garden area to improve air circulation.
Viral disease—Remove and destroy entire infested plant along with immediately surrounding soil and soil clinging to roots. Eliminate wild cucumber and milkweed nearby. Plant variety Multipik to mask symptoms on fruit. Control aphids early in the season by washing off with water as needed early in the day. A hard stream of water can be used to remove many aphids.

Other diseases:
Downy mildew

Varieties

There are four groups of summer squash:

Yellow summer squash have long, thin fruits that can be smooth or warty, straight or crook-necked.
Zucchini types are also long and cylindrical, often dark green but some varieties are lighter, yellow or even white.
Scalloped or patty pan squash look like disc-shaped UFOs. Their edges are scalloped and colors range from greenish to yellow to white.
Mideast or Cousa varieties have fruit that is shorter and thicker than zucchini, usually with a pale green skin.