zucchini and zucchini flowers
Updated: June 10, 2021

Planting summer squash facts

  • Hardiness: Very tender warm-season annual. Frost will injure top growth; needs warm weather to grow. 
  • Planting: Summer squashes (Cucurbita pepo) are warm-season plants. Sow seed directly into the garden after the danger of frost has passed and soil has warmed. Thin seedlings by cutting excess plants with scissors rather than by pulling leaving the single strongest plant. Get a jump on the growing season by planting seeds indoors in 3-inch diameter containers 3 weeks prior to planting time. Handle transplants gently and disturb the root system as little as possible. Plant a second crop July 1 - 15. Full sun requires direct light at least 6 hours/day; prefers 8 - 10 hours/day.
  • Days to maturity: 50 - 65 from transplant.
  • Spacing: Hills (two to three plants per hill) 3’- 4’ in-row x 4’- 6’ between rows; single plants 2’- 3’ in-row x 3’- 5’ between rows.
  • Fertilizer needs: Medium requirement for nutrients, either from soil organic matter or fertilizers. Incorporate compost or fertilizer prior to planting. Side-dress when female flowers begin to appear. Refer to Fertilizing Vegetables for details.
  • Approximate yield: 20 to 40 lbs. per 10-foot row. 

Common summer squash problems

Bacterial wilt
Choanephora Rot
Cucumber beetle
Downy mildew
Vegetables not true to type
Powdery mildew
Pollination problems
Squash beetle
Squash bug
Squash vine borer

Growing and care of summer squash (zucchini) 

  • Summer squash grows on non-vining bushes. 
  • Vigorous stems of sprawling plants will root where they touch the soil, increasing fruit production and helping plants withstand squash vine borer injury to main stems.
  • There are many varieties having different fruit shapes and colors. The three main types are: 
    1) yellow straight-neck or crooked neck; 2) white, saucer-shaped, scallop or patty pan; and 3) oblong, green, gray, or gold zucchini. They are harvested when immature and the rind is still tender and edible. 
  • Incorporate compost into the soil before planting. 
  • Seed or transplants can be planted through black plastic or landscape fabric to hasten maturity.
  • Watering - Water deeply and regularly at the base of each plant, especially during hot, dry weather and once the first fruits start to form.
  • Weeding - Remove all young weed seedlings by hand or with a hoe and use a mulch around plants to keep weed seeds from germinating.

Squash pollination

  • Members of the squash family produce male flowers for 1 to 2 weeks before female flowers appear. This is a normal growth habit and varies with cultivars. For a flower to develop into a fruit, pollen must be carried by bees from male flowers, on the same plant or on different plants, to the female flower (the one with the tiny squash below the flower). Poor fruit-set is common during rainy weather when bees are inactive. Avoid using any pesticides during the bloom period to reduce the risk of poisoning pollinators.
squash male and female flowers
Male and female squash flower examples

Harvesting

  • In addition to describing the time of planting, "summer squash" refers to their short storage life, compared to winter squashes. 
  • Harvest immature fruits, about 6- to 8-inches long and 1½ to 2 inches in diameter for elongated types; 3 to 4 inches in diameter for pattypan types; and 4 to 7 inches long for yellow crooked neck.
  • Check plants daily once they begin to bear fruit.
  • If the rind is too hard to be marked by the thumbnail, it is over-mature. Remove old fruit to allow new fruit to develop.

Storage and preservation

  • Will keep for 5 to 14 days in cool (32°- 50°F), moist (90% Relative Humidity) conditions.

Squash Flowers: So where are the squash?