Crop at a Glance
Growing season: Summer
Time of planting: Spring after date of last killing frost
Spacing: 2 vines per hill and 4 to 5 feet between hills
Days to harvest: Summer squash—60 to 70 days; winter squash—90 to 135 days
Average yield: Summer squash—10 to 15 fruit per vine; winter squash—4 to 8 fruit per vine
Common starting method: Seed or transplant
There are few vegetables easier to grow in the home garden and more versatile in form/use/consumption than squash. The term “squash” refers to several plant species native to Central and South America. Many squash types or cultivars can be grouped as summer squash or winter squash, depending on the season the vegetable is harvested.
Selecting Types to Plant
Select squash types that appeal to both your culinary and esthetic tastes. Summer squashes include zucchini, yellow crookneck (Figure 1), and pattypan. Familiar winter squashes include acorn, butternut (Figure 2), buttercup, turban (Figure 3), Hubbard, curshaw (Figure 4), and spaghetti. Pumpkins are considered a type of squash, as are gourds. Gourd plants bear inedible fruit best suited for decorative purposes (Figure 5). Be sure to select a squash that matures within the growing season of your geographic area (see WSU’s Home Vegetable Gardening publication EM057E, https://pubs.wsu.edu/ItemDetail.aspx?ReturnTo=0&ProductID=15566). Most summer squashes require 60 to 70 days from planting to first harvest. Winter squashes require between 90 to 135 days, and this may be longer than some areas in Washington allow.
Choosing a Planting Site
Squash grows best in fertile, well-drained soils with high levels of organic matter and full sun exposure. Since squash thrives in a soil pH ranging from 6.0 to 7.5, it would be prudent to have your soil tested at the planting site prior to
Squash can be started in the garden from seed. We recommend that you purchase certified seed from seed catalogs and garden centers, as seed saved from last year’s harvest is unlikely to produce the same type of squash as the parent plant. Beware: Squash is a frost-tender vegetable. Seeds may not germinate in cold soil and seedlings can be killed off by spring frosts. Squash is planted in hills (mounds of soil) about 4 to 5 feet apart. Sow 4 to 5 seeds per hill at a depth of one inch in mid- to late May, depending on the date of the last killing frost (see WSU’s Home Vegetable Gardening publication EM057E, https://pubs.wsu.edu/ItemDetail.aspx?ReturnTo=0&ProductID=15566). Later, as the plants develop 2 to 3 leaves, thin to a couple of well-spaced plants per hill. Alternatively, start plants in the home or greenhouse 10 days to 2 weeks prior to transplanting seedlings into the garden. Spacing is important when planting these seedlings; place 2 seedlings per hill spaced 4 to 5 feet apart.
The first couple of weeks after planting are critical to the survival and productivity of squash. If seeds fail to germinate, or germinate unevenly, you should investigate why (planted too deep, cold soil, old seed, pest-damaged seed, etc). Familiarize yourself with the appearance of normal, healthy plants and periodically (2-3 times a week) observe your plants for any signs of stress or pests. The most common sign of stress is leaf-wilting associated with either too little or too much water. Check the moisture level of the soil near the root zone of the squash plant: It should be moist and pliable, not dry and crumbly or wet and dripping. Watch out for stunted plants with pale leaves or for vigorous plants that fail to bloom or set fruit. These are signs of low soil fertility or excessive soil fertility. Another key period for maintenance is flower bloom. For most squashes, the male and the female flowers (distinguished by the round chamber at the base of the flower) are on the same plant. These flowers are dependent on honey bees and other bees to transfer the male pollen to the female flower. Take precautions to minimize insecticide use during flower bloom and encourage bee access and visitation. Inadequately-pollinated female squash flowers may grow, but abort before full fruit development.