All About Growing Summer Squash

Pattypan squash are an old type of summer squash that produce fruits shaped like plump flying saucers with scalloped edges. Varieties range from dark green to bright yellow to white.

Round and oval squash produce single-serving-sized fruits on compact, bushy plants suitable for large containers or intensive raised beds.

Tromboncino and zucchetta squash (C. moschata) produce large, curvaceous fruits with light green skins. Naturally resistant to insect pests, these rowdy, vining plants grow best on a trellis.

For more information about types of summer squash and our recommended varieties, see our Summer Squash at a Glance chart.

When to Plant Summer Squash

Sow summer squash seeds in prepared beds or hills in spring after all danger of frost has passed. You can also sow seeds indoors under fluorescent lights and then set out the seedlings when they’re 3 weeks old. In Zone 5 and warmer, you can sidestep early-season squash bugs by delaying the planting of seedlings until early summer. Stop planting summer squash 12 weeks before your average first fall frost date.

How to Plant Summer Squash

Choose a sunny site with fertile, well-drained soil with a pH between 6.0 and 6.5 for growing summer squash. Spots that were previously occupied by compost piles are especially desirable, or you can dig two heaping spadefuls of compost into each planting site. As you dig, loosen the soil to at least 12 inches deep and mix in a light application of a balanced organic fertilizer.

Plant summer squash seeds 8 inches apart, poking them into the soil 1 inch deep; water well. Thin seedlings to 3 feet apart. (If using transplants, set them out 3 feet apart.)

To prevent insect damage, install protective row covers over your squash as soon as you’re done planting. Read The No-Spray Way to Protect Plants for more tips about using row covers.

How to Grow Summer Squash: Boost Production

Summer squash produce male flowers on bare stems, while female flowers?—?usually preceded by the males?—?show a tiny squash at their base. You can improve yields in small plantings (fewer than five plants) by using a small paintbrush to spread pollen from male to female flowers, supplementing insect pollination.

Harvesting and Storage

Summer squash blossoms are edible, and you can harvest fruits from baby-sized up until they toughen with age. Harvest at least twice a week, using a sharp knife to cut fruits (leave a small stub of stem attached). Promptly wash fruits in cool water and store in the refrigerator. For long-term storage, freeze or dry blanched pieces of summer squash.

Saving Seeds

With the help of bees and other pollinators that fly long distances, summer squash plants readily cross with one another, which doesn’t affect the current season’s crop but will change the genetic code carried in the seeds. Summer squash also cross with several varieties of winter squash that are of the same species (C. pepo), such as acorn or delicata squash. To grow summer squash for seed-saving purposes, set aside a hill where you can grow two plants of the same open-pollinated variety together. When the plants begin to bloom, cover them securely with a tent made of row cover or tulle to exclude pollinating insects. For a two-week period, hand-pollinate female flowers during the morning hours and promptly replace the tent. When three perfect fruits have set on each plant, remove covers and pinch off new flower buds until the seed-bearing fruits are fully ripe (with hard rinds and brown stems). Save and dry the largest seeds from the insides of each fruit. In good storage conditions, summer squash seeds will remain viable up to six years.

Pest and Disease Prevention

All types of summer squash face challenges from insects, including squash bugs, squash vine borers and cucumber beetles. To defend your plants from all three pests, cover them with row covers held aloft with stakes or hoops until the plants begin to bloom. Big, healthy plants will produce well despite pest challenges.

Powdery mildew is a late summer disease best prevented by growing resistant varieties, which often have the letters PM (for “powdery mildew-resistant”) after their variety name.

Growing Summer Squash Tips

Wait until the weather warms to grow summer squash, otherwise your plants will sulk in cold soil. Also, try growing summer squash around a compost pile located along the edge of your garden.

Choose hybrid varieties if you need a space-saving bush plant or a special form of disease resistance. Open-pollinated varieties often grow long vines that produce for an extended period of time and that may send out supplemental roots where the stems touch the soil.

Grow at least two different colors of summer squash each season for more colorful pizzas and prettier casseroles.

Cooking With Zucchini

Colorful and low in calories, summer squash offer quiet flavors that blend beautifully with fresh herbs, mushrooms and all sorts of cheeses. When freezing blanched squash, include chopped herbs and fresh greens or cherry tomatoes for added color and flavor. Grilling enhances the flavor of both fresh and frozen summer squash. A bumper crop will fill a freezer; drying blanched squash pieces will save storage space and give you high-quality veggies for winter soups and stews. Grate slightly overripe zucchini and use it in baked breads and muffins. All summer squash provide vitamins A and C along with dietary fiber. Many of the nutrients are most abundant in the squash skins.