How to Plant and Grow Summer Squash

Among the easiest to grow and most productive plants in the vegetable garden, summer squash comes in an array of colorful varieties and different shapes. Zucchini, crookneck, and pattypan squash are the most popular but there are other, more unusual tasty choices worth growing in your garden. Try ‘Cousa’, a short and squat Middle Eastern variety that is mostly used for stuffing, the climbing Italian summer squash ‘Trombetta’, or the French round ‘Ronde de Nice’. Squash plants produce tender edible blossoms, too, so you are in for a special treat even before the fruit ripens. 

Whichever type of summer squash you grow, keep in mind that it’s a warm-weather crop. You need to wait for balmy spring weather to plant it. And always leave some space for flowering plants nearby to attract bees, which are indispensable for the pollination of summer squash.

Where to Plant Summer Squash

A spot in full sun with rich, fertile, well-drained soil is a must for growing summer squash. In terms of pH, the plants are adaptable and grow in slightly acidic to slightly alkaline soil.

It is very important to match the summer squash variety to your available space. Also take into consideration neighboring plants and pair summer squash with suitable companion plants. Crowded plants set the scene for disease and pest problems. Some varieties of summer squash grow in a large clump or as a bush type, while other varieties vine and sprawl. Although vining varieties can be trained up a sturdy trellis or arbor, they grow so fast that you might still find vines sprawling through the garden.

How and When to Plant Summer Squash

Summer squash is planted by either direct seeding it outdoors or by starting the seeds indoors in pots about 4 weeks before transplanting. This is recommended for cooler climates as it gives you a head start on the growing season. Summer squash seeds won’t germinate in a soil temperature lower than 60 degrees F.

To prevent over-planting, keep in mind that summer squash is a heavy producer so you don't need to plant a lot of seeds.

To plant seeds outdoors, wait until the soil has warmed up and any danger of frost is past. Summer squash can be planted in rows or mounds. Vine-type summer squash needs considerably more space than bush types. Plant seeds 1 inch deep, 4 to 6 inches apart in a row. When seedlings are 4 to 6 inches tall, thin the plants 12 to 15 inches apart and only keep the strongest seedlings. To plant seeds in mounded hills, create a small soil mound about 2 feet in diameter. Space mounds 2 feet apart. Sow five or six seeds 1 inch deep and 4 inches apart in each hill. When seedlings are 4 to 6 inches tall, thin to the two strongest plants. The exact spacing depends on the variety; make sure to check the seed packages for details.

Have the trellis for vine-type varieties in place before planting to avoid damaging the tender roots of the seedlings.

Summer Squash Care Tips

Summer squash is one of the easiest vegetables to grow. And it is notoriously prolific, too.

Light

Choose a planting site that receives at least 8 hours of direct sunlight every day.

Soil and Water

Plant summer squash in rich, loose, well-drained soil. Before planting, it is always a good idea to work a 4-inch layer of well-decomposed manure or compost in the soil. The ideal pH for summer squash is between 6.0 to 7.5 but it is still fine in a soil pH of 8.0. 

Watering the squash regularly and deeply in the absence of frequent rainfall is crucial. Don't spray water directly on the foliage, as this encourages the spreading of fungal diseases.

Spread a 2-inch layer of mulch over the root zone to prevent soil moisture loss.

Temperature and Humidity

Summer squash is a warm-weather vegetable. The ideal growing temperature is between 65 to 75 degrees F. In temperatures below 60 degrees F, growth will slow down, and the same thing happens above 85 degrees F, plus the plant produces less in extremely hot weather.

Although summer squash tolerates a humid climate, hot and humid weather can lead to a more rapid spread of fungal diseases.

Fertilizer

Even if you grow summer squash in rich, fertile soil, it will need fertilizer. Once the plant starts flowering, or when vine-type variety starts to spread, add a 10-10-10 fertilizer or a complete all-purpose vegetable garden fertilizer and follow the directions for amounts and frequency.

Pruning

Especially vine-type varieties easily outgrow their designated space. Pruning is optional but recommended to keep the plant at a manageable size, improve airflow, and make picking easier. Snip off vines without fruit at the base, and cut those with developing fruit at one or two leaf nodes beyond the last fruit.

Pollination

Summer squash has male and female flowers on the same plant and it needs pollinating insects—honey bees and other bees—to transfer the male pollen to the female flower. The best way to ensure pollination is to plant flowers that attract pollinators, such as zinnias, nasturtiums, marigolds, or borage. Also make sure not to use any insecticides that could kill beneficial pollinating insects.

Potting and Repotting Summer Squash

 Compact bush-type summer squashes are suitable to be grown in containers. Use a heavyweight container that is at least 1 foot wide and deep. Fill it with well-draining potting mix and a few handfuls of compost. Plant a couple of seeds 1 inch deep in the center of the container. When the plants are 4 to 6 inches tall, cut of all but the strongest seedlings at the soil level (do not pull the extra seedlings out, which may damage the seedlings you want to keep).

Water container-grown squash at least daily, up to twice in hot summer weather. As summer squash is an annual, repotting is not necessary.

Pests and Problems

Summer squash is commonly affected by pests. Keep an eye out for squash vine borers, squash bugs, cucumber beetles, aphids, and whiteflies. Potential diseases include powdery mildew, squash blossom blight, cucumber bacterial wilt, and mosaic viruses. Rotating the crops in your garden and not planting squash and other cucurbits in the same location as the year before is an important step to prevent serious pests and diseases.

How to Propagate Summer Squash

Summer squash is propagated from seed. If you are growing an open-pollinated heirloom variety, it makes sense to collect the seeds for next year. The seeds of hybrid cultivars, on the other hand. won’t produce plants that are true to the parent and to get a predictable quality of summer squash, you’ll have to buy seed from a seed company. Follow the instructions for planting summer squash above.

Harvesting

Zucchini, crookneck, and straightneck summer squashes are best when harvested at a small size, about 6 inches long. Pattypan or scallop squashes are best when they are 3 inches in diameter. Check plants daily because the squashes grow quickly in warm weather. Pick the squashes when you can easily pierce the skin with your fingernail. Overmature fruit has a harder skin. If you miss some fruit, harvest them as soon as you discover them. The more you harvest, the more the plants will bear. 

Make sure to cut the fruit off the plants with hand pruners or a sharp knife instead of tearing them off, which risks damaging both the fruit and the plant.

Types of Summer Squash

'Early Summer Crookneck' Squash

This heirloom summer squash has a bent neck and yellow fruits with bumpy skin. The compact plants grow 24 to 36 inches wide and 24 to 30 inches high. 53 days to maturity

'Early Prolific Straightneck' Squash

For more than one reason, this is a very popular heirloom summer squash with bumpy, creamy yellow skin. It matures early, has a buttery, nutty taste, early maturity, and the small size (only 24 to 36 inches wide and 24 to 30 inches high) of the plants fits even in smaller gardens. The bumpy, creamy yellow skin. 50 days to maturity

'Black Beauty' Zucchini

The outer skin of this smooth, straight heirloom zucchini is dark green, almost black in color, and the flesh is a creamy white. It has a bushy growth habit, reaching only 12 to 24 inches in height. 50 days to maturity

Pattypan Squash

This tasty summer squash is known for its flying saucer-like shape. It comes in beautiful white, yellow, and orange colors. A popular variety is ‘Sunburst’, a deep golden yellow, flattened, rounded, summer squash with scalloped edges. The vigorous plant is quite productive. 50 days to maturity

‘Zephyr’

This visually striking hybrid summer squash is yellow with faint white stripes and light-green blossom ends. The flowers of this tasty squash with a nutty flavor and firm texture are also edible. 54 days to maturity

'Raven' Zucchini

This hybrid zucchini variety produces very dark green fruit in as few as 48 days from planting. The plant is a compact bush.

'Gold Rush' Zucchini

'Gold Rush' is a hybrid zucchini with golden yellow, smooth, straight fruits. The compact plants have an open habit which makes harvesting easy. 45 days to maturity

Garden Plans for Summer Squash

Easy Children’s Vegetable Garden

This easy children's vegetable garden plan will please gardeners of all ages. In addition to unusual and fun-looking vegetables, including 'Scallop' summer squash, the plan includes a playhouse made of bean vines to create welcome shade. Kids will also love making the garden pretty with the marigolds that flank the bed's edge. If you aren't able to find the exact cultivars listed, substitute with others that have similar colors, shapes, and sizes. 

French Kitchen Garden Plan

This French-style kitchen garden plan reflects the aesthetic of kitchen gardens in medieval France with a central diamond-shaped bed and four larger raised beds, with wide brick pathways running between them. A row of ornamental perennials or shrubs is intended to serve as a hedge around the perimeter, set off by a white picket fence.