How to Grow Squash

Squash is a prolific producer of large fruits which are rich in carbohydrates and dietary fiber. In a Three Sisters garden system, its wide leaves and sprawling vines provide excellent water retention and weed suppression for the entire garden. If growing conditions are optimal, squash can be one of the most hands-off and productive crops in the garden.

Types of Squash

Squash varieties are typically broken into two categories: summer squash and winter squash. Summer squash includes varieties like yellow crookneck, zucchini, and koosa which are meant to be picked and eaten when the fruit is still tender. Because these varieties are traditionally picked in their unripe form, they have not yet developed a protective skin which gives them a relatively short shelf-life.

Winter squash includes varieties like butternut, acorn, and delicata. These varieties are harvested after they reach full maturity and develop a thick outer skin to protect the flesh and seeds. The name “winter squash” is somewhat of a misnomer and it leads some new gardeners to believe that it can be grown in the winter. The name actually describes the ability of winter squash to store at room temperature for long periods of time so it can be eaten throughout the winter.

Growing Conditions

As anyone who has discovered a volunteer squash exploding out of their compost pile can tell you, squash loves organic matter. If your soil is lacking in organic matter, consider adding compost to the section where you plan to grow your squash. Squash needs full sun (at least 6 hours per day) and about an inch of rain per week to grow optimally. Squash can be direct-seeded or transplanted into the garden after the average last frost date in your growing zone.

Summer squash typically grows in a “bushing” habit so it will stay within a 2 or 3 foot area of where you plant it. This means that you can plant your summer squash about 2 to 3 feet apart without worrying about the plants competing for sunlight and nutrients. Winter squash, on the other hand, will sprawl far and wide with vines that sometimes reach up to 20 feet in length. You can train the winter squash vines as they grow so just make sure you have enough of an area around each plant to snake them around. We like to allow winter squash vines to run down the pathways of our gardens to turn otherwise unused space into productive areas in the fall.

All squash is dioecious, meaning its male and female reproductive organs are found on separate flowers. For this reason it cannot be grown without pollinators unless you are growing a specialized greenhouse variety labeled “parthenocarpic." If your garden is lacking in pollinating insects you can hand-pollinate the squash by collecting pollen from a male flower on a cuetip or paintbrush and transporting it to the female flower which is distinguished from the males by having a small squash embryo at the base of its flower. For a long-term solution to poor pollination, consider planting a pollinator garden to attract native insects and save yourself some work.

Pests and Diseases

The two primary pests that you will battle in your squash patch are the aptly named “squash bug” and “squash vine borer.” Squash bugs are sapsucking insects that typically lay their eggs on the underside of squash leaves so their larvae can feed on the plants as they develop. Both the adults and larvae suck sap from the leaves and stems which can be detrimental and even kill the plant if their numbers are large enough. Squash bug populations can be controlled from year to year by removing and composting all squash debris from your garden at the end of the season. Squash bugs overwinter in this garden debris so removing it resets their population each year. You can also check your plants periodically and scrape any unhatched eggs off of the leaves with your fingernail.

Squash vine borers are orange and black moths who lay their eggs at the base of squash plants so their larvae can tunnel in and eat the vine from the inside out. Their boring often results in a substance that looks like sawdust spilling out of your squash vines and if you find this early you can actually perform a little bit of field surgery to remove the grubs from the hollow vines. Just make sure to cover the incision with soil or gardeners tape after you remove the larvae.

The most effective method of keeping both of these insects off of your plants is to cover them with row cover or insect netting when they are still young. Unfortunately because squash needs to be pollinated by insects, you will have to remove the cover as soon as your plants start flowering to allow pollinators in.

The most common diseases to appear on squash plants are powdery mildew and blossom end rot. Powdery mildew appears as a white blotchy substance that coats the leaves and eventually causes the plant to wilt and die. If you live in an area with high humidity and frequent rainfall you will most likely experience powdery mildew at some point in the season. Luckily many varieties of squash are resistant to this disease which will buy you a lot of time before your plant succumbs to the blight. Look for varieties that say “Powdery Mildew Resistant” or “PM Resistant” when selecting your seeds.

Blossom end rot is exactly what it sounds like, the blossom end of your squashes will develop a black spot and eventually rot the whole fruit. This is often caused by calcium deficiency or lack of water so if you are seeing blossom end rot, make sure you are watering consistently and consider adding calcium to your soil for help with this problem in the long-term.

Harvest and Use

Harvesting squash is one of the most rewarding garden activities and often results in an armful of food picked in minutes. Because summer squash is harvested in its unripe form, it’s up to your discretion when you pick it. You can even eat the flower before the fruit is fully formed. For most varieties the optimal time for tenderness and size is about 6 to 8 inches. Because summer squash is such a prolific producer you will likely need to harvest it every few days at the peak of the season. If you ignore your summer squash for a week you might discover some giant, overgrown fruits. If this happens, you should look up a good zucchini bread recipe because they will not be very good on the grill.

Winter squash is one of my favorite crops to harvest. Because it's harvested as a fully mature fruit with a protective outer skin you can simply leave the crop in the garden until the plant starts to die back. Then you get to do the gardener’s version of an egg hunt and walk around plucking the delicious gourds. In my experience, there are always more than you thought, so look carefully. The best way to tell if a winter squash is fully mature is to feel the stem at the top of the fruit. If the stem feels hard and woody, it's mature. Cut the stem several inches above the fruit when harvesting so it can properly seal and cure. Hard freezes can damage winter squash fruits so make sure to harvest them all if you are seeing lows below 32°F in the forecast. Often even the immature fruits will mature and cure properly if harvested and brought indoors so don’t let those go to waste.

Squash is one of the most rewarding crops to grow and provides a bounty of homegrown vegetables with very little effort. If you’re looking to round out your Three Sisters garden or provide a pile of veggies for your summer cookout, you can’t go wrong with squash.