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Growing Summer Squash

    For many, growing and harvesting yellow and zucchini squash epitomizes summer. Winter’s short days and cold weather have many longing for the garden. While the memory of cutting off those tender yellow squash may intensify that longing, it helps to remember spring planting is just around the corner. 

    The word “squash” comes from the Massachuset Indian word askutasquash, meaning “eaten raw or uncooked.” While we usually enjoy our squash cooked, summer squash is easily enjoyed raw. The tenderness of summer squash is attributable to being harvested when immature. If left to mature, it would develop a hard rind that is not usually edible. Many gardeners have experienced this, when a green zucchini evades detection and grows into a huge fruit in just a few days. Winter squash is, in fact, left on the vine to develop a hard skin that increases its ability to maintain freshness when stored for months. 

    Summer squash (Cucurbita pepo) is usually one of the easiest and most prolific crops to grow. The 3 main types of summer squash include yellow, both straight neck and crookneck; green, gray or yellow zucchini; and white patty pan, saucer-shaped or scalloped. There are many varieties and cultivars having different fruit shapes and colors, and some cultivars are more disease-resistant.  NC State Ext/Basics for Growing Squash.

    According to Virginia Tech’s Vegetable Planting Guide, you can plant squash in your garden after the last spring frost date. Depending on where you live in Virginia, that could be any time between April 15th and May 15th. Albemarle County’s hardiness zone was recently changed from 7a to 7b, and the last spring frost date is now estimated to be between April 5th and April 15th. 

    However, squash grows best if the temperature is at least 65°-70°F. This is one of the reasons that squash is usually planted in “hills.”Not only does this help to warm the soil, it also promotes good drainage. Plant 3-4 seeds per hill, and leave 3’-4’ between hills. If you plant in rows, leave several feet between plants and 4’-5’ feet between rows. Although summer squash is not vining, the plants become very large. Many stems will come in contact with the soil and develop roots to help provide water and nutrients to the plant. 

    Squash is easily directly sown in the garden, but if you decide to grow transplants, start your plants indoors 3 weeks before your last frost date. Use a soilless seed starting mix and transplant into the garden when they have developed their first true leaves (the leaves that develop after the cotyledons or seed leaves.) Keep them in a warm, sunny window.  A heating pad and grow lights can be used if you do not have an ideal location.

    Placing a gentle fan on the young seedlings will help them develop strong, resilient stems. You’ll need to “harden off” the plants before transplanting them to your garden. To do this, place the plants outdoors for an hour on the first day and increase the time outside until they have acclimated. You may need to shelter them from direct sunlight, depending on the temperature and how they tolerate the outdoors. Give them a week to adapt, before moving them to your garden. Be sure to incorporate some compost into your soil before planting. 

    squash plant
    Photo: Gena Breakiron

    Your squash plants will need at least 6 hours of sun a day, but they prefer 8-10 hours. Additionally, squash will require at least 1 inch of water each week. Try to water regularly, in the morning, and keep the stream at the base of the plant. If the weather is particularly hot and dry, as we often experience in central Virginia summers, your plants will need additional water to continue to produce fruit. 

    When harvesting your squash, be sure to cut the stem to avoid damaging the plant. The more you harvest the immature fruits, the more fruit your plant will produce. Naturally, plants want to produce seeds and offspring, so once mature seeds are produced, the plant will decrease production. 

    Unfortunately, squash plants, like many garden plants, can fall victim to a host of diseases and pests. They can be difficult to manage and continue to maintain an organic garden. Below are some methods for battling two of the most troublesome: the squash vine borer (Melittia cucurbitae) and the squash bug (Anasa tristis). You can read about other pests and diseases by visiting the links provided at the end of this article. 

    Additionally, If you want a longer harvest window, you may want to plant fewer plants at first, and then plant again every two or three weeks. Eventually, your successive plantings will outlast the insect pests. 

    Both the squash vine borer and the squash bug overwinter, vine borers as a pupa or pupa in cocoon 2” under the soil, and squash bugs as adults under plant debris, rocks, compost, or anything else they can find for shelter. Gardeners may be able to avoid these pests by planting later in the season and thereby missing the insect’s life cycle. 

    To prevent the vine borer moth from laying its eggs on the stem, try wrapping the stems with aluminum foil. If the vine borer is already present, use a sharp blade to cut halfway through the stem of the plant and extract and destroy the larva. Then, mound the soil up around the wound so it can heal.

    The squash bug is a bit more difficult to deal with, but they won’t kill your plants as quickly as the vine borer. However, once the bugs become established, your plants will decline quickly. Again, consider planting later in the season. In our area, gardeners can plant in mid- to late June and possibly experience fewer or no squash bugs. They will still have an abundant harvest and enough time to plant successive crops through mid- or late August, with harvests likely into October. Look for pictures and a great article on the squash bug at the link as the end of this article.

    Low tunnel
    Low tunnel protects plants while tender. Photo: Gena Breakiron

    If you choose to plant early and take on the squash bugs, there are some ways to combat them. First, row covers or a low tunnel could be used until the flowers develop fully. You’ll want to wait until you have plenty of male and female flowers. The male flowers will develop first, and there may be quite a few before the first female flowers bloom. You’ll know the difference because the male flowers will be upright, whereas the female flowers will be oriented almost parallel to the soil. This helps the fruit develop horizontally without snapping off as it becomes heavy. Once you have a few female flowers, you’ll want to remove the row covers so natural pollination can occur.

    Whether you use row covers or not, you’ll want to be diligent about looking for eggs on the leaves. They will likely be on the undersides of the leaves, but some will also be on the surface. You can remove them by tearing off the piece of the leaf that has the eggs (they are too hard to crush), or you can try using some strong tape to pull them off. This may damage your leaves at times, but it will not be as much damage as the bugs can manage if left on the plants. Be sure to put the used tape in a plastic bag and dispose of it in the trash. 

    Squash bugs also like to hide under things, especially at night. You will notice them congregating under leaves that are on the ground. Because of this habit, you can lay boards or cardboard under the plants. Lift the boards early in the morning, and squish as many bugs as you can. Make regular inspections of your plants, and you may be able to keep up with them long enough to harvest a good amount of squash. 

    I have found I can smash many squash bugs if I wet the plants with a gentle spray of water during the heat of the day. The water appears to cause the bugs to come to the surface of the leaves, most likely in survival mode. They are more easily crushed when they come out from hiding.  Conducting this procedure in the middle of the day, allows the plants to dry before the cooler temperatures of the night, thus avoiding mildew.  

    When the squash bugs have become too numerous, or your plants begin to decline, it may be time to remove them. Pull the plant out of the ground and place it in a large black plastic trash bag. Look for squash bugs on the ground that will have fallen from the plant and dispatch them or add them to the bag. Twist the top of the bag firmly, so no bugs escape. Leave it in the sun for a few days, and dispose of it in the trash. Never put diseased or pest-infested plant matter in your compost! 

    Most gardeners feel a summer vegetable patch is not complete without summer squash. While these plants are not without their troubles, they can prove to be worth the effort. Online, you’ll find an abundance of recipe ideas. When you find your kitchen inundated with squash, don’t forget you can always share with your neighbors or a food pantry. 

     

    Featured Photo:  Gena Breakiron

    SOURCES:

    Virginia’s Home Garden Vegetable Planting Guide: Recommended Planting Dates and Amounts to Plant (note that this publication has not yet been updated to reflect the change in hardiness zones which occurred in the autumn of 2023)

    Cucumbers, Melons, and Squash/VA Tech Pub. No. 426-406

    Squash Bug in Virginia Home Gardens/VA Tech

    Growing Summer Squash (Zucchini) in a Home Garden/University of Maryland Extension

    Squash Vine Borer/VA Tech

    Easy Gardening: Squash/Aggie Horticulture/Texas A & M

    Squash Bug in Virginia Home Gardens/www.pubs.ext.vt.edu/ENTO/ento-578/ento-578

     

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