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Squash is part of the cucurbit family (Cucurbitaceae). Winter squash includes acorn, butternut, buttercup, and Hubbard, while summer squash includes yellow squash, zucchini, and bush scallops. Both groups are warm-season vegetables and are easy to grow in well-drained, fertile soil.
I will cover growing each seasonal crop separately.
How to Grow Winter Squash
Introducing Winter Squash
If you have the space, growing winter squash is simple. There is an astounding diversity in fruit size, shape, and color available in variations in addition to the traditional butternut and acorn squash. If you have limited room, pick a bush variety.
Winter squash (Cucurbita moschata) is a warm-season crop that is relatively easy to grow but requires a longer growing season. Most varieties need 85 to 120 days from sowing to maturity and should be seeded in situ after all danger of frost has passed.
Soil temperatures should be between 70 and 90 °F (21 and 32 °C) for optimal germination. Soil should drain well, be rich in organic matter, and have a pH of between 6.0 to 6.6 for a healthy harvest.
Winter Squash Varieties
Whether Cucurbita pepo (the same species as summer squash), C. moschata, or C. maxima, most varieties of winter squash produce sprawling vines, so if your growing area is limited, grow bush or semi-bush varieties.
Winter squash comes in an astonishing array of sizes, shapes, and colors. Avoid varieties that require a long growing season (100 or more days) if your season is short.
Popular varieties include:
- Butternut
- Acorn
- Buttercup
- Hubbard
- Delicata
- Gold Nugget
- Harlequin
- Vegetable Spaghetti
- Sweet Dumpling
Soil Preparation for Squash
Prepare your beds a couple of months before planting by adding about 4 inches of compost; you don’t need to work it in. Early inclusion also allows weeds to germinate, enabling their removal before planting your crop. When planting, don’t till the bed to prevent harming the established soil biota.
If you use hills, go ahead and create them, adding compost two months before planting. Hills should be about 12 inches (30 cm) across and four inches (10 cm) high.
Planting Winter Squash
Soil temperatures should be between 70 and 90 °F (21 and 32 °C) for optimal germination. Soil should drain well, be rich in organic matter, and have a pH of between 6.0 to 6.6 for a healthy harvest.
All squashes are propagated sexually by seeds. Seeds will not germinate if your soil is colder than 59 °F (15 °C). Plant your butternut no earlier than two weeks after the last frost. You can plant winter squash up to 12 weeks before your expected first frost date.
Plant seed just under an inch deep and a couple of inches apart. Each hill will eventually only have a single plant, the weaker ones having been culled as they reach about two inches in height. Winter squash needs between 6 to 8 hours of direct sunlight a day.
Plants should germinate within ten days but may take less than a week if soil temperatures exceed 77 °F (25 °C).
Squash are particularly susceptible to frost and prefer warm soil. Therefore, don’t rush to plant in the early spring. Wait two weeks after the last frost date, and the soil has warmed to roughly 70 °F (21 °C).
There is no reason to start winter squash indoors unless you attempt to produce a long-season variety in a region with early frosts. Instead, direct seed into rows or hills heated and drained earlier in the season.
Seeds in beds should be sown in rows 6 to 12 inches apart and 4 to 8 feet apart. To thin them out, trim them to one plant every 18 to 36 inches.
If you need an early start, plant indoors in 2 to 3-inch pots or cells for three to four weeks before transferring them outside.
Before transplanting, acclimatize plants by slowly introducing them to outside temperatures and reducing water applications. After all threat of frost has passed, plant transplants in the garden at the final spacings mentioned.
Caring for Winter Squash
Butternut squash is a heavy feeder; you will need to add some nitrogen to boost your crop yield. Once your plant has reached a reasonable size, stop fertilizing to trigger flower formation. You can boost nutrition once the pods have formed, but avoid overdoing it.
Irrigate the squash plant on the base, as wetting the foliage benefits disease-carrying bacteria. A thorough soaking followed by an opportunity for the roots to dry out and get some air is the best approach for all plants.
Check the soil with a moisture meter or your finger and water once the top couple of inches has dried. It is best to water early in the morning to allow your plant leaves and flowers to dry.
Blossom rot is generally caused by a calcium deficiency linked to water availability. While overwatering cause root rot, underwatering causes end rot, so keeping the soil moist but not wet should be your aim.
Growth can be accelerated by black plastic mulch, particularly in chilly, short-season climates. To lessen mildew, remove or till in vines after the growing season. Use row covers to protect plants early in the season and stop insect issues. Remove when it’s hot outside or before it blooms to facilitate insect pollination.
Mulching plants aids in moisture retention and weed control. Squash borers won’t deposit eggs if you pile soil up around the base of the plants.
How to Grow Summer Squash
Introducing Summer Squash
Summer squash comes in a variety of shapes and colors. Bush varieties take up relatively little space, and if you consistently remove ripe fruits, the plant will keep producing up to frost.
The Cucurbita pepo species is common to summer and winter squash. Spreading vine Cucurbita pepo, often called acorn squash, has yellow fruit-bearing blossoms. The mildly flavored fruits can be fried, baked, mixed with pasta, used in soups, and more.
Acorn squash is native to North America and is a vigorous plant that needs fairly wet soil and more than six hours of sunlight daily. Add compost to the soil around the squash in the late fall to promote growth and mulch the squash to improve water retention and weed control.
Although it thrives in vegetable gardens, on trellises, and as a cover for exposed soil, acorn squash is ideally suited for expansive landscapes. It is simple to plant from seed, especially in warm soils. Plant winter squash after the final frost, from late spring to early summer.
The fruit is a berry called a pepo that has a hard rind. Fruits may be long or round, large or small, smooth or warty. Some varieties have edible flesh, while some are too hard or bland to eat, though all seeds are edible. Cucurbita pepo has a more rigid, thicker stem than other Cucurbita species.
Planting Summer Squash
Summer squash seeds germinate when soil temperatures reach 60 to 105 °F (~15 to 40°C). Ideally, seeds should not be planted before soil temperatures reach 70 °F (21 °C). Optimal germination temperatures are in the region of 95 °F (35 °C).
Caring for Summer Squash
Squash are particularly susceptible to frost and prefer warm soil. Therefore, don’t rush to plant in the early spring. Wait two weeks after the last frost date, and the soil has warmed to roughly 70 °F (21 °C).
There is no reason to start summer squash indoors unless you attempt to produce a long-season variety in a region with early frosts. Instead, direct seed into rows or hills heated and drained earlier in the season, sowing 4 to 5 seeds per hill.
Hills should be spaced 4 to 8 feet apart, informed by fruit size. Cull weaker plants by cutting them off at ground level, thinning the hill to about three plants – don’t pull them out as you may damage adjacent plant roots.
Seeds should be sown in rows 6 to 12 inches apart and 4 to 8 feet apart. To thin them out, trim them to one plant every 18 to 36 inches.
If you need an early start, plant indoors in 2 to 3-inch pots or cells for three to four weeks before transferring them outside.
Before transplanting, acclimatize plants by slowly introducing them to outside temperatures and reducing water applications. After all threat of frost has passed, plant transplants in the garden at the final spacings mentioned.
Growth can be accelerated by black plastic mulch, particularly in chilly, short-season climates. To lessen mildew, remove or till in vines after the growing season. Use row covers to protect plants early in the season and stop insect issues. Remove when it’s hot outside or before it blooms to facilitate insect pollination.
Mulching plants aids in moisture retention and weed control. Squash borers won’t deposit eggs if you pile soil up around the base of the plants.
Frequently Asked Questions
Why are my squash flowers not forming fruit?
Squash (both summer and winter) is a monoecious plant, forming separate male and female flowers on the same plant. Ambient temperatures are known to affect gender expression in cucurbits. Cool conditions, especially on nights, favor female flower formation, so they emerge first. In the absence of male flowers (warmer conditions), there is poor pollination and a low fruit set. Typically, female flowers appear a week or two before male blossoms. Stagger seed planting by ten days to ensure both genders are available simultaneously for optimum pollination.
When should I harvest my squash?
Harvest the squash when each fruit is large enough to eat, and don’t allow them to get large and old. If you harvest regularly, the plant will produce new flowers and continue to grow young squash. Fruit production is motivated by posterity, so allowing all the fruit to mature before harvesting stops fruit initiation. If the fruit is constantly removed from the plant, production will continue.
Why are some of my squash’s ends rotting? What can I do to prevent this from happening?
Blossom end rot is common in early-forming squash, tomato, or pepper plants. The fruits that follow should be fine. The disease is linked to a calcium deficiency usually caused by erratic water uptake. Consistency is key in keeping the soil evenly moist, not too wet or dry. A fertilizer that includes calcium and magnesium will help, so apply some Epsom salts (magnesium sulfate) occasionally by mixing a spoon full with a gallon of water.
Why has my squash plant stopped flowering?
Flowering stops when temperatures exceed 90 ⁰F (32⁰C) and may recommence when temperatures drop into the 80s (<30 ⁰C). If you allow fruits to remain on the plant for too long (beyond ripeness) before harvesting, the plants may not bear fruit again–they believe they have produced seed and will now wait to die when the frost comes.
How do I know if I’m overwatering?
Squash soil should be evenly moist, not wet or dry. It’s best to water plants deeply and allow the soil to dry before watering again, but consistency is vital. Don’t allow the soil to be dry for extended periods. If your plants are in containers, you may want to get a moisture meter to see how moist the soil is at 4 inches deep (you can also use the meter outdoors).
Can I grow potato and squash plants together?
Squash requires more water than potatoes, so if the soil is not well drained, your potatoes might suffer from the abundance of water you give your squash. Plant both in raised wide beds or mounds; you should have no problems planting them relatively close. Growing each in separate beds would be optimal. Potato flowers do not need to be pollinated to produce potatoes, and there is no need to worry about cross-pollination.
Potatoes can be spaced as close as 12 inches apart in rows; allow 3 feet between rows. Give them a bit more room in a wide or intensively planted bed. Summer squash is best planted 2 to 3 feet apart. Assuming your soil is well drained, give your squash enough room to spread and grow your potatoes as close to the squash as you like.
In Closing
The term squash comes from a Native-American word that describes an edible gourd, i.e., a hard fleshy fruit with hard skin. There are hundreds of hybrids to choose from that provide diverse characteristics and resilience traits, and knowing their preferences, quirks, and uniqueness allows you to better care for them.