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How to Grow Squash: Planting, Growing, Harvesting

How to Grow Squash: Planting, Growing, Harvesting

Squash is one of the first vegetables that come to mind when you think of an abundant harvest. From summer varieties such as Bottleneck and yellow zucchini, to winter classics such as pumpkin and Butternut, squash is a productive vine that will keep you harvesting from early summer until late fall.

However, growing squash in your vegetable garden takes a bit of know-how, especially if you’re a beginner gardener.

In this growing guide, we’ll take a look at how to grow squash from seed, starting with preparing the planting site, watering, pollinating, and managing common pests and diseases. We’ll also discuss the subtle differences between growing summer and winter squash, and take a look at the best way to grow this wonderful vegetable in containers.

Squash Varieties You Can Grow

There are two types of squash plant you can grow in your garden: summer and winter. The main difference between them is the way they are harvested and stored, but they also have slightly different growing habits.

Let’s take a closer look at each squash variety.

Summer squash

As the name suggests, summer squashes are harvested in summer or early fall. They have a tender, edible rind, and are best picked before they fully mature. Summer squash plants are climbers and can reach a height of up to 7 feet (2.1 meters).

Most summer squashes are varieties of the Cucurbita pepo plant, but this category also includes some interesting Asian varieties. Here are some you can try growing:

Winter Squash

Winter squashes come in many shapes and sizes, but they all have two things in common. They have a vining or sprawling growth habit and are harvested in late fall or early winter, when they’re fully mature. Unlike summer squashes, they have a thick rind, which protects them from pests, and allows them to keep in storage for 2 to 3 months.

Pumpkins are by far the best-known variety of winter squash. Other popular species and cultivars include:

All squash varieties have similar growing requirements. You can use this care guide to grow any of the varieties listed above, from pumpkins to zucchini plants, and even ornamental gourds.

flowing marrow with fruits

When Is the Best Time to Plant Squash?

Squash is a summer crop that grows best in warm climates. This vegetable needs temperatures of at least 60°F (15.5°C) for the seeds to germinate and the plants to produce an abundant harvest. It also requires a minimum of 60 frost-free days to reach maturity. This can make growing squash a bit of a challenge, especially in areas with a short growing season.

You can plant summer squash outdoors, in the garden soil, in early summer. Depending on the variety, it can mature in as little as 50 days, so it’s better suited for shorter seasons. Winter squashes, on the other hand, take up to 100 days to mature. In this case, it’s best to start them from seed indoors in spring, 5 to 6 weeks before the last frost date, then transplant them when the soil temperature is at 70°F (21°C).

For best results, check out our planting calendar before you start sowing your squash seeds. This will give you a better idea about which planting month works best in your hardiness zone, and allow you to make the most of your growing season.

Where Should You Plant Squash?

Squash needs full sun to thrive. Always plant it in a part of your garden that receives a minimum of 6 hours of sunlight per day. Full sun will help the plants grow faster and produce a bumper crop, and also prevent fungal diseases such as powdery mildew.

For growing winter squash, make sure to pick a large planting site. Mature plants need lots of space for their vines, large leaves, and fruit. A single plant can easily take up at least 50 sq ft (about 5m²) of your garden. If you’re in a pinch for space, try to grow summer squash instead, which can be grown on trellises.

How to Plant and Grow Squash

Growing squash plants is easy if you provide them with these three things: full sun, consistent watering, and all the organic material you can get your hands on. They are a great fit for garden soil, raised beds, and even containers, but in cooler climates, they will grow best in a greenhouse.

Here’s what you need to know about growing summer and winter squash in your own garden.

Prepare the Soil

Squash grows best in loamy, moist, well-draining, slightly acidic soil that contains plenty of rich organic matter. Never underestimate how much compost squash plants need. Realistically speaking, the best place to grow squashes is in your compost heap. Of course, that’s not always feasible, so for best results, try to add as much organic material into the soil as you can before you start planting.

Dig up the soil to a depth of one foot (30 cm) and work in plenty of compost, well-rotted manure, and leaf mold. Your aim is to create a moisture-retentive yet well drained soil. If your garden has clay-heavy soil, adding straw, bark, wood chips, and some pea gravel will help.

After digging and amending the soil in spring, cover it with a thick, black plastic tarp. This will smother out any stubborn weed seeds that might germinate. Most importantly, though, it will help warm up the soil, which means you can start planting squash sooner.

Sow Squash Seeds

There are two things to keep in mind before you start sowing squash seeds:

  1. Seeds need plenty of warmth to germinate.
  2. Squash seedlings have delicate roots and don’t transplant well.

Ideally, you should sow squash seeds directly into the ground, but that may not be an option in all gardens and growing zones. So let’s take a look at what you need to do to sow seeds successfully.

For direct planting in the garden soil, wait until late spring or early summer, or when the soil temperature reaches 70°F (21°C). There’s no need to soak the seeds in advance. Simply make a mound or hill and plant 3 to 4 seeds in each mound, about 1 inch deep (2.5 cm), then water them well.

If you live in an area with short summers, and if you’re planning to grow winter squash, the best option is to plant seeds indoors about 5 or 6 weeks before the last frost. To avoid damaging the seedlings, use compostable peat pots at least 3 inches wide (7.5 cm).

Fill each peat pot with a well-draining, nutrient-rich potting mix. Plant one seed per pot, ½ an inch deep (about 1 cm), and water it well. Keep the pots on a sunny windowsill, but away from cold drafts. You can also use a seedling heat mat to speed up the process.

Squash seeds germinate in about 7 to 10 days. They are very sensitive to drought, so water them regularly, but don’t drown them.

Organic Zucchini Homegrown

Transplanting and Spacing

You can transplant squash seedlings outdoors when they have at least two true leaves and when soil temperatures reach 70°F (21°C). Dig a hole the size of the compostable peat pot, and place the pot directly in the ground, without removing the seedling first. Water your transplants thoroughly, and add a layer of organic mulch around the plants to help preserve moisture.

The spacing for squash plants depends on which variety you’re growing. For summer squash and zucchini, keep 2 to 3 plants per hill, at least 3 feet apart (90 cm). For winter squash, plant 2 plants per hill, and keep the hills and rows at least 4 feet apart (1.2 meters).

Water

Squash is deathly sensitive to droughts and you’ll need to water it deeply and regularly. Once a week is ideal, but always check the soil with your finger to avoid overwatering.

Using a drip irrigation system is the best way to water your squash plants. This ensures that they receive the right amount of moisture, and also avoids overhead watering, which can result in fungal diseases.

Fertilizers

Squash plants are very heavy feeders. They need plenty of compost before sowing, and regular fertilizer applications once they start flowering.

If you’ve added compost and manure to your soil before planting, you don’t need to fertilize your squash plants until they start flowering. Otherwise, add some organic, slow-release fertilizer such as bone meal and liquid seaweed soon after planting or transplanting.

When the squash plants begin to bloom, use a balanced organic fertilizer to give them a nutrient boost. Check the instructions on the label and repeat the fertilizer applications accordingly. Always water your plants well after using fertilizers, to prevent burning the roots.

Supports

Squashes are vining plants that love to climb and sprawl across your garden. They don’t always need supports but will benefit from them, to help with air circulation and keeping fruit off the ground.

For summer squash, the easiest type of support is a tripod or plant teepee made out of plastic or bamboo canes. Use soft twine to tie the squash vines when they’re young. As they mature, the plants will use tendrils to climb on their own.

For winter squash, especially varieties that produce large, heavy fruit, using supports isn’t always necessary. The fruit has a thick, tough rind, which makes it more resistant to hungry pests. If you want, use a trellis with a sturdy frame to make sure that it doesn’t fall over under the weight of the fruit. Or simply put a piece of plastic, wood, or slate under each fruit, to prevent it from sitting directly on the ground.

Pollinating Squash Plants

Manual pollination is not mandatory for squash plants. But it’s the best way to encourage fruit production and ensure that all your hard work results in an abundant harvest.

Start by identifying the male and female flowers. Male flowers have long, thin stems, and bloom a few days before the female ones. Female flowers have a small lump on the stem, which becomes the squash fruit after pollination. To manually pollinate your squash, pick a male flower, then rub it against a female flower to transfer the pollen.

One of the best parts about manually pollinating squash plants is the fact that you can eat the male squash blossoms when you’re done. Dip them in batter and fry them, stuff them with cream cheese and bake them, or just eat them raw. Whichever method you use, they’re guaranteed to be a tasty summer treat.

When and How to Harvest Squash

Most summer squash varieties take around 60 days after sowing to reach maturity. As a rule of thumb, you can start harvesting summer squash and zucchini when the fruit is between 6 and 8 inches long (15 to 20 cm). Don’t leave them on the vine for too long, or they will become bland and develop a thick rind. Zucchini left on the vine for too long will turn into bland, seedy marrow.

After harvesting, keep summer squash in the crisper drawer of your fridge for 7 to 10 days. Summer squashes have a short shelf life and are always best enjoyed fresh. If you have a bumper crop, blanch it and freeze it for 3 to 6 months.

Winter squash grow at a slower rate and can take anywhere between 90 and 120 days to reach maturity. Harvest winter squash in early to mid-fall, when the plants begin to dry out. Test each fruit with your fingernail: if you can leave a mark on it, the rind is still too soft, and the fruit needs longer to ripen. Mature squash fruit can tolerate a mild frost, so you can leave them in the garden until late fall.

Always use a sharp pair of gardening scissors to harvest your squash, regardless of variety. The plant stem can break easily, so avoid pulling the fruit by hand. If you’re harvesting winter squash, always leave a 2-inch (5 cm) stalk on each plant.

Storing and Ripening Winter Squash

Unlike summer squash, which can be eaten and stored immediately after harvesting, winter squash needs to be cured and ripened first. This allows the starches to convert into sugar, giving winter squash its iconic sweet aroma, and also helps harden the skin, which protects the fruit from spoiling.

After harvesting winter squash, keep it in a warm, dry, and well-ventilated room for 2 weeks. Then, move it into a dark, dry place, with temperatures around 50°F (10°C). One of the best ways to store this fruit is in a net or mesh bag, hanging from an S-hook. If the stalk is intact and the rind is unblemished, winter squash can last for up to 3 months.

Common Squash Problems

Squash plants can be susceptible to a wide range of pests and diseases, from viral and fungal infections to aphids and squash bugs.

Common squash pests include cucumber beetles, squash vine borers, slugs and snails, aphids, stinkbugs, and squash bugs. Most pests will target the squash leaves and fruit, and they’re easy to handle by using row covers for young plants and using an insecticidal soap solution. The tricky ones are squash borers. The vine borer eats the stem from the inside, so pesticides won’t have much effect on it. Trim infested vines and burn them, and practice crop rotation to avoid a buildup of pests.

Common squash diseases include powdery mildew and mosaic virus. Powdery mildew appears in hot, humid weather, and usually infects crowded plants. You can prevent it by avoiding overhead watering and leaving at least 3 feet (90 cm) between the plants to provide good air circulation. Mosaic virus, unfortunately, has no cure, and it’s easily transmitted through infected seed and plant debris. If you find it in your garden, remove all the vines and infected plants immediately and burn them.

Squash can be susceptible to blossom end rot, a condition caused by a lack of calcium. This condition is often made worse in very acidic soils, if the plants are experiencing drought, or if you’re using too much nitrogen-rich fertilizer. Keep your plants well-watered, use a balanced, organic fertilizer, and treat your soil with limestone if the pH is below 5.5.

Companion Planting With Squash

The best plants to grow with squash are corn and beans. Native Americans called them The Three Sisters and often planted them together with great success. The large squash leaves help suppress weeds and keep the soil moist, corn acts as a natural support for beans, and beans fix nitrogen into the soil, for all plants to enjoy.

You can also plant squash as a follow-up crop to early spring vegetables such as radishes, lettuce, and spinach, which will be harvested before you sow the squash seeds. Planting dill, marigolds, cosmos, yarrow, and nasturtiums is a great way to attract pollinators and beneficial insects such as ladybugs and lacewings.

Squash and cucumber have many pests and diseases in common, and should never be planted together.

Hand harvest butternut squash

How to Grow Squash in Containers

Growing squash in containers is a great way to save space and make the most of a short growing season. If you live in an area that gets less than 60 days of hot, sunny weather, you can sow seeds indoors, then simply move the pots to the garden once the weather gets warm enough. This way, you’ll also reduce the risk of damaging the seedlings during transplanting.

Use a large, 24 inches wide container with drainage holes at the bottom, and fill it with a nutrient-rich, well-draining soil mix. Plant 2 seeds per pot, about ½ an inch deep. Water them well, and keep the container in a warm, bright room. Give your plants a balanced organic fertilizer when they begin to flower and remember to manually pollinate them.

Growing Squash Indoors

You can grow squash indoors if you have a sunny balcony or a room with southern exposure. Growing winter squash, such as pumpkins, is possible, but not ideal. These plants take up a lot of space and need plenty of sunlight to reach their full potential.

For best results, try growing summer squash or zucchini, or bush-type varieties that are suited for container growth. Popular cultivars for indoor pots include Jack Be Lite, Bumpkin, Bush Acorn, Pattypan, Early Summer, and Round Zucchini.

Squash is a demanding crop even for seasoned gardeners. It will use up most of your garden’s resources, starting with compost and the sunniest spot it can find. It needs lots of water, babysitting to encourage fruit production, and will attract a host of pests and diseases.

However, it is one of the most rewarding vegetables you can grow. Come harvest time, you’ll understand why all the hard work was needed. And with this grow guide, you’ll become an expert at growing squash at home, and look forward to planting it again and again.

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