How to Grow Squash in Raised Beds: 9 Pro Tips

When you hear tales of gardeners dropping off bags of zucchini on their neighbors’ porches, it’s easy to assume squash plants are easy to grow. And in the right conditions, they are! However, they are susceptible to diseases, pests, drought, and other issues that can make growing them challenging.

Whether you’re hoping to grow enough zucchini to stock your freezer for the winter or want to grow an heirloom pumpkin that you can’t find in stores, knowing a few tips will make your growing endeavors easier. I’m going to share some helpful tips I’ve learned about plant spacing, disease prevention, pest control, and more.

Know the Differences Between Winter and Summer Squashes

When people talk about squash, they’re generally talking about one of two major categories of plants: summer and winter. These two types vary in growth habit, fruit production, and harvest time. Learning which type you’re growing will help you learn how to best plant and care for your plant.

Gardeners harvest tender summer squash a few days after the fruits form. While you can harvest larger fruits, these tend to be rough and seedy. Healthy plants continue producing new flowers and fruits for at least a month. Zucchini, pattypan, and yellow crookneck squash are all types of summer squash. 

Winter squash are ready to harvest when their fruits are fully mature. At this point, they have tough skin, fully developed seeds, and starchy flesh. Winter fruits take a longer time to maturity than summer types, and all their fruits are ready to harvest around the same time. They also often require a curing process for storage. Butternut, acorn, spaghetti, kabocha, delicata, and kuri are all types of winter squash.

Take Note of Bush and Trailing Varieties

Once you’ve determined whether you want to grow winter or summer squash, it’s time to look at the plant’s growth habits. Squash plants can grow in a compact bush form, a trailing form, or an in-between semi-bush form. As you probably expect, trailing forms take up more space in your raised bed, but you can train them up a trellis to limit their footprint in your garden.

Most types of summer squash grow in a bush form. Although these plants won’t send out sprawling vines, they still require a lot of space to thrive. A healthy zucchini or pattypan plant will easily grow to four feet in diameter. So, make sure to leave enough space for your plant in your raised bed! It’s okay if some of the leaves grow over the edges of your bed, but you don’t want to plant other crops close to the base of your plants.

Winter squash tend to trail as they grow, but a few varieties have a bush form. The length of the vines varies between varieties, so make sure you look at your seed packet before planting. Some types produce short, four-foot vines, while others send out vines that grow over 12 feet long. You can train these vines to grow up a trellis or direct them out and over the edges of your raised bed.

Resist Planting Until the Soil Warms

No matter what type you plan on growing, don’t plant them in your raised bed until the soil and air are warm! Both winter and summer squash are warm-weather plants that become stressed by cold temperatures. That means you should wait until the air is consistently above 50°F (10°C) until you plant seeds or seedlings outdoors.

If you’re transplanting seedlings, you can sneak the plants into your raised bed a little earlier. Wait until the forecast is free of temperatures in the 40s (~4°C), then transplant. I recommend covering the plants with a layer of row cover to help ease their transition into their new home.

Since the seeds won’t germinate at low temperatures, avoid direct seeding until the soil is at least 60°F (16°C). However, be aware that the seeds germinate best at temperatures between 80-90°F (24-32°C). With this information in mind, I recommend transplanting your first spring planting of summer squash, then direct seeding later successions.

Watch Out for Squash Bugs

Once your squash is settled in your raised bed, keep an eye out for pests. While these fruits face few serious pests, numerous insects attack the plants’ leaves and stems. Squash bugs are one of the most common and detrimental pests. While they don’t spread disease, they can quickly weaken plants and lead to their demise. They’re especially harmful to small seedlings.

These insects appear in the garden in late spring or early summer and flock to all types of squash plants to feed. The flattened adults are about half an inch long and some shade of brown or gray. They lay clusters of bronze eggs on the leaves, and the eggs hatch into gray nymphs with black legs. Both the nymphs and adults use sucking mouthparts to pierce plant leaves and suck their sap.

If you notice squash bugs on your plants, you can pick off the adults by hand and squish any eggs you see. Make sure to check the undersides of leaves since both eggs and adults often hide there. The adults are unaffected by organic pesticides like neem oil and insecticidal soap, but these sprays will kill the nymphs.

Keep an Eye Out for Vine Borers

Squash vine borers are another common pest. While the adults of these insects are beautiful orange and black moths, the larvae are detrimental. They feed on the interior of the plant’s stem, leading to issues with water flow and wilted plants.

If you want to get these pests under control, understanding their life cycle is a good place to start. The overwintering adults emerge from underground cocoons sometime in June or July. The moths seek out squash host plants and lay eggs at the base of each plant. The eggs hatch about a week later, and the light yellow larvae bore into the plant’s stem and begin to feed. They feed on the inside of the stem for about a month, exit the plant, and then burrow a few inches underground to pupate.

Since the larvae can quickly weaken plants, preventing squash vine borers is the best way to keep your plants healthy. If you’ve dealt with these pests in the past, look out for resistant varieties with tough stems. You can also spray your garden with beneficial nematodes in temperate seasons that will kill any pests overwintering in the ground. And if you live in an area with a long growing season, try planting a round before or after these pests arrive.

If you notice your plants wilting, inspect the base of the plant for signs of vine borers. Small holes and/or sawdust-like material indicate these pests are present. Use a sharp knife to cut the base of the stem and remove the larvae. Inject the stem with Bt and seal the wound. While this method isn’t always successful, leaving the vine borers in your vine will certainly lead to a dead plant.

Plant Flowers to Attract Pollinators

If you notice misshapen zucchini or dropped blossoms, poor pollination is the most likely cause. Flowering plants can help attract pollinators to your garden, leading to better pollination of squash flowers.

Although squash plants have large flowers, they don’t start blooming until a few weeks after you plant. Planting flowers will ensure pollinators are in your garden before the plants begin to bloom. Spring-blooming annuals like calendula, sweet alyssum, and stock will provide food for bees and butterflies early in the season, and summer-blooming perennials like bee balm and anise hyssop will continue to provide pollen and nectar.

Along with planting flowering plants, avoid spraying broad-spectrum insecticides that harm bees, flies, butterflies, and other pollinators. If you choose to spray organic insecticides, apply them in the morning or evening when pollinators are the least active.

Water the Base of the Plants

Both summer and winter squash plants are susceptible to numerous fungal diseases. Powdery mildew, downy mildew, and bacterial wilt can all wreak havoc on your plants. While you can’t prevent these diseases entirely, implementing certain cultural practices decreases the odds of your plants becoming diseased.

Since fungal diseases are most likely to occur in moist environments, try your best to keep the leaves dry. Rather than using a hose to water the tops of your plants, water at the base of the plant as close to the soil surface as possible. If you want to use a watering can or hose, gently water near the plant’s stem. You can also make irrigation easier by setting up a drip irrigation system for your raised bed. Not only will this keep water off your plant’s leaves, but it will save water and allow you to automate your irrigation.

Choosing disease-resistant varieties is another way to limit the chances of disease. Not all varieties resist all diseases, so pay attention to your seed packet and choose accordingly. For example, if you know your plants often succumb to downy mildew, look for a variety that’s resistant to this disease.

Harvest Summer Squash Daily

While baseball bat-sized zucchini may look impressive, they’re not the best in the kitchen. Once zucchini and summer squash are over a foot long, they lose their tender texture and nuanced flavor. Since these fruits grow so quickly, I recommend harvesting zucchini daily or at least every other day.

Squash leaves and vines provide the perfect cover for ripe fruits, so look carefully for fruits that are ready to harvest. Zucchini and similar types will quickly wilt if they’re under six inches long, but any fruits between 6-12 inches long are ready to harvest. Once you spot a good candidate, cut the stem with a sharp knife.

Don’t sweat it, if you miss a day or two of harvesting. Just make sure to remove any large fruits so the plants can devote their energy to producing new fruits.

Succession Plant for a Continuous Harvest

Even if you do everything you can to keep your plants healthy, they’ll eventually succumb to pests, diseases, heat stress, or other issues. Most gardeners can expect to harvest zucchini and other types of summer squash for about a month per plant. If one month of fruit is enough for you, that’s great! But if you want to enjoy zucchini or pattypan squash all summer long, you should plant more than one round of seeds.

Succession planting is the practice of planting the same crop multiple days or weeks apart. For example, you may plant two zucchini plants in your garden in late May and then plant two more plants in mid-July. As the first planting begins to fade, the second planting will start producing. 

A good rule of thumb is to plant summer squash successions a month to a month and a half apart. This schedule allows you to enjoy fruits without experiencing much overlap in production. And if your new plants start producing fruits while your old plants are still growing, you can always cut out the old plants to make room for new crops.

Since winter squash takes a long time to mature and stores well, you don’t have to worry about succession planting. If you want to enjoy a larger harvest, plant more winter squash plants early in the season.