Growing Summer Squash: Plant Care and Harvesting Guide

Published June 9, 2022
Woman holding zucchini while standing at garden

Summer squash is a great plant to include in your summer garden. This category includes yellow squash and zucchini, as well as pattypan squash. Summer squash plants are known to be quite prolific, so it's possible to enjoy a bountiful harvest with just a few plants.

Growing Summer Squash Plants in Your Garden

With proper planning and care, it's not difficult to grow summer squash in your garden. The same growing methods apply to all the summer squash plants, so you can use the suggestions below with yellow, zucchini, and pattypan varieties.

Summer squash types

When to Plant Summer Squash

Summer squash plants are tender annuals that should not be planted outdoors while there is still any chance of frost.

  • Summer squash seeds can be started indoors before last frost, then transplanted into their final growing position.
  • Summer squash doesn't have to be transplanted. You can direct sow seeds into the garden as soon as the risk of frost has passed.

Where to Plant Summer Squash: Light and Soil Requirements

Summer squash plants require full sun in order to produce fruit, as well as fertile, well-draining soil that is slightly acidic or neutral. These plants tend to be large and bushy, so be sure to leave plenty of room between them.

  • Place summer squash plants in a location that receives at least six hours of direct sunlight on a daily basis.
  • Plant them in soil with a pH between 6 (slightly acidic) and 7.5 (neutral) for optimum growth.
  • Amend the soil with organic matter, such as manure or compost, prior to planting.
  • Place squash plants between two and three feet apart to allow room for plants to grow. (They tend to sprawl.)
  • If you are planting multiple rows of squash, leave three to six feet between each row.

Not all summer squash varieties grow to the same size. Follow spacing instructions on the seed packet for the particular variety you are planting.

Watering and Fertilizing Summer Squash

Squash plants need quite a bit of water. They don't have to be fertilized frequently, but it's a good idea to add fertilizer when squash plants start to bloom.

  • Summer squash require at least an inch of water every week throughout the growing season. When temperatures climb above 90 degrees, they can benefit from up to two inches of water per week.
  • When conditions are particularly dry, water your squash plants several times during the week. Every two or three days is a good frequency during stretches when there is little to no rain.
  • If your plants start to look droopy in the heat of the day, that's a sign that they need a more water.
  • When your squash plants first bloom, spoon two to three tablespoons of a fertilizer that contains equal parts of nitrogen, phosphorous, and potassium (NPK) on the ground around the base of the plants.
  • Thoroughly water your summer squash plants immediately after adding fertilizer to the soil.

Summer Squash Pests and Diseases

Summer squash is often targeted by squash vine borers, squash bugs, and cucumber beetles. Squash plants are also often impacted by powdery mildew.

  • Squash vine borers - These red and white moths lay their eggs at the base of squash plants. When the eggs hatch, the larvae bore into the base of the squash and feed, eating the plant from the inside out. If you notice them before the damage is too severe, you can cut individual larva out of the stem with a knife and cover the damaged part of the plant stem with dirt.
  • Squash bugs - These insects resemble stink bugs. They range in color from gray to dark brown, with brown and orange stripes on their abdomens. They feed on squash plants, which can cause wilt and, ultimately, kill the plants. They also lay clusters of tiny red eggs on squash leaves. As soon as they hatch, then nymphs start eating the plant. If you see adult squash bugs or their eggs on your plants, destroy them.
  • Cucumber beetles - Some of these pests are yellow with black spots and some have yellow and black stripes. They feed on all cucurbit plants, so they attack squash (summer and winter), cucumbers, and melons. Adult cucumber beetles feed on plants, which can kill them. They lay eggs in the soil around the plants. When the larvae hatch, they feed on the roots, which can also kill the plants.
  • Powdery mildew - This is a fungal disease that commonly impacts squash, as well as some other plants. Powdery mildew shows up as whitish or grayish spots on the leaves, which spread over time. Powdery mildew tends to develop when it is hot and humid. You can prune out severely infected leaves or try to treat them by applying a fungicide or natural remedy like neem oil, a mixture of milk and water, or a mixture of baking soda and Castile soap.

Tip: Once the insects that tend to plague squash arrive, it can be hard to keep your plants alive. Planting summer squash immediately after your last frost can help you get at least some harvest before these pests arrive in your area. You may also want to have some plant starts on standby to replace ones that are killed by pests.

Pruning Summer Squash

Pruning summer squash plants can help keep them productive for as long as possible during the summer growing season. Summer squash plants grow large leaves and tend to sprawl, which means that their natural foliage can impede air flow and make it difficult for pollinators to find or access the flowers. Pruning to remove unnecessary foliage can help minimize these challenges, as well as to minimize the impact of powdery mildew, which often affects summer squash plants.

  • Look at your summer squash plants to identify leaves that overlap or cross over from one plant to another. Cut them off in order to improve air flow.
  • Identify and remove leaves that are placed in a way that will make it difficult for pollinators to find the flowers that they need to access in order to pollinate the plant.
  • Look closely to see if any of your leaves have been infested with powdery mildew. Prune out leaves that have a lot of powdery mildew on them to help keep it from spreading.
  • Don't just cut off the leaves you want to remove. Instead, you need to cut off the entire stem to which each leaf you want to remove is attached.
  • Trim the leaf stems very close to the base of the plant. These stems are open tubes; you don't want to leave behind open tubes that provide shelter to unwanted bugs.
  • If a stem breaks off in the middle, go ahead and trim the rest of it off to make sure that you aren't leaving any open tubes on the plant (as that could invite bugs).

When to Harvest and Eat Summer Squash

Summer squash can be harvested and eaten at any size, though most varieties taste best when they are between three and six inches long (or around, in the case of pattypan squash). When squash become too large, they start to get mealy or tough and no longer taste good. In order to harvest them, twist the fruit until the stem breaks off or use snippers to cut the stem free from the plant. Keep part of the stem attached to the fruit.

Display of fresh summer squash at the farmers market

Propagating Summer Squash

It is best to grow squash from seed. It is possible to save seed from heirloom open-pollinated squash, but it's important to be aware that squash plants easily cross-pollinate with any other types of squash that are growing nearby. This won't negatively impact the current year's crop, but it can cause problems if you save seeds to plant next year.

  1. If you want to save seeds from a squash plant, you will need to isolate the blossom for the particular fruit from which you plant to save seeds as soon as it appears and hand pollinate rather than leaving that task to the bees.
  2. Let the summer squash fruit that you plan to save seeds from become overripe before picking it so the seeds have time to fully mature, just as you would with when saving seeds from a cucumber.
  3. Cut the squash open, scoop the seeds out, put them in a colander and rinse so you can separate them from the pulp. Place the clean seeds on a towel or plate to dry, then store in an airtight container until the next growing season.

If you don't want to deal with isolating and hand pollinating blossoms or if you are using hybrid seeds, then you'll need to purchase new squash seeds every year.

Recommended Summer Squash Varieties

There are a lot of interesting summer squash varieties to grow in your garden. Consider starting with these:

Yellow zucchini overhead group in knitted basket and wooden table
  • Early prolific yellow squash - This straightneck variety is a prolific producer of smooth-skinned yellow squash.
  • Yellow crookneck squash - This variety has a bend in the neck (hence the name crookneck), and the skin is a bit bumpy.
  • Black beauty - This green zucchini is known for producing particularly abundant yields.
  • Eight ball zucchini - This interesting zucchini produces round fruit, each of which is about three inches in diameter.
  • Sunburst - This pattypan squash produces small yellow scallop-shaped squash that taste great when they are about three inches around.

These are just a few of the many varieties of summer squash. Whether you choose one of the options listed above or select another variety, you're sure to be pleased with the results.

Good Companions for Summer Squash

As long as squash has enough room to grow, it's a good neighbor in the garden. Three sisters planting groups consisting of corn, beans, and squash have long been popular. That works well, as does placing squash near companions that can help attract pollinators or deter pests. For example:

  • Marigolds - These popular garden companions attract beneficial insects like parasitic wasps and ladybugs.
  • Nasturtiums - These beautiful edible flowers are believed to help deter squash bugs. They also attract pollinators.
  • Mint - This fragrant plant is believed to deter squash bugs. Keep it in a container so it doesn't become invasive.
  • Radishes - Planting radishes around your squash plants may help keep squash bugs at bay. The shade from the sprawling squash plants provides needed shade for the radishes.
  • Tansy - Tansy is also believed to help keep squash bugs away from your plants while also adding beauty to your garden.

Summer Squash vs. Winter Squash

Not all squash is categorized as summer squash, but all squash does grow in the summer. The name difference between summer and winter squash relates more to when the plants are ready to be eaten rather than their growing season.

  • Summer squash plants produce thin-skinned fruit that matures in less than 60 days and does not store well for the long term. Summer squash should be eaten or preserved as soon as they are large enough to eat.
  • Winter squash plants produce fruit that generally takes 90+ days to mature. Winter squash (such as butternut, acorn, and spaghetti squash) have a tough skin. They are harvested at the end of summer and can be cured to store for the winter.

Grow Squash in Your Summer Garden

Now that you know some basic facts about summer squash plants, you can enjoy growing this tasty and nutritious veggie in your summer garden. Keep an eye out for pests and make sure you give your plants all the water they need. They're sure to reward you with all the delicious squash you can eat and preserve, and they may even provide enough for you to share the bounty with others.

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Growing Summer Squash: Plant Care and Harvesting Guide