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How to Plant and Grow Zucchini & Summer Squash

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Cummins
Botanical Name
Cucurbita spp.
Grown as
Annual
USDA Zones
3a
3b
4a
4b
5a
5b
6a
6b
7a
7b
8a
8b
9a
9b
10a
10b
Toxicity
Non-toxic
Sun Exposure
Full Sun
Water Needs
Moderate
Height
1–3 feet
Spread
3-6 feet
Soil pH
Acidic
Bloom Time
Summer
Flower Color
Orange
Yellow
Special Features
Container-Friendly
Attracts Pollinators
Resilience
Heat-Tolerant
Plant Type
Vegetables
Written By: Catherine Boeckmann Executive Digital Editor and Master Gardener

Celebrate “National Sneak Some Zucchini onto Your Neighbor’s Porch Day” (August 8) the right way by mastering the art of growing zucchini, crookneck, and other summer squashes that boast perfectly tender skin and luscious summertime flavor. In this guide, you’ll learn everything you need to know to grow zucchini and summer squash from seed, how to keep these plants in containers or your garden, and how and when to harvest zucchini to maximize yields!

Note: All types of summer squash require very similar care and the tips in this guide can be applied to zucchini, yellow summer squash, crookneck squash, pattypan squash, and more.
 

zucchini squash growing in a garden
Image: Alvintus/Getty Images

Planting

When to Plant Zucchini

Zucchini and summer squash are heat-loving plants that don’t handle cold weather well and don’t take kindly to transplanting either. It’s generally best to sow these plants directly from seed in mid- to late spring when the risk of frost has passed, the soil has warmed to at least 65° to 70°F, and air temperatures are at a comfy 60ºF or above. Don’t start the seeds earlier than this, as they won’t germinate!

If desired, zucchini seeds can also be started indoors in biodegradable pots about 2 to 4 weeks from the last spring frost date — or they can be grown from nursery-started plants. Either way, don’t rush transplanting. The weather should be warm and the plants properly hardened off before they’re moved outside.

Gardeners who regularly struggle with pests like squash vine borers may want to skip spring planting altogether and sow zucchini seeds outdoors in midsummer instead. This can help to minimize pest problems as long as you start the seeds early enough that the plants still have time to mature before frost.

Where to Plant Zucchini

Zucchini need to be bathed in warmth and sunshine to thrive, so make sure to locate them in an area that receives at least 6 hours of direct sun per day and has rich, moist soil. It’s also wise to position these plants in a sheltered location that’s protected from strong winds to make it easier for bees and pollinators to move between zucchini blossoms. Growing these plants near flowers and herbs can also increase pollinator activity and help you get a larger harvest!

Depending on your space, you can grow zucchini in raised beds or in-ground gardens or you can plant them individually in containers that are at least 5-gallons in size. Just make sure to mix plenty of compost or well-rotted manure into planting sites beforehand to give these heavy feeders something to grow on.

How to Plant Zucchini

To sow zucchini seeds outside, plant bush-type zucchini seeds 1-inch deep and 2 to 3-inches apart in rows spaced 2 to 3-feet from each other, or plant 3 to 4 seeds together in mounds spaced 3 to 6-feet apart. If necessary, use row covers, plastic milk jugs, or cold frames to shield these tender plants early on and then thin the seedlings out to 2 to 3-foot spacing or 1 ot 2 plants per mound once the seedings sprout leaves. Vining-type zucchinis, on the other hand, can be planted slightly closer together if you install a trellis at planting time to keep the vines more manageable.

To sow zucchini seeds indoors, plant 2 seeds per 4-inch biodegradable pot and thin to one plant per pot when the true leaves form. Harden the seedlings off carefully when the weather warms and be gentle with the roots when transplanting. As with directly sown seeds, bush-type transplants should be positioned about 2 to 3-feet apart for proper growth.

After planting zucchinis, keep them well-watered and add a layer of mulch to reduce weeds and conserve soil moisture.

See our video showing how to grow the perfect zucchini every time!

 

Growing

Watering

Zucchini thrives in moist soil and should be watered thoroughly, frequently, and consistently with at least 1-inch of water per week. Watering deeply and diligently is best for fruit set and can help you avoid misshapen or underwhelming harvests. Plants grown in pots need more frequent watering than plants in the garden, but you can significantly slash watering needs by adding a 1 to 3-inch layer of mulch when zucchini plants are a few inches tall.

Powdery mildew can be a big problem with zucchinis, but you can reduce mildew issues by watering plants at the soil line and keeping their leaves as dry as possible!

Fertilizing

Like other heavy-feeders, zucchinis and summer squash grow best when the soil is enriched with compost or aged manure before planting. When the first flowers appear, simply side dress the plants with a balanced or low-nitrogen fertilizer.

Pruning or Maintenance 

During the growing season, remember to stay on top of weeds to reduce plant competition. Mulching can make this task much easier. If you’re growing vining zucchinis on a trellis, you may need to gently help the vines start to climb.

Unlike some veggies, zucchinis often won’t fruit without pollinators or they may produce a misshapen harvest when pollination is inadequate. Companion planting and keeping your garden pesticide-free should naturally increase pollinator activity and fruit set. If you don’t see any pollinators around, you may need to hand-pollinate the flowers yourself with a Q-tip or old makeup brush.

Seasonal Care

Zucchinistend to produce only male flowers at first and pollination can be slow to start — particularly in cool or damp weather. Warming the soil before planting with black plastic mulch can speed things along, as can row covers and grow tunnels. However, zucchinis should be uncovered completely once their flowers start to bud out to ensure pollinators can get to work.

Harvesting

When to Harvest

Most varieties of zucchini and summer squash take about 60 days after planting to start bearing fruit and those fruits are usually ready to be picked about a week after flowering. That said, there is some variabiliy in harvesting times, so always check seed packets for more exact information.

For best flavor and texture, harvest zucchini and squash when the fruits are about 6 to 8-inches long. Larger fruit can look impressive, but it has little flavor and the skins get quite tough. Once fruiting begins, check zucchini plants regularly and often as it’s easy to overlook a hidden zucchini and wind up with massive, but tasteless, fruit!

How to Harvest

When harvesting, cut zucchinis off the vine with a sharp knife and leave about 1-inch of stem attached to each fruit. Resist the temptation to harvest zucchini by pulling on the fruit as this can damage your plant.

If your zucchini are producing too well, you can slow down production by harvesting the fruit when it’s still small or removing all the male flowers. Zucchini flowers are perfectly edible and can be used as salad toppers or stuffed, battered, and fried. Towards the end of the season, harvest all remaining zucchini before frost hits as the plants and fruit won’t survive a cold spell.

Storage

Fresh zucchini and summer squash has a relatively short shelf life and can be stored, unwashed, in a plastic or paper bag in your fridge’s crisper drawer for about 10 days. If you end up with more zucchini than you can use straight way, you can also pickle it or blanch and freeze it for up to 3 months.

zucchini blossoms

Pests and Problems

Zucchini produces well, but you MUST keep an eye on the plant for pests. If you ignore your plants, the pests will come, and you must get ahead of them before they arrive!

Common Problems

  • Fruit and flower drop can occur if plants are temperature-stressed or underwatered, or if they’re struggling due to lack of pollination. It’s also perfectly normal for the first few zucchini flowers to fall off the plants without producing fruit.
  • Wilting may indicate that zucchinis need more water, but it can also occur due to activity from pests like squash vine borers.

Common Pests

  • Squash bugs feed on sap, weakening plants and threatening fruit production. Protect plants when the bugs are most active in early summer by using row covers or fleece, and then continue to check for eggs at least twice a week. If you find any eggs, rub or scrape them off with your fingers, while adult bugs can be dispatched by knocking them into a bucket of soapy water. 
  • Squash vine borers burrow into zucchini stems, which causes stems to rot and foliage to wilt. These pests are most active earlier in the summer and can be rebuffed with row covers or by wrapping plant stems in foil to prevent eggs from being laid. If you suspect the grubs have found their way into your plants, cut them out by making vertical cuts into the zucchini stems with a sharp, sterilzied knife or inject BT thuricide directly into the stem itself.

Plant Diseases 

  • Powdery mildew can be an issue on zucchini leaves late in the season and is most common when plants are overcrowded, watered from the top-down, or exposed to extended periods of high humidity. If plants become infected, remove the damaged leaves immediately and treat plants preventatively with a spray made of 1 part milk and 2 parts water appied at 2 week intervals.
  • Blossom-end rot can turn the base of squash and zucchinis black and mushy with rot and spoil your havest. This condition is usually caused by irregular watering, but it can also indicate that zucchini plants are calcium starved.

Watch this excellent video for tips and tricks to sidestep common squash problems so there’s no barrier to your successful harvest!

Types

Zucchini come in bush-type forms, which are best for containers and growing in rows, or vining-type plants that can be grown on trellises. Here are popular picks and what makes each stand out.

  • ‘Cocozella (di Napoli)’: A heirloom zucchini with dark green, slender fruits and excellent flavor.
  • ‘Goldbar’: A yellow summer squash variety with a sweet and nutty flavor.
  • ‘Ronde de Nice’: A funky, French heirloom, this plant produces globular fruits — and lots of them!

Wit and Wisdom

  • The word “squash” derives from askutasquash, the Narragansett Native American word meaning “eaten raw or uncooked.”
  • So-called squash bees—Peponapis and Xenoglossa—are excellent pollinators, especially for zucchini. Look for them among the flowers in the first few hours after sunrise.
  • Squash is technically a fruit because it contains the plant’s seeds, but for culinary purposes, it is treated as a vegetable.

Vegetables

About The Author

Catherine Boeckmann

Catherine Boeckmann

Executive Digital Editor and Master Gardener

Catherine Boeckmann loves nature, stargazing, and gardening so it’s not surprising that she and The Old Farmer’s Almanac found each other. She leads digital content for the Almanac website, and is also a certified master gardener in the state of Indiana.

Read more from Catherine Boeckmann

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Comments

<span>Betcb</span> Mon, 06/02/2014 - 15:23
My squash vines are huge and are blooming now. We have them in a raised bed with tomato cages upside down. They are already getting towards the top. Does it matter if the vines are large or should we take off some leaves for the sun to get to the blooms?
<span>Tambra</span> Sat, 05/31/2014 - 14:48
We have beautiful healthy yellow squash plants. We still do not have any flowers on them at all. We have had unusually cool temps for May and lots of wet weather . Should we be concerned that we have no flowers yet? Why don't we ? What can we do ? Thanks
<a title="View user profile." href="/author/editors">The Editors</a> Mon, 06/02/2014 - 09:46

You are correct in saying weather may play a role. It has been a cool, wet spring in many parts of the country. Cool weather with temperatures below 75 degrees Fahrenheit can delay flowering. Another reasons could include dry soil or overcrowding. 

Sometimes a plant won't produce flowers if it receives too much nitrogen. Squash likes low nitrogen and higher phosphorus and potassium. If you think it might be too much nitrogen, you might apply some amendments that contain phosphorus and potassium to balance the nutrients. Ask a local garden nursery for options and timing.

Once it's warm enough, expect most summer squash to flower 35 to 45 days from germination.

 <span>Janet Stinson</span> Sat, 05/31/2014 - 11:16
My neighbor has a problem with his squash plants. Oddly, the plant leaves start turning brown around the edges and eventually die, but the squash keep producing nicely. Local agents mention "blight", but otherwise confess that they do not know the reason. Is it simply some sort of stress on the plants due to improper watering practices, or maybe soil problems, since it has been happening for the last two seasons? Should he even worry about it?
<a title="View user profile." href="/author/editors">The Editors</a> Mon, 06/02/2014 - 09:31

Brown leaf edges can be caused by many things, including a period of cold temperatures (below 50 F) and wet weather. If there are no signs of spots on the leaves, or wilting, and the plant is doing fine in production, then it's probably not something to worry about. If your friend is curious, though, he might talk to his county's Cooperative Extension. Sometimes they will do tests to check for plant diseases, for a fee. For a list of agencies, see: http://www.almanac.com/content/cooperative-extension-services

 <span>Betty Voltin Beard</span> Tue, 05/27/2014 - 11:25
I have been trying for 2 years to grow zucchini and the blossoms fall off and no produce grows. what am I doing wrong.
<a title="View user profile." href="/author/editors">The Editors</a> Wed, 05/28/2014 - 10:52

Hi, Betty: Sounds like a pollination issue, if it's now happened for two years running. See the first item under "Pests" at the beginning of this forum above. You can identify females by the tiny fruit at the base of the flower. Happy zukin'! You can do it!

 <span>Matty</span> Fri, 05/09/2014 - 09:52
Hi there - i am a real newby gardener - green behind the ears if you know what i mean:). i planted some cozzelle zucchini. the first two 'cotyledons' or mini leaves are coming up for several of the plants but some are turning a bit yellow and it seems like it might be spreading. i planted them 2 weeks ago when it was still chilly at night. is it mold? or blossom end rot? am i watering too much? please help? thank you Matty
<span>Kgardener</span> Wed, 04/30/2014 - 22:02
I started yellow squash and zucchini seeds and the yellow squash plants 6 weeks out are enormous and healthy with several green 4 inch leaves. The zucchini on the other hand is short with only 2 marginally healthy looking leaves, the others fell off or I plucked off perhaps wrongly because they were yellow or dry and brown inorder to save the plants energy to produce healthy leaves. But now it's starting to flower which seems way too early. Do I pluck the flowers? I've already plucked a few I feel like there's nothing left to this poor plant. Will the plant recover or should I start over?
<a title="View user profile." href="/author/editors">The Editors</a> Fri, 05/02/2014 - 14:24

Even if conditions were exactly the same for both squashes, the results may not be the same.

Zucchini seed germination requires a minimum soil temperature of 60°F, according to several sources, with a pH of 6.0 to 7.5. BTW, one even advices starting both squashes in the ground, to avoid transplanting failure.

It's difficult to know eactly what went wrong. See what happens with the existing seedlings, and try again and, if you do, save a couple of seeds to set directly into warm soil in the garden.

Good luck!