蜜桃恋人

How to Grow Zucchini & Summer Squash Plants: The Complete Guide

Photo Credit
Getty Images
Botanical Name
Cucurbita spp.
Plant Type
Vegetable
Sun Exposure
Full Sun
Soil pH
Slightly Acidic to Neutral
Bloom Time
Summer
Flower Color
Orange
Yellow

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Planting, Growing, and Harvesting Zucchini & Summer Squash

Catherine Boeckmann

Zucchini is known to be staggeringly productive. But there are some pitfalls, such as poor pollination and pests, to avoid if you wish to have a prolific harvest. In our growing guide, we鈥檒l cover planting through harvesting and also share tips and tricks to sidestep common problems.

About Zucchini

Note that squash is generally divided into two categories: summer squash (harvested in summer) and winter squash (harvested in autumn). The skin of summer squash is edible, unlike the skin of winter squash. Most summer squash now come in bush varieties, which take up less space, whereas winter squash are vining plants that need more space. 

Zucchini are warm-season crops with compact, bushy or trailing varieties to pick from. Compact types are good for containers 鈥 indeed, anywhere you don鈥檛 have a lot of space 鈥 while trailing types may be trained as climbers to grow up supports such as trellis or wire mesh.

Green zucchini are always going to be popular, but try a few of their more charismatic cousins as well, including varieties with yellow fruits, striped or ribbed fruits, and even round fruits.

This guide focuses on summer squash. Summer squash varieties include zucchini, yellow squash (straightneck squash), and crookneck squash. Note: All types of summer squash require very similar care, so even though we mainly refer to zucchini on this page, consider it to be applicable to whatever summer squash variety you鈥檙e growing!

Zucchini is a vigorous grower. While each plant will produce several squash during peak season, you鈥檒l typically find that one or two zucchini plants will produce a 鈥渂umper鈥 (unusually large) crop, leaving you to give the squash away to neighbors or bake lots of zucchini bread!

Image: Alvintus/Getty Images
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Planting

Zucchini are members of the squash family, so they need to be bathed in warmth and sunshine to thrive. Shelter them from strong winds, too, so bees and other insects can go about pollinating the flowers in peace.

Pick a location with full sun, shelter from the wind for good pollination, and soil that is moist (not soggy) and well-draining. Squash also produces well if well-fed. Mix aged manure and/or compost into the soil before planting. Learn more about preparing soil for planting.

Their robust growth and big leaves make them hungry feeders. Add plenty of garden compost or well-rotted manure to the soil before planting. In fact, you can even plant zucchini on top of a compost heap 鈥 if you won鈥檛 be needing it till fall, that is.

Or prepare planting pockets: a few weeks before planting, dig out a hole, fill it with compost, then return some of the soil, along with a handful of organic fertilizer. The nutrient-rich filling will prove a veritable feast for the plants growing in it!

When to Plant Zucchini

  • Wait to plant seeds or transplants in the ground until the soil is at least 65 to 70 degrees. This may be mid-spring for some regions, but often, it’s fine to plant by late spring. (Don’t start too early, as the seeds will not germinate in the cold, and you’ll do the plant no favors.)
  • Direct-sow seeds (i.e., directly into the ground) when all danger of frost has passed, and the air and soil are at least 60潞F. See your last frost date.
  • If you wish to start seeds indoors, start seeds in peat pots 2 to 4 weeks before your last spring frost; note that squash seedlings do not always transplant well; handle the roots gently. Fill pots or plug trays with potting mix and sow one seed per pot or plug on its edge. They will germinate quickest with a little warmth, but so long as you can guarantee a frost-free environment, they鈥檒l eventually push through.
  • Warm the soil with black plastic mulch once the soil has been prepared in early spring.
  • Do not rush to plant zucchini. Consider planting a few seeds in midsummer to avoid problems from squash vine borers and other early-season pests and diseases.

How to Plant Zucchini

  • Direct sow seeds in level ground 1 inch deep and 2 to 3 inches apart.
  • Or, sow 3 or 4 seeds close together in small mounds (or hills; the soil is warmer off the ground) in rows 3 to 6 feet apart.
  • If necessary, use row covers, or plastic milk jugs, or cold frame protection in cold climates for the first few weeks of spring.
  • Thoroughly water after planting.
  • Adding a layer on top of mulch (such as garden compost) to lock in soil moisture.
  • You can also sow into seed flats or trays to separate out and pot on after germination. Do this as soon after germination as you鈥檙e able to handle them before the roots become entangled. Fill your pots and, holding the seedling by its leaves, not the stem, feed in the potting mix around the sides. Firm in and water.

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

Growing

  • Mulch to discourage weeds, retain moisture, and protect shallow roots.
  • Zucchini thrive in moist soil. Water thoroughly, frequently, and consistently, with at least 1 inch per week. Water diligently when fruit form and throughout their growth cycle. The soil needs to be moist 4 inches down, so long soakings are best. Misshapen squash results from inadequate water or fertilization. 
  • Keep your zucchini well-watered, and top up mulches occasionally to help lock in soil moisture for longer. Plants tend to produce only male flowers at first, and pollination can also be slow to start with anyhow, particularly in cool or damp weather.
  • Remove any weeds that manage to poke through. To keep plants tidy, cut off any dead or shriveling weeds. Top up mulches, using organic matter such as garden compost, to help roots stay cool and moist.
  • When the first blooms appear, side dress with a balanced fertilizer.
  • Poor pollination by bees can be an issue. Squash flowers will not bear fruit or bear small fruit if not pollinated. Most squash plants produce both male (these appear first, on long thin stalks) and female flowers (these have an immature fruit behind them). To fruit, pollen from the male flowers must be transferred to the female flowers by bees鈥攐r by the gardener. Pollinate the female flowers manually with a cotton swab or add plants that attract bees near the squash.

Growing Zucchini and Summer Squash in Containers

The ever-increasing number of compact varieties suited for containers provide options for any taste and space. Bush plants are generally better suited to containers, but in a large pot with space to spread, vining squashes can produce a successful harvest.

Prepare a 5-gallon or 14-inch-diameter pot with rich potting mix for each variety of squash that you want to grow. When the soil temperature reaches around 70掳F, or 2 weeks after the last frost date, direct-sow two seeds of the same variety 1 inch deep into the container and water to dampen. (Transplant homegrown or purchased seedlings if you want to jump-start the growing season.) Following germination, remove the weaker plant by cutting its stem; this is less disturbing to the roots. Water regularly to keep the soil moist. If you鈥檙e growing vining squashes, insert a trellis into the container for the plant to climb later.

About 6 weeks after the seeds have been planted, apply fertilizer. After the first true leaves appear (those after the initial two), apply a slow-release pellet fertilizer, according to the label鈥檚 directions. Follow up with a weekly dose of balanced fertilizer, based on the label鈥檚 guidance for the pot size. When watering, avoid getting water on the leaves. Water the soil 1 inch per week directly or set the container in a bucket or tub of water and allow it to be absorbed. As the plants grow, train the vines (if that type) onto the trellis or other support. Use string to gently secure them.

Types

  • 鈥楥补蝉丑蹿濒辞飞鈥: cylindrical zucchini type
  • 鈥楥ocozella (di Napoli)鈥: zucchini heirloom; dark green, slender
  • 鈥楪辞濒诲产补谤鈥: yellow summer squash
  • 鈥楬orn of Plenty鈥: yellow crookneck type
  • 鈥楽耻苍产耻谤蝉迟鈥: pattypan/scallop type
  • 鈥楾颈驳谤别蝉蝉鈥: zucchini type

Harvesting

Harvest summer squash when tender and a bit immature (6 to 8 inches long) for more flavor. Believe us, oversize squash has very little taste. Many people wait too long to harvest. If you have ever had a negative experience with zucchini before, it鈥檚 probably because they were left to become bruisers.

  • Most varieties average 60 days to maturity, and are ready as soon as a week after flowering. (Check the seed packet for more exact information.)
  • Cut (do not break) fruit off the vine with a sharp knife, or you risk damaging the soft stem of the plant. Leave at least 1 inch of stem on the fruit.
  • To slow production, harvest fruit when small and/or remove male flowers.
  • If the harvest is interrupted (say, by your vacation), remove large squash on your return to reduce demands on the plants for moisture and nutrients.
  • Complete the harvest before the first fall frost; summer squash is highly susceptible to frost and heat damage.

In fact, the flowers make good eating too, typically stuffed or simply battered and then fried. But only pick the male flowers 鈥 that鈥檚 the ones without a bulge behind them 鈥 or else you won鈥檛 get any fruits!

How to Store Zucchini

  • Fresh summer squash has a relatively short shelf life. Store unwashed zucchini in a plastic or paper bag with one end open to encourage air circulation, and pop them in the refrigerator crisper drawer. They鈥檒l keep for 10 days.
  • Too much zucchini? Freeze it! It will keep for 3 months. See how to blanch and store zucchini in the freezer!

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Wit and Wisdom

  • The word 鈥渟quash鈥 derives from askutasquash, the Narragansett Native American word meaning 鈥渆aten raw or uncooked.鈥
  • So-called squash bees鈥Peponapis and Xenoglossa鈥攁re 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鈥檚 seeds, but for culinary purposes, it is treated as a vegetable.
  • August 8 is National Sneak Some Zucchini on Your Neighbor’s Porch Day!

Pests/Diseases

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

Pests
Two troublemakers often pay an unwelcome visit, usually early in the season. 

  1. Squash bugs feed on sap, weakening plants and threatening fruit production. Protect plants when the bugs are most active, early on in the summer, by using row covers or fleece. Then continue to check for eggs at least twice a week. Rub or scrape off the eggs. Adult bugs can be knocked or shaken off plants into a bucket of soapy water. (If you keep chickens, offer them a treat!)
  2. Squash vine borers are found in the eastern half of North America. They burrow into stems, causing them to rot and foliage to wilt. They are most active earlier in the summer. Row covers can help keep them off, or wrap stems in foil to prevent eggs from being laid at the base of plants. It’s possible to cut the grubs out by making vertical cuts into the stem using a sharp knife. Once you’re done, bury the stem with moist soil to encourage new roots.

Here’s a helpful squash borer tip from reader James W: 鈥淣o prevention is perfect. What I do is to start another zucchini indoors for planting after July 1st in zone 5. The squash borer has completed her egg laying by then, and the rest of the summer is uneventful, to the zuke at least.鈥

Diseases

  1. As far as diseases go, powdery mildew can be an issue on the leaves later in the season. It’s a common fungal disease that forms a white powdery coating on both sides of leaves. Usually, growth stalls. A common reason for powdery mildew is irregular watering, so stay consistent. If plants do become infected, remove affected leaves straight away. A great way to prevent powdery mildew altogether is to mist leaves with a solution that is 1/3 milk to 2/3 water. Spray the milky mixture onto all surfaces, early on a dry and sunny day. Repeat every 10 to 14 days throughout the growing season. 
  2. Blossom-end rot is an occasional issue as well. If the blossom ends of your squash turn black and rot, then your squash have blossom-end rot. This condition is caused by uneven soil moisture levels, often wide fluctuations between wet and dry soil. Uneven watering affects the calcium levels of the fruit. To correct the problem, water deeply and apply a thick mulch over the soil surface to keep evaporation at a minimum. Keep the soil evenly moist like a wrung out sponge, not wet and not completely dried out.

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

Recipes

Zucchini Bread
Summer Squash Pickles
Zucchini Brownies
Lemon-Zucchini Muffins
Zucchini Pancakes
Zucchini Relish
Fresh Tomato and Zucchini Au Gratin
Breaded Fried Zucchini Rounds

Cooking Notes

  • Zucchini can be overwhelming once it starts producing. While zucchini bread is great, there are many other ways to enjoy this summer squash! See our Best Zucchini Recipes.
  • Squash flowers are edible and make a tasty treat when fried in a light batter.
Vegetables
About The Author

Catherine Boeckmann

Catherine Boeckmann loves nature, stargazing, and gardening so it鈥檚 not surprising that she and The Old Farmer鈥檚 蜜桃恋人 found each other. She leads digital content for the 蜜桃恋人 website, and is also a certified master gardener in the state of Indiana. Read More from Catherine Boeckmann
 

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Comments

Research has shown that mulching with newspaper topped with straw works best. Tightly secured row covers will add extra protection against the adult moth to lay eggs close to the squash plants.

KimberlyDS (not verified)

10 years ago

First attempt at butternut squash in Tallahassee, FL (zone 8b); planted seeds in early Sept. I read that b-nut can be planted in the fall here, but now I am worried that we might have an early frost this year, with temps dipping into the 40s already this weekend. There are many 1-2 inch-long squash at this point.

Did I plant too late? Is there any chance my squash will make it to full maturity? How long does it take from the 1-2 inch stage to the full grown stage? And could covering them over night help? Do you have any suggestions?

Covering your plants to protect against frost is a must. Once I even used a candle under a tarp covering my avocados to fend off any frost. and easy fix is to cut the bottoms off of plastic soda bottles and set them into the ground over the plants and then try to cover them with straw or a tarp.

It's recommended to plant winter squash in Aug. if you live in central FL. Sept. planting if you live in southern FL. You may have to cover your plants if you have an early frost. With some luck you may be able to harvest a few butternut squashes before winter.
 

Marcella Womac (not verified)

10 years 1 month ago

Hello, i planted squash this year in the spring and mid summer, the ones in spring got the squash bore worm and they died and i read that it is best to plant in mid summer so i did but those plants were doing well and then the fruit started getting green worms in them. i don't know what kind they were i did fine a few squash bore worms in the stems but i don't know where the the green worms that bored into the fruit was coming from or how to get rid of them. can you help me so next year i can prepare to combat them.

Especially if you live in the South, the green worms in the fruit might be pickleworms--pale green with brown heads, up to about 3/4" long. They might have reddish-brown spots, depending on the stage of larval development. To help prevent them from boring into the fruit, spread mulch around or keep the fruit off of the ground. They like to feed at ground level. They might also tunnel into flowers, buds, and stems, but prefer the fruit. A larva will eventually spin a thin cocoon, perhaps rolled in a leaf, and pupate. Adult brownish-yellow moths emerge in about 7 to 10 days; they are active at night. Early-maturing varieties are good to combat pickleworm, so that they mature before the peak of the pickleworm population. Also, because the moths are active at night, covering the squash with row cover overnight will help to prevent them from laying eggs on your squash. Remove the cover during the day, to allow pollinators such as bees to visit the flowers. Some varieties of squash are more resistant to pickleworm, such as Butternut 23, Summer Crookneck, Early Prolific Straightneck, and Early Yellow Summer Crookneck.
 
For more information, see:
 
http://entnemdept.ufl.edu/creatures/veg/pickleworm.htm
 
If the larvae you see are not pickleworms, perhaps they are melonworms? Green larvae, usually with two white stripes (depending on larval stage). But these usually attack leaves, or sometimes the surface of the fruit. It's less common for them to tunnel into the fruit. See:
 
http://ipm.ncsu.edu/AG295/html/pickleworm_melonworm.htm
 
http://entnemdept.ufl.edu/creatures/veg/leaf/melonworm.htm

thank you for this information you described the worms exactly i will try the mulch next time i plant. fall is here now. looking forward to the color changeing of the trees. thank you again.
marcella

blue gum (not verified)

10 years 1 month ago

i have been growing good yellow sunburst squash now i am getting a lot of green & green & yellow throw them now why.
i have my squash is next to my zucchini could they cross pollinate

Hi, Blue Gum: Yellow squash and zucchini certainly will cross polinate, but the results are usually not seen until the fruit that grows from cross pollinated seeds in the following year. So this may be something that was in your seeds. It also might be because some sort of stress is changing/expanding the tiny amount of green that is on yellow sunbursts anyway. Sounds like cross pollination at some point, though.