Zucchini Plant Guide: How to Grow Zucchini, Pick It Young and Eat the Blossoms

To grow a zucchini plant, wait for the last frost to pass and for soil two inches down to hit 70 F, then plant the seed 1/2 to 1 inch down. Thin to one plant every 18 to 36 inches in most sources (Minnesota allows 8 to 12). Zucchini needs bees: the first blooms are male, and fruit sets once female flowers open a week or two later. Pick most varieties at about 6 to 8 inches long, checking the plants every day or two, since the fruit swells fast. The flowers are a crop too: take mostly male blossoms the day they open and leave a few to pollinate.

When to plant zucchini

Zucchini seed goes in after your last frost and only into warm ground: at least 70 F at a two-inch depth, by the University of Minnesota's rule and Johnny's Selected Seeds' tech sheet. The seed company Botanical Interests gives a calendar version: sow a week or two past the average last frost, into soil at 70 to 85 F. Johnny's keeps sowing every 30 days until 8 weeks ahead of its first fall frost.

Each freeze date below is the day a station's NOAA normals (1991 to 2020) give even odds of a later 32 F night, so a frost after it is a coin flip.

Zucchini sowing dates at four NOAA stations

Station	Spring freeze date	Direct sowing (Botanical Interests)	Indoor start, if used (3 weeks ahead)	Last sowing (Johnny's)	Fall freeze date
Minneapolis-St. Paul, MN	Apr 23	Apr 30 to May 7	Apr 9 to Apr 16	Aug 23	Oct 18
Baltimore (BWI), MD	Apr 10	Apr 17 to Apr 24	Mar 27 to Apr 3	Sep 5	Oct 31
Raleigh-Durham, NC	Mar 31	Apr 7 to Apr 14	Mar 17 to Mar 24	Sep 9	Nov 4
Dallas-Fort Worth, TX	Mar 8	Mar 15 to Mar 22	Feb 22 to Mar 1	Sep 29	Nov 24

Direct sowing = the spring freeze date plus 1 to 2 weeks, our reading of Botanical Interests' "1 to 2 weeks after your average last frost date"; its soil rule still applies. Indoor start = 3 weeks before that window, our count from the University of Maryland's and Hudson Valley Seed's 3 weeks, assuming you plant out in the sowing window. Last sowing = the fall freeze date minus 8 weeks (56 days), our count from Johnny's tech sheet; our squash and pumpkins guide counts back Clemson's roughly 55 days to harvest instead, so its dates fall one day later.

The soil overrules the calendar. Minnesota's freeze date is Apr 23, yet the University of Minnesota expects soil at 70 F only in late May across most of the state and early June in the north; seed sown into cold soil will not sprout. A soil thermometer settles it; a hardiness zone is no substitute for a station's frost date.

Seed or transplants? Minnesota and Botanical Interests prefer sowing in place, since moved seedlings suffer root damage; Johnny's allows transplants for short seasons, and Maryland starts them in 3-inch pots 3 weeks ahead.

How far apart to plant zucchini, and soil and water

Space zucchini plants 18 to 36 inches apart in most sources, with 3 to 6 feet between rows. Minnesota is the outlier: it thins to 8 to 12 inches and gives the vines about two or three feet on each side. Seed goes 1/2 to 1 inch deep: Minnesota about half an inch, Illinois and NDSU an inch.

Soil, sun and water. Johnny's wants fertile, well-drained ground at pH 5.8 to 6.8, Minnesota 6.0 to 6.5. Maryland works in compost, side-dresses when female flowers appear, and wants 6 hours of sun at minimum (8 to 10 preferred). Minnesota and Johnny's both plan on about an inch of water a week, by drip or soaker hose so the leaves stay dry. Black plastic warms the soil for an earlier start (Minnesota, Maryland), and a row cover keeps off chill and early pests until the plants flower, when it must come off for the bees.

How the zucchini sources compare

Who says it	Depth	Spacing	Soil to sow	Days to harvest	Pick at	Repeat sowing
U. of Minnesota	About 1/2 in	Thin to 8 to 12 in; hills 5 to 6 ft apart	At least 70 F at 2 in	Not given	Size you prefer, before seeds and skin get large and hard	Second half 3 weeks later; early July against borers
U. of Illinois	1 in	24 to 36 in; hills 48 in	After frost danger	Usually 4 to 8 days after flowering	Most types 6 to 8 in long, 2 in or less across	Some gardeners plant twice (early and late summer)
U. of Maryland	Not given	2 to 3 ft, rows 3 to 5 ft	After frost, soil warmed	50 to 65 from transplant	About 6 to 8 in long, 1.5 to 2 in across	Second crop July 1 to 15; plant 2 to 3 times
NDSU	1 in	Sow 4 to 6 in, thin to 18 to 24 in; rows 6 ft	Warm soil, frost past	Not given	Small, skin tender	Not given
Johnny's (seed company)	1/2 to 1 in (tech sheet)	18 to 24 in, rows 6 ft (key growing info); 12 to 24 in, rows 5 to 6 ft (tech sheet)	At least 70 F	Varies by variety; about 14 fewer if transplanted	6 to 8 in long	Every 2 to 3 weeks, if needed (key growing info), or 30 days (tech sheet)
Botanical Interests (seed company)	1/2 to 1 in	2 to 3 seeds per mound; rows 3 to 4 ft	70 to 85 F; 1 to 2 weeks after last frost	52 to 60 ('Costata Romanesco')	Under 12 in ('Costata Romanesco')	Not given
Hudson Valley Seed (seed company)	Up to 1 in (lower figure blank on the listing)	24 in; rows 36 in	After frost	52 ('Costata Romanesca')	6 to 8 in long	Every 3 to 4 weeks

Why zucchini flowers fall off: pollination and fruit set

The first zucchini flowers usually drop without fruit because they are male: Maryland says a squash plant opens only males for the first 1 to 2 weeks, until a female shows up. Fruit comes only from female flowers, and, parthenocarpic varieties aside, only after a bee carries pollen to them.

Telling them apart. A male flower sits on a long, thin stalk; a female grows close to the main stem with a small swelling under the petals that becomes the zucchini (Minnesota, Illinois). Males usually far outnumber females: about 3 to 1, says the University of Saskatchewan.

When fruit fails. Misshapen, withered or blackened first fruits, common in some varieties, mean poor pollination and usually clear up as more males open (Johnny's); cold, rainy or cloudy weather can keep bees home (Minnesota, Maryland). Maryland's fixes: patience, well-tended plants, flowers nearby for pollinators, no spraying during bloom, or a parthenocarpic variety, which sets fruit without pollination and can stay under row cover all season.

Hand pollination. If bees are scarce, Saskatchewan peels the petals off a male flower and dabs its pollen onto the center of each open female.

Picking zucchini: size and how often

Pick zucchini at about 6 to 8 inches long: Illinois, Maryland, Johnny's and Hudson Valley Seed all name that length, and Illinois and Maryland add a width of 2 inches or less (Maryland says 1.5 to 2). A fruit is often ready just 4 to 8 days after its flower opens, says Illinois, so Illinois checks every 1 or 2 days; Maryland looks daily, Johnny's 2 to 3 times a week.

Too big? If your thumbnail cannot dent the rind, the fruit is over-mature (Maryland). Take it off anyway, since large fruit left on the plant slows the next ones (Minnesota, Illinois), and never pick from wet vines (Minnesota).

Keeping it. The sources give 2 to 3 days in the crisper (Illinois) to up to 2 weeks in a humid cold room at 40 to 50 F (Johnny's, a grower's figure). Our reading: in a home refrigerator, plan on a few days.

Zucchini blossoms: which flowers to pick and how to use them

Pick zucchini blossoms on the day they open, and take mostly the male flowers: Minnesota says removing males does not cost you any fruit, and Illinois says to leave a few on the vine for pollination. Cut each one with about 1 inch of stem (Illinois). A female flower is edible too, but each one picked is a zucchini lost.

• Which flower. Male: thin, trim stalk, nothing under the petals. Female: thick stalk with a small zucchini at the base (Illinois, Johnny's, Botanical Interests).
• When and where to cut. Johnny's picks in the mid to late morning once the flowers are wide open and clips 1 to 2 inches below the base; Illinois cuts at midday with the petals open. Botanical Interests picks just before you cook.
• Before taking every male. Saskatchewan makes sure the open females are pollinated first, by hand if need be.

Keeping and cooking. Illinois rinses the flowers and holds them in ice water in the refrigerator, where they last a few hours or at most 1 or 2 days. Johnny's suggests them stuffed and fried, or sliced into soups, omelets, salads and pasta.

Italian zucchini types: Costata Romanesco, cocozelle and Caserta

Illinois groups zucchini with cocozelle and Caserta as the Italian marrows, long squash usually in shades of green. Of these, 'Costata Romanesco' is the one the seed companies here describe most: ribbed, gray-green fruit with a nutty flavor raw or cooked (Johnny's, Hudson Valley Seed), ready in 52 to 60 days. Johnny's marks it among its varieties for edible flowers, and Botanical Interests calls it a good source of male blossoms. The sellers disagree on its habit: semi-vining at Johnny's, a bush at Hudson Valley.

Lost zucchini to vine borers before? Our squash and pumpkins guide covers tromboncino, a long Italian squash it suggests where borers kill zucchini.

Growing zucchini in containers

A zucchini plant can grow in a container of at least 4 to 6 gallons with 8 to 12 inches of depth, the size class where the University of Maryland files summer squash. Penn State Extension disagrees: it lists zucchini among the crops better suited to the ground than to a pot.

Our reading: both can be right. Hudson Valley lists 'Costata Romanesca' as 48 inches wide, yet Botanical Interests rates it good for containers. In a pot, choose a compact bush type, go large, water often, and make sure of drainage holes; Maryland says gravel in the base does not help.

Squash vine borer, squash bugs and powdery mildew on zucchini

Squash vine borer. A zucchini that wilts suddenly, even in the morning, likely has a borer in its stem; look for holes with sawdust-like frass at the base (Minnesota). By Minnesota's timeline, the moths appear in late June or early July and lay eggs at the base of the plant; larvae hatch in about a week and feed inside the stem for 4 to 6 weeks. Timing advice depends on region:

• Minnesota. From late June, set out a yellow pan of soapy water and cover bush plants with floating row cover until about two weeks after the first moth (off at flowering), but not where squash grew last year, since moths emerging from that soil end up trapped under the cover. A second sowing in early July matures after the egg laying is over.
• South Carolina (Clemson). Plant early instead, because borers are a problem later in the season.
• Anywhere. At the first wilt, slit the stem, kill the larva and mound moist soil over the cut (Minnesota, Johnny's). Minnesota adds that Bt is useless once the larva is in the stem.

Squash bugs. These large, flat, grayish bugs suck sap and leave yellow spots that turn brown, worst on seedlings and flowering plants; females lay clusters of about 20 eggs under the leaves (Minnesota, Johnny's). Minnesota crushes the eggs, drops bugs into soapy water and traps them under boards overnight, and says insecticides are normally not needed.

Powdery mildew. From midsummer, older leaves grow white, powdery patches, favored by humid weather around 68 to 81 F and by crowded, shaded or overfed plants (Minnesota, Johnny's). Oregon State Extension suggests a resistant zucchini such as 'Payroll' or 'Sebring', drip watering, removing infected leaves, and squash in the same spot only once every 3 to 4 years, and says spraying is usually not warranted in a home garden.

What to plant with zucchini

Minnesota cites studies where a border of blue Hubbard squash can pull squash bugs from the crop, though that border still needs egg squashing or spraying. Research backs nasturtium beside squash too; it can help lower squash bug numbers (Minnesota), and Maryland says marigolds help cut squash bug and cucumber beetle damage. Evidence for each: our companion planting chart.

Seeds and supplies

Choose 'Costata Romanesco' for blossoms, a parthenocarpic variety for a bee-poor garden or one kept under cover, and a mildew-resistant zucchini where powdery mildew recurs; add a soil thermometer, floating row cover, shears and gloves, and a large pot with drainage holes for a patio.

What you'll need for zucchini

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  VIVOSUN 10 Gallon Grow Bags, 5-Pack

  A zucchini plant can grow in a container of at least 4 to 6 gallons, 8 to 12 inches deep (Maryland).

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  Corona FS 3214D ComfortGEL Micro Snips

  Shears and gloves for the harvest.

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Sources we used

All read in October 2026; where they disagree, each figure appears with its source.

• University of Minnesota Extension: "Growing summer squash and zucchini in home gardens", "Squash vine borers", "Squash bugs" and "Powdery mildew of cucurbits"
• "Illinois Extension: Summer Squash"
• University of Maryland Extension: "Growing Summer Squash (Zucchini) in a Home Garden" and "Types of Containers for Growing Vegetables"
• "Penn State Extension: Container Vegetable Gardening, Four Keys to Success"
• "Oregon State University Extension: How can I eradicate powdery mildew?"
• "NDSU Extension: Field to Fork, Summer Squash"
• "University of Saskatchewan: Pan fried squash blossoms"
• Companion pairs: "University of Minnesota Extension: Companion planting in home gardens" and "University of Maryland Extension: Vegetable Succession and Companion Planting"
• Johnny's Selected Seeds: "Zucchini Key Growing Information", its "Summer Squash Production" tech sheet and its 'Costata Romanesco' listing
• 'Costata Romanesco' listings from "Botanical Interests" and "Hudson Valley Seed Company"
• "NOAA NCEI: U.S. Climate Normals, 1991-2020", behind the zucchini calendar

Related guides

• Strawberries in pots and towers, another crop for a sunny container
• Building a raised garden bed; Penn State counts summer squash among the crops that thrive in one
• Squash and pumpkins, for winter squash, pumpkins and tromboncino
• How to grow melons, another vine crop that needs bees
• How to grow tomatoes, for the same warm beds
• How to grow okra, another crop to pick every day or two
• How to grow cucumbers, a vining cucurbit to grow alongside
• Cucurbits, the family overview with its shared vine borer and mildew notes

Frequently asked questions

How long does zucchini take to grow?

Roughly 50 to 65 days to the first harvest (Maryland from transplant; 52 to 60 from sowing for 'Costata Romanesco'), then usually 4 to 8 days from each flower to its fruit.

How far apart should zucchini plants be?

Most sources here say 18 to 36 inches between plants and 3 to 6 feet between rows; Minnesota alone thins to 8 to 12 inches.

Why are my zucchini flowers falling off with no fruit?

Early blooms are males, which simply fall off; females follow 1 to 2 weeks later, and if they drop too, bees may not be reaching them, so pollinate by hand.

Which zucchini flowers can you eat?

Both, but pick mostly males on the day they open and leave a few for pollination.

What size should you pick zucchini?

For most varieties, at about 6 to 8 inches long, no more than 2 inches across, checking every day or two.

Can you grow zucchini in a pot?

Maryland allows summer squash in pots of at least 4 to 6 gallons, 8 to 12 inches deep, but Penn State says zucchini does better in the ground.

Why did my zucchini plant wilt and die suddenly?

Most often a squash vine borer larva tunneling in the stem; look for holes with sawdust-like frass at the base. Next year, Minnesota sows a second crop in early July, after its moths have laid their eggs, while Clemson in South Carolina plants early instead.

How do you stop powdery mildew on zucchini?

Space plants for airflow, water at the base, remove infected leaves and grow a resistant variety (Minnesota, Oregon State); sprays are usually not warranted in a home garden.