Zucchini and Squash planting dates by zone

Zucchini, yellow squash and pattypan

UF/IFAS Gardening Solutions says zucchini, yellow squash, crookneck and pattypan are not just the same genus but the same species, Cucurbita pepo, all grown for their thin, edible skin. University of Illinois Extension says summer squash differs from winter squash in being picked before the rind hardens, and grows on bush plants that do not spread like winter squash and pumpkin.

Illinois sorts the shapes into scallop or pattypan, flat with scalloped edges; crookneck and straightneck, thinner at the stem end and usually yellow; and the cylindrical Italian marrows such as zucchini, cocozelle and Caserta. Clemson’s Home & Garden Information Center lists cultivars for each, from ‘Black Beauty’, a zucchini introduced in the 1920s, to ‘Sunburst’ scallop, and says some varieties are bush types useful in small gardens.

You need few plants. Illinois says the average family needs only one or two of each variety, and UF/IFAS that four to six plants generally feed a family of four.

Sowing and planting

University of Minnesota Extension prefers direct seeding: squash seed will not germinate in cold soil, and plants started indoors and set into cold soil, or damaged in transplanting, often fail to grow. It sows after the last frost date once the soil has warmed, which is late May in most of Minnesota and early June in the north. Clemson also waits until after the last chance of frost and the soil has warmed. The table dates outdoor sowing 1 week after each zone’s median last spring freeze, the offset our seed-starting tool uses.

Clemson and UF/IFAS both plant either seed or transplants; UF/IFAS says to use containerized transplants with mature roots. The table’s indoor date is 3 weeks before the median last freeze and its set-out date 1 week after.

Spacing varies by source. Clemson sows seed one-half inch deep and 4 to 6 inches apart in rows 3 feet apart, thinning to 12 to 15 inches, or plants hills 3 to 4 feet apart in rows 4 to 6 feet apart. Illinois sows two or three seeds 24 to 36 inches apart, covered one inch deep, and thins to one strong plant. UF/IFAS gives each plant 2 feet in rows 3 feet apart, seed 1 to 1.5 inches deep. Minnesota thins to 8 to 12 inches and plants bush types in rows or hills two to three feet apart.

For an earlier crop, Clemson and Minnesota use black plastic mulch to warm the soil and a row cover over the seedlings. Minnesota says the cover keeps bees off the flowers, so remove it once flowering begins; Clemson uses black plastic for the spring crop only, and paints it white for a fall crop.

Water, mulch and feeding

Minnesota gives vine crops about one inch of water a week, soaking the soil with a drip or soaker hose and keeping the leaves dry. Clemson waters in the morning to moisten the soil 6 inches deep, and says the critical period is fruit set and development.

Clemson says too much nitrogen gives vines at the expense of fruit, and side-dresses before the vines start to develop; Minnesota side-dresses when the plants begin to spread. Both aim for a soil pH of 6.0 to 6.5.

Clemson says blossom-end rot, a dark, dry rot at the blossom end of the fruit, comes from a lack of calcium in the developing fruit, and prevents it with a soil test and lime, 2 to 3 inches of mulch, steady water in dry spells and no excess nitrogen or potash. Minnesota waits to put down straw or compost mulch until the soil is fully warm.

Southern timing

Clemson’s planting table gives the South Carolina Piedmont April 15 to July 31 in spring and July 15 to August 15 in fall, and the Coastal Plain March 15 to July 31 and August 1 to 31. It says to plant early, because squash vine borers and pickleworms are problems later in the season.

UF/IFAS says that despite the name, summer squash does not really grow in Florida’s summer heat: North Florida plants from February to April and in August and September, Central Florida from February to May and again in August and September, and South Florida from August to March. Texas A&M AgriLife’s home vegetable gardening guide sows summer squash 1 to 4 weeks after the frost-free date in spring and 12 to 15 weeks before the first freeze in fall.

Illinois plants any time after the danger of frost has passed until midsummer, and says some gardeners make two main plantings, one for early summer and one for late summer and fall. Minnesota sows part of the planting first and the rest three weeks later for a longer harvest. The table’s last sowing counts back 55 days from each zone’s median first fall freeze, our crop table’s days to harvest with no frost to spare.

Harvest

Clemson says summer squash can be picked about 55 days after planting, and UF/IFAS gives 40 to 50 days. Illinois says the fruit is usually ready 4 to 8 days after flowering, especially in hot weather, so go over the plants every 1 or 2 days.

Pick small. Illinois picks most long varieties at 2 inches or less across and 6 to 8 inches long, and pattypans at 3 to 4 inches across; Clemson picks zucchini at 7 to 8 inches, crooknecks and straightnecks at 1½ to 2 inches across and scallops at 3 to 4 inches. Clemson and Minnesota say large fruit left on the plant holds back new fruit.

Cut, do not pull. Illinois and Clemson use a sharp knife or pruners, and UF/IFAS leaves an inch or two of stem on the fruit. Illinois and UF/IFAS say the stems and leafstalks are prickly, so wear gloves. Minnesota does not pick when the vines are wet, which spreads disease.

Common problems

Squash vine borers, Minnesota says, burrow into the crown and make the whole plant wilt. Illinois says the adult is a clear-winged moth that lays eggs at the base of the plant, the larvae tunnel into the stem, and the infestation is worse in an extended dry spell in early summer; the pest overwinters in the soil near the old plants. Clemson says to plant early to stay ahead of vine borers and pickleworms.

Squash bugs gather in groups and give leaves a ragged look, Minnesota says; Illinois says they build up through late summer. Clemson describes the adults as dark gray to dark brown sap-feeders that lay eggs in a V between the leaf veins. Cucumber beetles feed on seedlings, vines and fruit, Illinois says.

Minnesota says the first flowers to drop are male and that is normal, and the first flush of fruit is often poorly pollinated until the bees find the planting. Clemson says poor pollination gives no fruit or badly shaped fruit, and to spray only late in the evening to spare the bees. Powdery mildew is common on the leaves, Clemson and Minnesota say; UF/IFAS warns that zucchini leaves have natural silvery splotches that are often mistaken for mildew.

Common mistakes

• Planting more than you can use. Illinois says one or two plants of each variety is enough for most families.
• Letting the fruit grow large. Illinois and Clemson say oversized squash holds back new fruit.
• Planting late in the South. Clemson says vine borers and pickleworms are worse later in the season.
• Leaving row cover on through flowering. Minnesota says bees must reach the flowers.
• Spraying while bees are working. Clemson sprays only late in the evening.
• Treating zucchini’s silver leaf markings as mildew. UF/IFAS says they are natural.

We found no summer squash source for Louisiana, Alabama or Mississippi that we read for this page. The Southern timing here is Clemson’s, UF/IFAS’s and Texas A&M AgriLife’s.

Questions

When should I plant zucchini?

University of Minnesota Extension sows squash after the last frost date once the soil has warmed, and Clemson after the last chance of frost. The table on this page gives a date 1 week after each zone’s median last spring freeze, from NOAA records.

How big should zucchini be when you pick it?

University of Illinois Extension picks most long summer squash at 6 to 8 inches long and 2 inches or less across, and Clemson picks zucchini at 7 to 8 inches. Both say smaller fruit is more tender.

Why is my squash plant wilting suddenly?

Often squash vine borers. Minnesota and Illinois say the larvae tunnel into the base of the stem and the plant wilts, sometimes seemingly overnight. Clemson says planting early helps avoid them.

Why are my zucchini rotting at the end?

Clemson calls it blossom-end rot, caused by a lack of calcium in the developing fruit, and prevents it with a soil test and lime, mulch, steady watering and no excess nitrogen or potash.

Are zucchini and yellow squash the same plant?

Yes, botanically. UF/IFAS says zucchini, yellow squash, crookneck and pattypan are all the same species, Cucurbita pepo, and our crop table gives them the same timing.

Sources

Freeze dates on this page are NOAA 1991–2020 Climate Normals, for every station the ZIP codes in each zone cite. Zones are the USDA Plant Hardiness Zone Map, 2023. The planting rules are named beside the table. Growing advice is quoted from the extension publications below, each written for its own area.

• University of Minnesota Extension, Growing summer squash and zucchini in home gardens , by Marissa Schuh, Vincent A. Fritz and Carl J. Rosen (Reviewed 2024). Written for: Minnesota (USDA zones 3a–5a).
• University of Illinois Extension, Summer Squash (Home Vegetable Gardening) . Written for: Illinois (USDA zones 5a–7a).
• Clemson Cooperative Extension, Home & Garden Information Center, Summer Squash (HGIC 1321) (Updated February 3, 2023). Written for: South Carolina (USDA zones 8a–9b).
• UF/IFAS Gardening Solutions, Summer Squash (Accessed October 2026). Written for: Florida (USDA zones 8b–11b).
• Texas A&M AgriLife Extension, Texas Home Vegetable Gardening Guide (EHT-077) , by Joseph Masabni (June 2014). Written for: Texas (USDA zones 6b–10b).

How we write our guides

Published October 27, 2026