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When to Plant Squash

Dates to sow squash outdoors for your ZIP code or zone.

Tomato and pepper seedlings in trays under an LED grow light

Squash planting dates by zone

At the average last frost date for each USDA half-zone (the median across its ZIP codes, NOAA 1991 to 2020 normals). Enter your ZIP code below for your own dates.

ZoneLast frostSow outdoors
3aMay 28May 28
3bMay 17May 17
4aMay 13May 13
4bMay 8May 8
5aMay 4May 4
5bMay 1May 1
6aApr 29Apr 29
6bApr 23Apr 23
7aApr 16Apr 16
7bApr 6Apr 6
8aMar 29Mar 29
8bMar 18Mar 18
9aMar 3Mar 3
9bFeb 2Feb 2
10aJan 16Jan 16
10brareby season
Your location

Zone medians. Your ZIP code gives the dates of your nearest weather station.

Frost risk

Half of years still get a frost after the spring date, and half get the first fall frost before the fall date.

Frost dates at three risk levels
AverageSaferSafest
Last spring frostApr 23Apr 30May 9
First fall frostOct 22Oct 16Oct 7
Crops (1 selected)

First job: sow seeds outdoors

Apr 23squash

Average frost dates: last Apr 23, first Oct 22 (zone 6b).
Season
Spring seed starting schedule
CropSow outdoorsNotes
SquashTenderApr 23Sow outdoors at last frost. Sprouts in 3 to 12 days, best at 70 to 95°F soil.

How to start seeds indoors

Light
Give seedlings 14 to 18 hours of light a day on a timer, with fluorescent or LED fixtures 2 to 6 in above the leaves. Raise the lights as the plants grow.
Clemson HGIC: 16 to 18 hours, tubes 2 to 4 in above. UMD Extension: 14 to 16 hours, 2 to 6 in.
Seed starting mix
Use a sterile, soilless mix, never garden soil. To mix your own, combine equal parts by volume of fine pine bark, sphagnum peat moss and perlite.
NC State Extension Gardener Handbook; Clemson HGIC.
Sowing and warmth
Sow two or three seeds per cell and keep the strongest seedling. A mix temperature of 65 to 75°F germinates most vegetables; after they sprout, 55 to 60°F nights and 65 to 70°F days keep them stocky.
UMD Extension.
Potting up
Move seedlings into larger pots shortly after the first true leaves appear, while they are small and recover quickly.
UMD Extension; Clemson HGIC (one or two sets of true leaves).
Hardening off
Start two to three weeks before transplanting, once plants are about 3 in tall: set them outdoors by day, bring them in before sundown, and give them more direct sun each day. Skip days below 45°F or with strong wind.
Clemson HGIC: 2 to 3 weeks. NC State: at least 2 weeks, not below 45°F.

When to plant squash

Squash seed goes straight into the garden on the average last frost date, according to Colorado State University Extension, and Utah State University Extension adds the soil test: plant when the soil is 65°F or all frost danger has passed. The table above lists that date for every USDA zone, and the planner below it gives your own from your ZIP code.

Sow outdoors = average last frost date, once the soil reaches 65°F

Example dates by zone

At the median last frost for each half-zone (NOAA 1991 to 2020 normals):

ZoneSow outdoorsAverage first fall frostDays of season left
4bMay 8Oct 1146
5bMay 1Oct 10162
7aApr 16Oct 25192
9aMar 3Nov 25267

Colorado State gives squash 50 to 100 days from seed: the short end is summer squash, the long end winter squash. Even zone 4b has 146 days between the average last and first frosts, so both kinds fit a single spring sowing at average dates. In colder ZIP codes the planner flags it when the slow end no longer fits.

Summer and winter squash on the calendar

Both kinds are sown on the same day, but they finish far apart:

  • Summer squash comes into flower 35 to 45 days after sowing, and Utah State picks the fruit 3 to 5 days after the flower opens. A May 1 sowing in zone 5b flowers around Jun 5 to Jun 15, with the first fruit a few days later.
  • Winter squash needs about 100 days, and Utah State says the fruit takes 45 to 55 days to mature after flowering. Harvest with the stem attached, and store it cool (50 to 55°F) and dry.

In a short season, sow winter squash at the start of the window. Summer squash, at about 50 days, can also be sown later in the season.

Seed, soil and transplants

Oregon State University Extension's germination table puts the minimum soil temperature for squash at 60°F and the best range at 70 to 95°F. Seed usually comes up in 3 to 12 days in warm soil. Sow 4 to 6 seeds per mound, 1 to 1½ inches deep, and thin to two plants once they have two leaves (Utah State).

The planner shows outdoor sowing only, because the sources above sow squash direct. If you do grow transplants, Utah State sets them out with 2 to 3 mature leaves and a well developed root system, after the same frost and soil conditions.

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