A pile of harvested butternut squash, two cut open
How to grow

Winter squash

Warm-season and frost-tender. Start indoors 1 to 2 weeks before your last frost; plant out 2 to 3 weeks after your last frost; sow outdoors 2 to 3 weeks after your last frost. First harvest 80 to 100 days from sowing.

Photo: George Chernilevsky, Public domain, via Wikimedia Commons.

  • Full sun6–8 hours or more
  • 24–72 in apartRows 5–12 ft
  • 80–100 daysFrom sowing
  • Soil 65 °F +pH 6.0–6.5
  • 1–2 in a weekEven watering
  • Frost-tenderHurt by frost and cold wind

Your dates

Put in your ZIP code to see when to start, plant and harvest winter squash where you live, from your own frost dates.

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From seed to harvest

  1. SowSeed goes inWeek 0
  2. SproutFirst shoots showWeek 1–2
  3. VinesRunners spread outWeek 4–5
  4. FlowersFlowers openWeek 6–8
  5. Fruit setsSmall fruit formsWeek 7–9
  6. HarvestReady to pickWeek 11–15

How to plant and grow

  1. Sow in warm soil

    Sow seeds 3/4 to 1 inch deep after frost, once soil is at least 65 °F at 2 inches. Plant several seeds per hill and thin to the best two or three.

  2. Or start in pots

    For a head start, sow in pots about 4 weeks before planting out. Move them when they have 2 to 3 true leaves, keeping the root ball whole.

  3. Give vines room

    Vining types need 5 to 6 feet between hills and wide rows. Bush types fit about 3 feet apart in rows 5 feet apart.

  4. Water and mulch

    Give at least an inch of water a week. Mulch once the soil is above 75 °F to hold moisture and keep fruit clean.

  5. Scout for pests

    Watch for cucumber beetles on seedlings and squash bugs on vines. Act while their numbers are small.

  6. Harvest and cure

    Cut fruit with some stem once the rind is hard and colored, before a hard freeze. Cure in a warm spot, then store cool and dry.

Common problems

A cluster of squash bugs on a pumpkin
Photo: “Anasa tristis gathered on a pumpkin” by Ilona Loser, CC BY-SA 4.0, via Wikimedia Commons (cropped). The cropped version is shared under the same licence.

Squash bugPest

What you'll see: Flat gray-brown bugs and gray nymphs suck sap, leaving yellow spots that turn brown, and vines wilt. Bronze egg clusters sit under the leaves.

Prevent

  • Check leaf undersides each week from early summer and crush egg clusters.
  • Lay a board by the plants at night and destroy the bugs under it each morning.
  • Clear plant debris and mulch in fall.

Organic options

  • Hand-pick bugs and scrape off eggs.
  • OMRI Listed pyrethrins (without piperonyl butoxide) with diatomaceous earth around the base of the plants.

Conventional options

  • Esfenvalerate, permethrin or carbaryl, aimed at young nymphs soon after eggs hatch.

Bee caution: Don't spray open flowers. Spray in the late evening, when bees aren't flying.

A squash vine borer moth with an orange and black body
Photo: “Melittia cucurbitae P1440819a” by xpda, CC BY-SA 4.0, via Wikimedia Commons (cropped). The cropped version is shared under the same licence.

Squash vine borerPest

What you'll see: A vine wilts suddenly, and a hole near the base leaks orange, sawdust-like frass. A fat white larva is inside the stem.

Prevent

  • Cover vines with row cover when they start to run, and remove it at flowering.
  • Do not use row cover where squash grew last year; borers spend the winter in that soil.
  • Grow butternut squash, which is hit less often.
  • Pull and destroy vines killed by borers.

Organic options

  • Slit the stem lengthwise above the frass, remove the larva, and cover the cut with moist soil.
  • Bt sprays do not reach larvae inside the stem.

Conventional options

  • Carbaryl, permethrin, bifenthrin or esfenvalerate on the stem bases, starting when adults first appear.

Bee caution: Don't spray open flowers. Spray in the late evening, when bees aren't flying.

A striped cucumber beetle, yellow with black stripes
Photo: “Acalymma vittatum P1310371a” by xpda, CC BY-SA 4.0, via Wikimedia Commons (cropped). The cropped version is shared under the same licence.

Cucumber beetlesPest

What you'll see: Yellow beetles with black stripes or spots chew seedlings, leaves and flowers. They spread bacterial wilt, which kills cucumbers and melons.

Prevent

  • Cover seedlings with row cover and seal the edges; remove it at flowering so bees can reach the blooms.
  • Clear weeds and plant debris where adults spend the winter.
  • Mulch with straw around established plants.

Organic options

  • Knock beetles into soapy water on small plantings.
  • Kaolin clay on the leaves deters feeding but does not kill beetles; apply it before damage builds.

Conventional options

  • Several garden insecticides are labeled for cucumber beetles; check the crop is listed. Spray early or late in the day to spare bees.
A squash leaf coated with white powdery mildew
Photo: “Powdery mildew 9” by Dmitry Brant, CC BY-SA 4.0, via Wikimedia Commons (cropped). The cropped version is shared under the same licence.

Powdery mildewDisease

What you'll see: White, powdery patches on the tops of leaves and on stems. Leaves yellow and dry, and fruit may ripen poorly.

Prevent

  • Grow resistant varieties.
  • Give plants sun and space for air flow.
  • Remove badly infected leaves, and clear debris after harvest.

Organic options

  • Sulfur or potassium bicarbonate, from the first spots. Sulfur can burn some vine crops in heat, and never use it near an oil spray.
  • Neem oil. Look for OMRI Listed products.

Conventional options

  • Myclobutanil or propiconazole, if the crop is on the label.

Bee caution: Don't spray open flowers. Spray in the late evening, when bees aren't flying.

A winter squash fruit pitted with sunken anthracnose spots
Photo: Scot Nelson from Honolulu, USA, CC0, via Wikimedia Commons.

AnthracnoseDisease

What you'll see: Sunken spots: tan to dark brown on cucumber and melon leaves and fruit, small purple-edged spots on raspberry canes. In wet weather the spots can ooze pink spore masses.

Prevent

  • Grow vine crops in a new bed each year and clear plant debris after harvest.
  • Water at the base, not overhead, so leaves stay dry.
  • Thin raspberry canes in winter for air flow and destroy the prunings.

Organic options

  • Remove spotted leaves, fruit and canes.
  • Copper fungicide, started when spots first appear in wet weather. Look for OMRI Listed products.

Conventional options

  • Chlorothalonil on vine crops, if the crop is on the label. It protects leaves best before the disease takes hold.

Bee caution: Don't spray open flowers. Spray in the late evening, when bees aren't flying.

Read and follow the product label: it is the law. It sets the rate, the crops it is for, and the days between spraying and picking. Products registered vary by state; for organic growing, look for products allowed under the USDA National Organic Program (OMRI Listed). We name active ingredients, not brands or rates.

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Sources

Planting dates and growing facts checked against these university extension and USDA pages:

Growth-stage drawings: TallyTill.

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