When to Harvest Winter Squash
How to tell squash is ripe, why colour can fool you, and which types need curing.
When to harvest winter squash is later than the colour suggests. The University of Massachusetts says squash is mature when its seeds are completely filled, usually 50 to 55 days after the fruit sets, and that in many varieties that is weeks after the fruit turns its finished colour.
The other deadline is cold. The same source warns of chilling injury below 10°C (50°F), and the University of Minnesota says to harvest when the shells are hard and before a frost.
Winter squash harvest at a glance: Harvest when the rind is hard and the type-specific sign shows (acorn: dark orange ground spot; butternut: about two weeks after it turns tan; hubbard and buttercup: dry, corky stem), and before frost. Handle gently. Cure butternut and hubbard types; do not cure acorn. Store at 10–15°C, dry.
Harvesting root crops too? See When to Harvest Carrots for the carrot harvest signals.
Ripeness by Type
| Type | Examples | Ready when | Cure? |
|---|---|---|---|
| Cucurbita pepo | Acorn, delicata, pie pumpkins | Ground spot dark orange (acorn); skin fully orange (pie pumpkin) | No; curing shortens storage |
| Cucurbita moschata | Butternut | About two weeks after it turns tan | Yes, or store 1–2 months before eating |
| Cucurbita maxima | Hubbard, buttercup, kabocha | Stem dry and corky | Yes, or store 1–2 months before eating |
From the University of Massachusetts. It notes acorn squash turns dark green weeks before it is ripe, which is why so many are picked too early.
Beat the Frost
The University of Massachusetts says chilling injury builds below 10°C, and chilled fruit does not store well. The University of Minnesota says to harvest before a frost. In much of Canada that means watching the forecast in September:
| City | Zone | Average First Fall Frost |
|---|---|---|
| Vancouver | 8b | Nov 30 |
| Kelowna | 6b | Oct 15 |
| Calgary | 3b | Sep 21 |
| Edmonton | 4a | Sep 23 |
| Saskatoon | 3a | Sep 12 |
| Winnipeg | 3a | Sep 20 |
| Thunder Bay | 3b | Sep 20 |
| Ottawa | 5a | Oct 12 |
| Toronto | 6b | Nov 1 |
| Montréal | 5b | Oct 7 |
| Quebec City | 5a | Sep 28 |
| Fredericton | 5a | Sep 26 |
| Halifax | 6a | Oct 18 |
| St. John’s | 5b | Oct 13 |
Frost dates from this site’s data.
Handle Gently
The University of Massachusetts says the rind bruises and punctures easily, and decay follows any wound. Move squash gently, and keep fruit from knocking together; it notes butternut stems can puncture neighbouring fruit.
Curing and Storage
Curing, according to the University of Massachusetts, means 5 to 10 days at 27–29°C (80–85°F) and 80–85% humidity right after harvest. It hardens the skin and speeds the change from starch to sugar in butternut and hubbard types. Acorn and delicata should not be cured.
Store at 10–15°C (50–60°F) and 50–70% humidity: cool, dry and well ventilated, off the floor. The same source gives 2 to 3 months for acorn types and 4 to 6 months for butternut and hubbard types. A cool spare room or the coolest part of a basement often works.
A Prairie Note on Frost
The University of Saskatchewan treats winter squash as a long-season crop and says to harvest as late in the fall as you can. Its figures: the vines freeze at 0°C, but mature fruit can take −2 to −3°C. That is a little more frost than the sources above allow, so if you leave squash out late, bring it in before a forecast colder than −2°C.
Cut squash from the vine with a sharp knife or pruners, leaving at least 3 cm of stem to avoid stem-end rot, and store it in moderately warm, dry conditions, about 10°C.
Frequently Asked Questions
How do I know when winter squash is ripe?
The rind is hard and the type-specific sign shows: a dark orange ground spot on acorn, about two weeks past turning tan for butternut, and a dry, corky stem on hubbard and buttercup.
Can winter squash stay out through frost?
No. The University of Massachusetts warns of chilling injury below 10°C, and the University of Minnesota says to harvest before a frost.
Do I need to cure winter squash?
Butternut and hubbard types benefit from curing, or from a month or two of storage before eating. Acorn and delicata should not be cured.
How do I cure butternut or hubbard squash?
The University of Massachusetts gives 5 to 10 days at 27 to 29°C and 80 to 85% humidity right after harvest. A warm, airy room indoors can work.
How do I store winter squash?
Cool and dry, at 10 to 15°C and 50 to 70% humidity, off the floor and with good air movement.
How long does winter squash keep?
About 2 to 3 months for acorn types and 4 to 6 months for butternut and hubbard types, according to the University of Massachusetts.
Sources
- University of Massachusetts Amherst Extension — Pumpkin and Winter Squash Harvest, Curing, and Storage
- University of Minnesota Extension — Harvesting and storing home garden vegetables
- University of Massachusetts Amherst Extension — Optimal Storage Conditions and Ethylene Sensitivity of Fall Storage Crops
- Environment and Climate Change Canada — Canadian Climate Normals (the frost dates in the tables, read from this site’s frost data)
- University of Saskatchewan, Gardening at USask — Winter squash