When to Start Winter Sowing by Zone
Winter sowing dates by zone, counted back from typical last spring frost. Perennials that need cold go first, hardy flowers and cool crops next, tomatoes...
Published by ThriveThyme
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When to Start Winter Sowing by Zone
Start winter sowing in December at the earliest. Sow in four waves, counted back from your last spring frost:
- Perennials and natives that need cold: 20 to 10 weeks before last frost.
- Hardy annual flowers and self-sowers: 14 to 8 weeks before last frost.
- Cool-season vegetables and herbs: 10 to 4 weeks before last frost.
- Tender flowers and warm-season crops: 6 to 3 weeks before last frost.
The Winter Sowing Desk turns this into dates for your zone or your own My Garden frost date.
Dates by Zone for Spring 2027
Dates use typical zone last frost dates. Your yard can run a week or two either way.
| Zone | Last frost | Need cold | Hardy flowers | Cool crops | Tender crops |
|---|---|---|---|---|---|
| 3 | May 20 | Dec 31 to Mar 11 | Feb 11 to Mar 25 | Mar 11 to Apr 22 | Apr 8 to Apr 29 |
| 4 | May 10 | Dec 21 to Mar 1 | Feb 1 to Mar 15 | Mar 1 to Apr 12 | Mar 29 to Apr 19 |
| 5 | Apr 30 | Dec 11 to Feb 19 | Jan 22 to Mar 5 | Feb 19 to Apr 2 | Mar 19 to Apr 9 |
| 6 | Apr 20 | Dec 1 to Feb 9 | Jan 12 to Feb 23 | Feb 9 to Mar 23 | Mar 9 to Mar 30 |
| 7 | Apr 10 | Dec 1 to Jan 30 | Jan 2 to Feb 13 | Jan 30 to Mar 13 | Feb 27 to Mar 20 |
| 8 | Mar 25 | Dec 1 to Jan 14 | Dec 17 to Jan 28 | Jan 14 to Feb 25 | Feb 11 to Mar 4 |
| 9 | Feb 25 | Dec 1 to Dec 17 | Dec 1 to Dec 31 | Dec 17 to Jan 28 | Jan 14 to Feb 4 |
Why Not Earlier
Jugs set out in October or November can sprout during a warm spell, then freeze. December is the earliest start in extension guidance. Penn State Extension gives December to March for perennials and hardy annuals, and March or April for tender crops in Pennsylvania.
Why Perennials Go First
Many perennial and native seeds need 4 to 12 weeks of cold, moist weather before they sprout. Sowing them early gives winter time to do that. Sown late, they may not sprout until a second spring. See which seeds need cold stratification.
Why Tomatoes Go Last
Tender crops do not need cold. They sprout only when days warm and die in a hard freeze if they come up early. Sow them 6 to 3 weeks before last frost and plant out after last frost, once nights stay above about 50F.
Zones 8 to 10
- Zone 8 and 9: the cold window is short. For seeds that need 30 days or more of cold, sow in early December or stratify them in the fridge first.
- Zone 10 and warmer rarely freeze. Jugs will not chill seed. Direct sow cool crops in fall and winter, and fridge-stratify perennial seed.
Cold Zones
In zones 3 and 4, a long, cold spring can hold jug seed until May. South Dakota State University Extension notes that indoor starts can beat winter-sown plants in that case. Use jugs for perennials and hardy crops, and keep peppers under lights indoors with the seed-start calendar.
Set your own last frost in My Garden, then open the Winter Sowing Desk for your jug plan.