Winter Growing Guide
Winter Growing Guide
Winter-Harvest vs. Overwintering
At about 44°N latitude, the Persephone period starts in early November
and lasts until early February, when days at that latitude are back to 10 hours long.
Falling temperatures and shrinking days don't have to end your harvest. With more growers adding high and low tunnels and selling at winter markets, a common question is: What can I plant for a winter harvest, and when?
Growing saleable crops in winter means learning the right planting windows for where you are. This guide is meant as a starting point, mainly for unheated tunnels. Use the charts and guidelines here and adjust methods and timing to your region and practices. Keep records so you can see what works best and build on it.
First, it helps to separate the two main winter strategies: crops you harvest during winter, and crops you leave in place through winter for an early spring harvest.
- Winter-Harvest Crops go in during late summer or early fall, mostly in high tunnels, and are harvested through the winter.
- Overwintered Crops go in during fall or winter, often in the field or under low tunnels, and stay put for the earliest possible spring harvest.
In your system the two may blur together, but thinking of them separately makes it easier to build a production timeline. The methods are flexible and overlap a lot, and many growers mix them with succession planting to produce in all four seasons.
Winter Harvest Fundamentals
The Persephone Period: 10 hours of day light
For winter-harvest crops, the key date is when day length falls to 10 hours on its way to the winter solstice. This darkest stretch of the year, which Eliot Coleman calls the Persephone period , is when most crops nearly stop growing.
(Look up exact dates for your area with an app or website such as Sundial • Solar & Lunar Times or SunriseSunset.)
Aim to sow so your crops are about 75% grown when the Persephone period begins.
They won't grow much after that, until days are back above 10 hours, but you can keep harvesting them as long as they hold.
Good scheduling lets you control growth step by step: make at least two or three sowings 7–10 days apart, then tighten the gap to 2–5 days as the Persephone period gets close. Staggered sowings mature at different times and stretch the harvest. You might sow on September 20, September 27 and October 1, for example. Well-timed successions give a smooth handoff from one harvest to the next and a steady supply all winter. Several sowings also show you the best dates for each crop (worth writing down) and spread the risk if the weather turns bad.
The Winter Harvest Handbook by Eliot Coleman is a thorough guide to growing crops all winter.
Two ways to get plants ready for the darkest days in high or low tunnels
- Transplant crops such as spinach that are usually direct-sown. Grow seedlings to transplant size somewhere else, then set them into the high tunnel once the summer crops are cleared out.
- Plant hardy crops outdoors in late summer, then move a portable tunnel over them or build a caterpillar tunnel over the planting as winter approaches.
Squeeze in even one more crop
Plan ahead for beds that will open up in late winter after your winter crops are harvested.
- Some crops, such as lettuce, are done by early to midwinter.
- Others, such as mustards, bolt as the Persephone period ends and are finished then. Toward the end of the Persephone period you can replace them with direct-sown spinach or brassicas, for example.
These late-winter sowings are ready in early spring, often well ahead of the same crop grown outdoors.
Overwintering Fundamentals
Winter growing works at any scale. In The Year Round Vegetable Gardener, Niki Jabbour explains how to harvest all year in a home garden.
Overwintering means establishing young plants that can make it through winter and start growing again very early in spring. Once days reach 10 hours, they grow fast.
Big temperature swings in late winter can make overwintered crops bolt before they're ready to harvest. Choosing varieties with better bolt resistance helps. (See our Good for Overwintering category, where varieties are chosen with this in mind.)
The most deliberate way to time overwintered crops is to sow between late summer and late fall, depending on the crop. (Check the Overwinter Planting Chart for each crop's planting window.) With the right timing, seeds sprout and make their first growth before the plants go dormant for the Persephone period, then start growing again as days get longer.
Another approach is to sow just before the ground freezes so seeds germinate after the depth of winter, as days lengthen and soil warms. If conditions don't cooperate, though, a lot of seed can be lost, since more seeds may rot in cold, wet soil.
You can also sow as soon as the ground starts to thaw or the Persephone period ends (strictly speaking, not overwintering). This works well for direct-sown spinach and brassicas, and only the top inch or two of soil needs to be thawed.
Scheduling Guidelines
The charts give planting dates by crop for winter harvest and for overwintering. Remember that the dates are counted from the Persephone period at your latitude.
Next
- Winter growing guide, part 2: growing in the high tunnel through winter
- Winter growing guide, part 3: low tunnels for overwintering
- Winter growing guide, part 4: planting dates for winter harvest
- Winter growing guide, part 5: planting dates for overwintering
- Winter growing guide, part 6: crops and varieties for winter
Overwintering Flowers
The same overwintering ideas work for cold-hardy annual flowers and give an early cutting season. Our flower trial results are in these resources:
- Overwintering flowers guide • Article
- Trial results by crop • XLSX spreadsheet
- Seeding date calculator • XLSX spreadsheet
- Tutorials and webinar • Written guides
