Overwintering crops
Garlic, shallots and winter onions go in the ground in fall, sleep under mulch all winter and are harvested the next summer.
Some crops grow across the new year. Garlic is the classic one: in northern Wisconsin you plant cloves in mid-October, they put down roots before the ground freezes, sit dormant all winter, sprout in spring, and you dig the bulbs in late July or August.
Turning it on
Seed packets have an Overwinters box. It is checked for you on garlic, shallots and winter onions (Egyptian walking onions), which are well-known fall-planted crops. Check it for anything else you plant in fall for next year, or uncheck it if you grow spring garlic.
How the dates are worked out
- Plant: a two-week window that opens on your first fall frost date. With an October 15 first frost, plant October 15 to October 29. The ground usually freezes around 6 weeks after first frost, so the window closes about 4 weeks before the freeze, which gives roots time to grow. Heirloom uses your own frost dates if you set them.
- Mulch: when the ground is about to freeze, cover with 4 to 6 inches of straw or shredded leaves.
- Spring check: about 3 weeks before your last spring frost, pull the mulch back as the shoots come up, and weed.
- Scapes (hardneck garlic): about 3 weeks before harvest, snap off the curly flower stalks. Softneck garlic doesn't make them.
- Harvest: the next summer, counted from next spring's last frost. Dig when the lower leaves turn brown. Shallots come a little earlier than garlic.
Already planted? Mark it as planted with the date, and Heirloom uses your date instead.
On the timeline
An overwintering crop gets one bar that wraps around the year. The fall part is at the end of the year: a dashed Plant window, then rooting in until the ground freezes. A pale striped Dormant stretch covers winter, and the spring growth and harvest are at the start of the year. Small arrows at both edges show it carries on across the new year. Hover a part to see the dates, for example Continues from Oct.
Seed cards, reminders and the bed planner
- Seed cards show both years: the fall planting window (for example Plant Oct 15 to Oct 29), then next summer's harvest, plus the mulch, uncover and scape dates.
- Reminders send Plant (when the window opens), Last call (when it closes), Mulch, Uncover, Cut scapes and Harvest opens on those dates.
- Bed planner: the crop holds its spot from fall planting until next summer's harvest. If you plan a crop to follow it in the same spot (succession), it starts after the harvest, and anything planned sooner shows as overlapping.