Choose season-extension crops by how they react to cold and short days: frost-tolerant greens and roots stand through winter and can be picked as needed, biennials can be held in the ground to flower and set seed in spring, and tender crops can be started under cover early and set out after the last frost. Find your own last and first frost dates from several years of records before scheduling anything, because no date is universal. Sow the winter crops while days are still long, since plants grow very little once daylight falls under about 10 hours.
Season extension crops are the vegetables chosen and timed to produce earlier in spring and later into autumn and winter than the ordinary growing season allows.
Three Kinds Of Crop Fit Three Jobs
- Hardy crops that stand through winter — spinach, kale, mâche, claytonia, leeks, parsnips and carrots under mulch. See Cold-Hardy Greens and Roots.
- Biennials held over — plants that grow one season and flower the next, which you can overwinter for food or seed. See Overwintering Biennials.
- Tender crops started early — tomatoes, peppers and others begun indoors or under cover and moved out after the last frost. See Spring-Started Transplants.
Find Your Own Frost Dates And Day Length
This corpus has no location, so it cannot give your last-frost date, first-frost date or day length. Find them from your own records.
Step 1: Record the daily minimum temperature with a thermometer in open air, shaded, at about 1.5 m height.
Step 2: Note the last spring date and first autumn date on which the minimum reached 0°C (a light frost), each year. After several years you will see how much the dates move.
Step 3: Choose your risk. Choose a planting date after which frost has been rare in your records, and accept that an unusual year will break it. Frost-tender crops need a later date than hardy ones.
Step 4: Find day length. Note sunrise and sunset through the year, and mark the dates on which daylight falls below and rises above 10 hours. The carrier says plants grow very little under 10 hours of day; between those dates, winter crops mostly hold and do not grow.
Step 5: Count back from the dates to schedule sowing: see Staggered Sowing Schedules.
Common Mistakes
- Copying a sowing calendar from another climate — the dates do not transfer.
- Sowing hardy crops too late — they must reach near-maturity before the short days.
- Choosing by taste alone — a crop that dislikes cold will not stand through winter.
What’s Next
- Learn next: Cold-Hardy Greens and Roots — the crops that stand
- Combine with: Succession Planting — spacing the sowings