Timing Your Planting Dates for Earliest Spring Harvest
Overwintering entails establishing very young plants that can survive the winter and resume growth extra early the following spring. Once day length increases to 10 hours, these plantings will grow rapidly. Keep in mind that wide fluctuations in late-winter temperatures can sometimes cause overwintered crops to bolt before they reach a harvestable stage.
The most calculated approach to scheduling seeding for overwintered crops involves seeding in the late fall, so that germination and the first stages of growth occur before the plant goes dormant during the Persephone period. Growth will begin again when days begin to lengthen.
Another overwintering method involves sowing just before the ground freezes, so that germination occurs after deep winter, as day length increases and temperatures warm. This method can result in a lot of dead seed, however, if conditions do not pan out. (There is a risk that a higher percentage of seeds will rot in the soil during cold, wet conditions.)
An additional strategy is to seed just as the ground begins to thaw, or just as the Persephone period is ending (so technically, this is not overwintering); only the top inch or two of soil needs to be thawed in order to plant the seed.
Scheduling Guidelines for Planting Crops for Overwintering
Ten hours of daylight
Use our clickable Overwintering Planting Chart to time your planting dates for earliest spring vegetable harvest.
Keep in mind that the planting dates are back-scheduled from the last 10-hour day at your latitude.
The number of weeks before the Persephone period is calculated for each listed crop.
The vegetable crops are grouped, as outlined in the chart key, to reflect their reliability for overwintering success.
Scheduling Guidelines for Overwintering Flowers
After several years of research and trialing, we are pleased to share the results of our overwinter flower trials. Along with the Winter Growing Guide information here in Johnny's Vegetable Grower's Library — which pertains primarily to vegetable crops — we now offer introductory methods and recommendations, results by crop (worksheet), and a seeding date calculator (worksheet) for overwintering flowers in our Flower Grower's Library.
- Intro to Winter Growing
- Winter High Tunnel Scheduling Guidelines
- Winter-Harvest Crops • Planting Chart
- Winter Production in the High Tunnel
- Overwintering Scheduling Guidelines
- Overwintering Crops • Planting Chart
- Protection Methods for Overwintering in Low Tunnels
- Focus on Crops & Varieties for Winter Growing
- Overwintering Onions from Seed