The Commercial Grower's Seasonal Seedling Calendar by USDA Zone

Timing is everything in propagation. Start too early and seedlings become root-bound in their trays. Start too late and you miss your market window. This calendar helps commercial and serious hobby growers match their sowing schedule to their USDA hardiness zone.

Understanding USDA Hardiness Zones

The USDA Plant Hardiness Zone Map divides North America into 13 zones based on average annual minimum winter temperatures. Each zone is a 10°F (5.6°C) band, subdivided into "a" (colder) and "b" (warmer) halves.

For commercial seedling production, the critical dates are your last spring frost and first fall frost. These define your outdoor growing season and determine when transplants need to be ready.

Master Sowing Calendar

Use the following table as your planning base. Dates shown are weeks before the last expected frost for spring crops, or weeks before first fall frost for fall crops.