When to Plant Vegetable Seeds

Cool-season vegetables work well in both spring and fall.

Gardeners often wait excitedly for garden planting season to arrive. Beginning gardeners sometimes experience confusion over when to plant their well-planned crops, however. Proper planting dates ensure optimal growth and crop production, but these times vary greatly, depending on location. For best results, pay close attention to specific factors such as temperature and moisture level in the soil.

Cool-Season Vegetables

Leafy vegetables, including lettuce, Swiss chard and mustard greens, grow best in cool weather. This makes them a spring or fall crop, depending on location. Some, like the Swiss chard, continue growing throughout the summer months. Most stop growing as the weather warms. An example of this is lettuce, which bolts and goes to seed once temperatures rise. Other cool-season vegetables include beets, carrots and onions. Gardeners in far northern areas of the U.S. have to wait until April or May. In southern areas, gardeners often plant these vegetables in late winter. Gardeners in more moderate regions in the U.S. should plan on planting cool-season crops in mid-March or early April.

Warm-Season Vegetables

Some vegetables thrive only in hot weather. Examples include tomatoes and green peppers. These plants sustain long-term damage if temperatures fall below roughly 50 degrees Fahrenheit. Gardeners must wait until after the last average frost date in their location before planting these vegetables. In areas with a shorter growing season, transplants allow gardeners to grow these vegetables without the risk of losing the crop to an early frost at the end of the growing season. Most gardeners in the northern half of the U.S. must wait until around mid-May to plant these vegetables. In the south, gardeners should take special care to keep vegetables well watered during periods of extreme heat and drought. Although these vegetables enjoy hot temperatures, they often deteriorate when temperatures reach 90 degrees Fahrenheit or higher.

Multiple Plantings

Making multiple plantings in a garden increases production. Consider creating a fall garden with cool-season vegetables. Fall gardens must be planned so harvest occurs before the first average frost date in your area. This means sowing seeds in mid to late summer in many areas, with southern gardeners waiting slightly longer to allow cooler temperatures to arrive. Follow guidelines from your local county extension office for best results.

Considerations

The optimal planting time for vegetable seeds varies from year to year, even within a given location. Waiting until ground thaws and wet soil dries provides the best way to gauge planting readiness. Likewise, base fall planting on current temperatures and weather conditions. Preparing soil starting in the fall provides ample time to remove debris, analyze soil samples, add organic material and other soil amendments, and till the ground. Beginning seeds indoors extends the growing season, providing a head start on vegetable production.

References

• Iowa State University Extension; Planting a Home Vegetable Garden; Henry G. Taber
• University of Florida Extension; Florida Vegetable Gardening Guide; J.M. Stephens
• Colorado State University Extension: Growing Cool-Season Vegetables
• University of Tennessee Extension; Guide to Spring-Planted, Cool-Season Vegetables; David W. Sams
• University of Tennessee Extension; Guide to Warm-Season Garden Vegetables; David W. Sams

Resources

• Oregon State University Extension: Growing Your Own Vegetables