St. Louis Planting Calendar: When to Start Impatiens and Annuals

Timing Annual Planting in St. Louis: Frost Dates and Seed Starting

Success with annuals in St. Louis hinges on understanding the last frost date (typically May 1) and working backward for seed starting, then forward for safe transplanting.

Seed Starting Schedule

• Most annuals: Start seeds 6–8 weeks before last frost (mid-March)
• Impatiens and begonias: Start 12 weeks prior (mid-February) due to slow growth
• Hardy annuals (snapdragons, pansies): Can be set out 4 weeks before last frost

Transplanting Outdoors

Wait until the weekend after the last frost date for tender annuals. This buffer protects against late cold snaps. The same rule applies to assembling hanging baskets—unless you have a sunroom or grow lights, early indoor starts become leggy without adequate light.

Key Takeaway

Match your planting timeline to each species' growth rate and cold tolerance. Patience in spring prevents disappointment and plant loss.