planting

When to Start Seeds Indoors: Frost Date Calculator & Planting Schedule

When to Start Seeds Indoors: Frost Date Calculator & Planting Schedule Start most warm-season vegetable seeds indoors 6-8 weeks before your last frost date, and cool-season crops 4-6 weeks before last frost. The formula is simple: Last Frost Date minus Weeks to Start equals Sowing Date. A tomato in Zone 6b (last frost April 20) should go into trays between February 23 and March 9. Plant too early and seedlings get leggy; plant too late and you lose weeks of productive growing season. An eager gardener I advised in Zone 6b (average last frost: April 20) transplanted $180 worth of warm-season seedlings -- tomatoes, peppers, squash, and basil -- outdoors on April 5 to "get a head start." A late frost on April 12 dropped temperatures to 28F. Every single transplant died. She replanted with store-bought transplants after the confirmed last frost, but the selection at the garden center was...