When to Start Your Seeds: Create a Custom Seed-Starting Schedule

A seed-starting schedule tailored to your climate and setup is the secret to having robust, garden-ready seedlings at the perfect time. Here's how to build your own.

Sort Your Seed Packets

Separate seeds into two piles: direct-sow (plant outdoors) and start indoors. Direct-sow includes most root crops (carrots, beets, radishes), beans, corn, peas, melons, cucumbers, squash, and many annual flowers (zinnias, sunflowers, nasturtiums). Set these aside.

For the "start indoors" pile, read each packet. Look for "start X weeks before last frost." Sort into piles by recommended weeks (5, 7, 9, etc.). If only germination time is given, add 6 weeks. No info? Default to 6 weeks before last frost—adjust next year based on results.

Create Your Calendar

1. Find your average last frost date (search by zip code online).
2. Count back in weekly increments from that date. (Many gardeners use Saturdays as planting days.)
3. Label each packet with its week number and rubber-band piles together.

Example: Last frost May 15 → Week 4 = April 15, Week 11 = late February.

Adjust for Your Conditions

Start earlier (add 1–2 weeks) if:

• Growing in a cool basement/bedroom (<70°F) – germination and growth are slower.
• Using a cold frame, greenhouse, row covers, or pop-up covers – you can transplant earlier.

Start later (subtract 1+ weeks) if:

• Growing in a warm greenhouse or room (>70°F) – heat accelerates growth, risking overgrown seedlings.

Sample Schedule (Zone 4, Cool Indoor Start)

• Week 11 (Feb 20–26): Heliotrope, candytuft, primula, leek, early greens, viola, snapdragon
• Week 10 (Feb 27–Mar 4): Delphinium, matricaria, onion, parsley, oregano, impatiens, rudbeckia, early broccoli
• Week 9 (Mar 5–11): Pepper, coleus, shallot, eggplant, cherry tomato
• Week 8 (Mar 12–18): Tomato, alyssum, cleome, salvia
• Week 7 (Mar 19–25): Ageratum, zinnia, lettuce, radicchio
• Week 6 (Mar 26–Apr 1): Bachelor's buttons, agastache, aster, basil, marigold, sweet pea, calendula
• Week 5 (Apr 2–8): Sanvitalia, cabbage, convolvulus, nicotiana, lavatera, nigella, phlox, phacelia
• Week 4 (Apr 9–15): Morning glory, nasturtium, melon, cucumber, squash

Keep notes each year on transplant readiness and adjust. Gardening's unpredictability is part of the fun!