When to Start Seeds Indoors for Spring 2027

By Priya Sharma · October 8, 2026

The Seedling Calendar That Actually Works

Most gardeners start seeds too early or too late. The sweet spot depends on your last frost date and the crop's growth rate. Here is a week-by-week guide for spring 2027.

12 Weeks Before Last Frost

Onions, leeks, celery, and parsley need the longest head start. Sow them in late January to early February in most temperate zones. Use a seed-starting mix with no fertilizer — seedlings need sterile conditions until true leaves emerge.

8 to 10 Weeks Before Last Frost

Peppers, eggplants, and herbs like basil and oregano fall in this window. They need warmth — keep soil temperature at 75-80°F for germination. A heat mat under seed trays cuts germination time in half.

6 to 8 Weeks Before Last Frost

Tomatoes, broccoli, cabbage, and cauliflower. These are the most common indoor starts. Transplant them into 4-inch pots once they have two sets of true leaves. Begin hardening off two weeks before your planned outdoor transplant date.

4 Weeks Before Last Frost

Cucumbers, squash, melons, and zucchini. These hate root disturbance, so sow them directly in biodegradable pots. They germinate fast — expect sprouts in 5-7 days at 70°F.

Direct Sow After Last Frost

Beans, peas, carrots, radishes, corn, and sunflowers do better direct-seeded. Their roots do not tolerate transplanting. Wait until soil temperature reaches 60°F for beans and corn, 45°F for peas and carrots.

Hardening Off Protocol

Move seedlings outdoors for increasing periods over 7-10 days. Day 1: one hour in shade. Day 3: three hours with morning sun. Day 7: full day outdoors. This gradual exposure prevents transplant shock and sunburn.