Quick Answer
For most vegetable seeds, it's ideal to start indoors 4-6 weeks before the last frost date in your area, when soil temperatures are still too cool for direct sowing. This allows seedlings to develop a strong root system and harden off before transplanting outdoors.
Choosing the Right Seeds
When selecting seeds for indoor starting, choose varieties that mature quickly, typically within 50-60 days, and are resistant to common pests and diseases. Consider growing cool-season crops like lettuce, spinach, and broccoli, which can tolerate cooler temperatures and can be directly sown in the garden as soon as the soil can be worked. For warm-season crops like tomatoes and peppers, start seeds 6-8 weeks before the last frost date to ensure adequate time for transplanting.
Starting Seeds Indoors
Sow seeds in seed starting mix, 1/4 inch deep and 1-2 inches apart, in small containers or cell packs. Provide adequate light, usually 12-16 hours of supplemental lighting per day, and maintain a consistent temperature between 65-75°F (18-24°C). Water gently but thoroughly, and fertilize with a balanced, water-soluble fertilizer once seedlings have two sets of leaves. Transplant seedlings outdoors when they have 2-3 sets of leaves and the danger of frost has passed, hardening off the seedlings over the course of 7-10 days.
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