Why Start Indoors?
Starting seeds indoors gives warm-season crops like tomatoes, peppers, and eggplant a head start before outdoor temperatures are warm enough. It extends your growing season by 6-10 weeks, lets you grow varieties not available at garden centers, and costs a fraction of buying transplants.
Find exactly when to start each crop.
Open Seed Starting Calendar →What You Need
- Seed starting mix (not garden soil; it is too heavy and can harbor disease)
- Containers with drainage holes (cell trays, peat pots, or recycled yogurt cups)
- Light source (a sunny south-facing window or a basic LED shop light 2-4 inches above plants)
- Warmth (most seeds germinate best at 65-75 degrees; a heat mat helps in cold rooms)
- Labels (you will forget what you planted where)
The Process
1. Fill and moisten
Fill containers with seed starting mix and water until evenly moist but not soggy. It should feel like a wrung-out sponge.
2. Plant seeds
Follow the depth on the seed packet. A general rule: plant seeds twice as deep as they are wide. Tiny seeds like lettuce can be surface-sown and lightly pressed in.
3. Cover and warm
Cover trays with a humidity dome or plastic wrap until seeds germinate. Keep at 65-75 degrees. Most seeds do not need light to germinate, just warmth and moisture.
4. Provide light
Once seedlings emerge, remove the cover and provide 14-16 hours of light daily. If using a window, rotate trays daily. A cheap LED shop light 2-4 inches above the plants works better than any window.
5. Harden off
7-10 days before transplanting, gradually expose seedlings to outdoor conditions. Start with 1 hour in a sheltered, shaded spot and increase daily. This prevents transplant shock.
Calculate how many plants fit in your garden bed.
Open Plant Spacing Calculator →The most common mistake with seed starting is not enough light. Leggy, stretched-out seedlings are always a light problem. Move lights closer or add more hours.