How to Start Seeds Indoors Under Grow Lights

Set up full-spectrum LED grow lights 6-12 inches above seed trays, maintain 65-75°F soil temperature, and provide 14-16 hours of light daily for optimal germination and seedling growth.

1. Pick Full-Spectrum Lights First. Select full-spectrum LED grow lights that produce both blue and red wavelengths. Position adjustable light fixtures on a shelf system or hanging setup that lets you raise the lights as seedlings grow. Calculate 20-40 watts per square foot of growing space. Avoid incandescent bulbs which generate too much heat and lack proper spectrum.
2. Create Your Growing Station. Set up a dedicated space away from windows to control light exposure completely. Use waterproof trays to protect surfaces and ensure good air circulation. Install a timer for your lights to maintain consistent photoperiods. Keep the area at room temperature between 65-75°F for most seeds.
3. Fill with Sterile Mix. Use sterile seed starting mix rather than garden soil to prevent disease. Fill cell trays, peat pots, or small containers leaving quarter-inch headspace. Moisten the mix until it feels like a wrung-out sponge but not soggy. The mixture should hold together when squeezed but crumble when disturbed.
4. Sow at the Right Depth. Plant seeds at a depth roughly twice their diameter. Tiny seeds like lettuce go barely under the surface while larger seeds like beans need half-inch depth. Place 1-2 seeds per cell for most vegetables. Cover lightly with seed starting mix and gently firm the surface without compacting.
5. Position Lights Precisely. Start with LED grow lights 6-12 inches above the soil surface. Closer positioning provides more intensity but watch for heat stress. Fluorescent lights should be 2-4 inches away. Adjust height as seedlings emerge to maintain proper distance from the top leaves.
6. Set Your Light Schedule. Program lights to run 14-16 hours daily for most vegetables and flowers. Some plants like tomatoes and peppers prefer 16-18 hours while cool-season crops need 12-14 hours. Provide 6-8 hours of darkness daily as plants need rest periods for proper development.
7. Check and Water Daily. Check soil moisture daily by touching the surface. Water from below using trays when the top feels dry but before it pulls away from container edges. Remove humidity domes once seeds germinate. Watch for stretching seedlings which indicates insufficient light intensity or wrong distance.
8. Nurture Growing Seedlings. Raise lights to maintain proper distance as plants grow taller. Begin diluted liquid fertilizer once true leaves appear, typically 1-2 weeks after germination. Start hardening off process 7-10 days before transplanting by gradually reducing light hours and exposing plants to outdoor conditions.