Starting Seeds Indoors: Lights, Soil, Timing & Transplanting

Starting your own vegetable and flower seeds indoors saves money and opens up endless variety. Here's a streamlined guide based on years of trial and error.

When to Start

Most seeds need 6–8 weeks before your last frost date. Check seed packets for specifics. In the DC area (last frost ~early April), start peppers, tomatoes, and marigolds in late February to mid-March.

Light Requirements

Seedlings need 14–16 hours of strong light daily. A sunny window isn't enough—use fluorescent shop lights with one cool and one warm white bulb, kept 2–3 inches above the plants. Raise lights as they grow.

Soil & Containers

Use a sterile, soilless seed-starting mix (peat/vermiculite/perlite), not garden soil. It prevents damping-off, a fatal fungal disease. Sow in cell trays, cover with a humidity dome until germination, then remove it immediately for airflow.

Watering & Feeding

Keep mix evenly moist. Once true leaves appear, feed weekly with diluted fish/seaweed emulsion—low in nitrogen and salts. Avoid synthetic fertilizers at this stage.

Transplanting & Hardening Off

Pot up seedlings at least twice before moving outdoors. This prevents legginess and builds strong roots. Harden off over 7–10 days by gradually exposing them to outdoor conditions.

Special Notes

• Direct-sow lettuce, peas, spinach, and root crops—they don't transplant well.
• Cucumbers are prone to bacterial wilt spread by cucumber beetles. Use row covers early, and plant resistant varieties like 'County Fair'.
• Determinate tomatoes (like 'Early Girl') ripen sooner than indeterminate types (e.g., 'Beefmaster').

With consistent light, moisture, and patience, you'll grow vigorous starts ready for the garden.