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Seed Starting Indoors for Beginners: Lights, Timing and a $60 Setup

What to start, when, and the cheapest light setup that actually grows stocky seedlings.

Updated 2026-09-10

Which seeds to start indoors (and which not to)

Start indoors: tomatoes, peppers, eggplant, broccoli, cabbage, kale, lettuce, basil, onions. Direct sow instead: beans, peas, carrots, beets, radishes, corn, squash and cucumbers (they hate transplanting or grow fast enough outside).

When

Count back from your last spring frost: peppers and onions 8–10 weeks, tomatoes 6 weeks, brassicas 6 weeks, lettuce and basil 4 weeks. The planting calendar does the counting for you.

The $60 setup

A windowsill produces leggy, weak seedlings. What works: one shelf, two 2-ft LED strip lights 2–3 in above the seedlings for 14–16 hours a day on a $10 timer, and a heat mat under peppers and tomatoes until they germinate. Standard 1020 trays with cell inserts and a humidity dome. That is the whole list.

Step by step

1. Fill cells with moist seed-starting mix (not garden soil). Sow 2 seeds per cell, 1/4 in deep.
2. Dome on, heat mat on, until the first sprouts show. Then dome off, mat off, lights on.
3. Keep lights 2–3 in above the tops as they grow. Water from the bottom.
4. Thin to one seedling per cell with scissors. Feed at half strength once true leaves appear.
5. Pot up tomatoes into 3–4 in pots when they have two sets of true leaves.
6. Harden off: 7 days of increasing outdoor time, shade first, then sun, then overnight.

Common failures

Leggy stems (light too far away), damping off (too wet, no airflow: run a small fan), sunburn after transplanting (skipped hardening off).

What I'd buy first

Save this guide on Pinterest for planning season.