How to start seeds indoors without a greenhouse

The three things that matter

Warmth at the root (75–80°F for tomatoes and peppers — a heat mat, not a radiator). Light from above, two inches from the leaves, 14–16 hours (a shop LED, not a windowsill). A sterile, fine mix in a tray that drains.

Grocery-store peat pellets work once and then collapse. A 1020 tray with a 5×5 insert from a farm supplier lasts a decade. That is the first upgrade that pays for itself.

The sequence

Sow. Cover lightly. Dome on until germination. Dome off. Light on. Bottom-water. When they have two true leaves, pot up or thin. One week before they go outside, harden off: an hour in shade the first day, longer each day, in by night until nights are safe.

Leggy seedlings are a light problem, not a fertilizer problem. Move the lamp down.

What not to start indoors

Root crops (carrots, radish, beets) and beans and peas. They hate transplanting. Direct-sow them. Squash and cucumber can be started in pots two to three weeks before last frost if your season is short — any longer and they stall.