Start Every Seedling You Need in a Spare Corner With This

Peppers want 80-degree soil and a March windowsill is 55. A heat mat under the tray closes that gap for pennies of electricity, and the thermostat probe is the part that matters - an unregulated mat cooks seedlings on a warm afternoon. Germination that took three stubborn weeks happens in five days.

Take the mat away once they are up - warm soil grows damping-off too.

The thin drugstore trays crack the first time you lift one loaded with wet mix, and a cracked tray dumps forty seedlings on the floor. Heavy trays are a buy-once item: rigid enough to carry one-handed, and the no-hole bottoms let you water from below, which is the single best trick for not washing seeds out of their cells.

Bottom-water: pour into the tray, let the cells drink for twenty minutes, tip the rest.

Leggy, pale, flopping seedlings are light-starved - a south window in March delivers a fraction of what they want. A strip light two inches above the canopy grows squat, dark green plants that shrug off transplanting. These link together end to end, so one outlet runs a whole shelf.

Keep it close - two to three inches above the leaves, raised as they grow.

Soil from the garden brings weed seeds, fungus gnats and damping-off spores indoors with it, and heavy soil suffocates fine roots in a cell. Sterile seed mix is loose, clean and holds water without waterlogging. One bag starts hundreds of cells.

Wet the mix before it goes in the trays - dry peat repels water the first time.

Nobody believes they will forget which cell is which, and everybody does - two unlabelled pepper varieties are indistinguishable for three months, which is exactly as long as it matters. Pencil on plastic outlives every marker: sun fades Sharpie to nothing by June.

Pencil, not marker. Graphite does not fade.