Best Indoor Greenhouse and Grow Tent Kits for Vegetables, Herbs and Seedlings

For spring starts you do not need a tent. A 4-tier shelf holds one standard 1020 tray per tier, which is 72 seedlings in a 72-cell insert. Hang two 2 ft T5 LED bars under the tier above each tray and keep them 3 to 6 inches over the seedlings.

A heat mat under each tray holds the soil warm so peppers and tomatoes come up in days. Roll the clear cover up while the lights are on: it holds humidity for germination, but shop-style LED bars are not made for a wet enclosure.

Four trays with 80 W of lights for 16 hours a day and four heat mats run about $12 a month at the US average rate.

A 2x2 ft tent that is 6 ft tall holds one tomato or pepper plant, or about 8 heads of lettuce. A 2x4 fits along a wall and holds two fruiting plants or about 16 greens.

Leafy greens need about 260 PPFD on a 16 hour day, so a 2x4 of lettuce uses only about 90 W of the light's 220. Dim it and the tent costs about $10 a month to run.

Tomatoes and peppers want a daily light integral of about 20 to 30. On a 16 hour day that is about 430 PPFD, or roughly 300 W of LED over a 4x4. The 4x4 is the common choice for four plants, and its 80 inch height leaves room for the light above full-grown tomatoes.

A 4x4 holds about 107 cubic feet of air. Replacing it once a minute, plus 25% for ducting and a carbon filter, takes about 134 CFM, which a 165 CFM 4 inch fan covers on a middle speed.

A 5x5 holds six fruiting plants in 5 gallon pots. It takes about 470 W of light on a 16 hour day and about 210 CFM of exhaust, more than a 4 inch fan moves, so it steps up to an 8 inch fan in one of the tent's 8 inch ports.

Expect about $48 a month to run at the US average rate. A shorter light day does not cut that much: to give the plants the same daily total in 12 hours, the light has to run brighter for each of them.

Complete kits put a tent, an LED and an exhaust fan in one box, so there is nothing to match. You give up choosing each part, and the bundled light is often smaller than a separate one for the same footprint, so check its watts against what our sizer says you need.