Heating

These mini-splits also cool, so the same units appear in our air conditioning range. For seed trays, heat mats and thermostats warm the root zone without heating the whole room. Both sit under HVAC.

Types of Grow Room Heating

Olympus Cold-Climate Heat Pumps

MrCool Olympus ENERGY STAR systems come in 9,000, 12,000, 18,000 and 24,000 BTU. They keep heating down to -13°F outdoors, and the 12,000 BTU size covers about 500 sq ft. A licensed installer sets them up, so pick Olympus for permanent greenhouses in cold climates.

DIY and Ceiling Mini-Splits

The DIY 4th Gen E Star uses a pre-charged quick-connect line set, so no vacuum pump is needed. It heats down to 5°F, with sizes from 12,000 to 36,000 BTU for about 500 to 1,500 sq ft. The Samsung 48,000 BTU ceiling head keeps walls clear in large rooms.

Soil Heating and Thermostats

The Jump Start 48 ft soil heating cable warms about 12 sq ft of bench to 77–85°F with its built-in thermostat. The Green Air CT-HT-2 runs heating and cooling from independent sensors, each switching its own outlets.

How Growers Use Heating

In a lit room, the lights add heat, so cooling often sets the unit size. Check that the same unit still covers your coldest nights. Olympus models keep heating far below freezing, while the DIY line stops at 5°F, so very cold sites may need backup heat.

Frequently Asked Questions

Will a mini split work in a greenhouse?

Yes. A ductless heat pump heats and cools a closed greenhouse from one unit, with the indoor head on a wall or ceiling. Choose a cold-climate model if winters drop well below freezing. MrCool Olympus heats down to -13°F, and the DIY 4th Gen works down to 5°F.

How to heat a grow room?

For a sealed room, a greenhouse heat pump is the usual choice: it heats in winter, cools under the lights and runs from one thermostat. A 12,000 BTU Olympus covers about 500 sq ft. In a small tent, start with a heat mat or soil cable under the trays instead.

Do mini splits work in cold weather?

Yes, within their rated range. The MrCool Olympus line is rated to keep heating at -13°F outside. The DIY 4th Gen is rated to 5°F. Below its rating, plan on a backup heater for the coldest nights, and check the condenser stays clear of snow.

How to use soil heating cables?

Lay the cable in loops at about 4 feet per square foot, and never let it cross or touch itself. Cover it with wire mesh, then soil or sand. The Jump Start cable works best in an enclosed, insulated box, and its thermostat holds 77–85°F.