Greenhouse heating helps your plants grow better

Although it’s possible to grow all year round in an unheated greenhouse, adding greenhouse heating makes a huge difference in the winter months. Plants grow much better with in a greenhouse with heating, and you can start growing much earlier in the season than you would be able to in an unheated greenhouse.

Harvst 3-Season and 4-Season mini greenhouses are fitted with safe, low voltage heater cables to keep air and soil warm.

Even if outside temperatures are freezing, the inside of your greenhouse will be warm enough for plants to keep growing.

Heater cable in greenhouse
12v heater cable

Harvst heater cable, as fitted to our greenhouses

Harvst 12v heating cable / soil warming cable is great for warming up the interior, running under growing containers, or for laying in the soil under the greenhouse.

Supplied as a 4m length, it’s strong, waterproof and reliable.

The heater cable is self-regulating, which means it stays at a constant temperature regardless of the ambient temperature. On a colder day, it will use more power to stay warm, and on a warmer day, it will use less. The target temperature is approximately 50 degrees. Ensure it doesn’t come into contact with roots or plants. We recommend running the cable along the shelves under your growing trays to warm the soil.

How warm can the Sprout mini greenhouse get?

For a typical UK winter, you can expect soil temperatures in your growing containers to stay above 10 degrees C, especially if you’re combining your space heating with grow lights, which also give off a lot of warmth. Run the heater cable through the mesh shelves and place growing containers (eg seed trays) on top.

Can I run heaters with a Solar Sprout greenhouse?

No, the laws of physics dictate this one. There’s just not enough energy from a reasonably sized solar panel and battery to provide the power that a heater needs.

Can I use a Harvst mini greenhouse in the north of Scotland?

Yes, absolutely, though if the outside temperatures are significantly lower than zero degrees your plant growth will slow down. Most plants like soil to be above 5-10 degrees to grow well…. though it does depend a huge amount on what plants you are growing. Choose plants that don’t mind the cold as much.

How many heaters can I power?

The Harvst control unit and mains power supply has a maximum capacity of 150 Watts.

Each heated cable is approximately 60W at max (this changes significantly based on how hard it’s self regulating). If you’re just running heater cables, then two is the maximum.

The control unit is smart enough to make the most of power, and also factors that you might be running hot grow lights too. If lights are off, both heater outputs can be run. If lights are on, then only the top heater output will be run.

Can I control mains powered heaters?

Not at the moment. In the future we may release a remote switch, controlled by the Harvst system. The inside of a Sprout mini greenhouse is a wet environment and non waterproof mains heaters should never be used.

When should I use heated seed trays?

If you have a 3-season heated greenhouse then you will have spare output capacity (as you’re not using grow lights), so you could add heated seed trays for germinating plants faster.