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5 Tips to Keep a Greenhouse from Freezing

Keep your Greenhouse from Freezing
January 26, 2024
Amanda Curry
Read Time
2 minutes

With colder temperatures just around the corner, it’s time to start prepping your home for the winter months ahead. For some of us, that means taking preventative measures to keep our winter greenhouse in tip-top shape in order to prevent freezing.

Greenhouses are a wonderful way to extend the growing season. Depending on where you live, you may need to think about how to heat your greenhouse. Cooler temperatures mean slower growth, which isn’t good news for those that have a greenhouse. Keeping your greenhouse temperatures above freezing can be tricky, however, here at LeafFilter, we have our thumb on some of the best ways to generate heat in your greenhouse.

1. Install a Heater

Installing a heater in your greenhouse is the most obvious solution for keeping your greenhouse from freezing. You can try using a space heater or even install something a bit more permanent. If you are going to install a heater in your greenhouse, remember to always keep heaters away from flammable materials and make sure they are properly installed.

If you need some assistance with your heater installation, it may be worth it to contact a local HVAC professional.

Prevent your Greenhouse from Freezing

2. Use Black Painted Barrells to Maintain Heat

If you are looking for a more natural way to keep the heat inside of your greenhouse, try painting the outside of several 55-gallon plastic containers with flat black enamel then fill them three-quarters of the way with water. Next, place your plastic container wherever it will receive the most sunlight. The black plastic containers will retain lots of heat. At night when the temperatures drop, the heat from the water will warm your greenhouse.

If done correctly, the greenhouse can stay an average of 20-30 degrees warmer than the outside temperature!

3. Push Warm Air Down

Since hot air rises, you can try keeping warm air contained and lower with a plastic or aluminum cover. Simply place your plastic cover across the top of the greenhouse to separate the peaked portion of the roof from the rest of the greenhouse. Blocking this “dead space” off in the winter will keep your greenhouse warmer.

4. Reuse Compost

You may not realize it, but the natural breakdown of organic material to make compost generates a lot of heat. That’s because the bacteria that is breaking down the material will generate heat. One way to use compost in your greenhouse is to top your garden beds with fresh compost before the cold weather hits. This will keep your plants warm. Remember, the thicker the layer, the harder the bacteria will work to keep your plants warm. We recommend spreading on a layer that is 2 to 3 inches thick.

5. Insulate your Greenhouse

Often overlooked, it’s important to insulate your greenhouse, just like it is your greenhouse. To retain as much heat as possible, seal off any small cracks or gaps by applying a silicone caulk.