How to Heat Bricks for Small Greenhouses
Once it had been common for people to heat a brick, wrap it into a cloth and take it to bed. While central heating and electric blankets replaced the hot brick on your bed, your plants appreciate the heat radiating out of a warm brick in the ocean. Bricks are used as thermal mass, generally as a strong wall on the northern side of the greenhouse. In a small greenhouse, though, a huge brick wall might actually overheat the plants. Rather, heat a few bricks in the oven and set them near your plants for mild heat on a cold winter night.
Use Your Oven
Preheat the oven to 300 degrees Fahrenheit.
Put a couple of bricks to a large cookie sheet in the oven. Leave a 1-inch space between the bricks.
Heat the bricks for 20 to half an hour. Carefully remove the bricks in the oven, one at a time, using oven mitts to protect your hands. Allow the cookie sheet to cool before washing and putting it off.
Place the bricks in the greenhouse, close but not touching the plants. Stacking the bricks together helps them retain heat longer on a cold winter night.
Let the Sun Do It
Wrap every brick in plastic.
Place the bricks in a row within the greenhouse, where they receive the sun’s rays for at least 6 to 8 hours.
Move the bricks close to the tenderest plants in the greenhouse when it begins to get dark. The bricks will emit a gentle warmth through the evening.