Are you building a new greenhouse? If so, you are probably overwhelmed with ideas and questions about how to make your greenhouse the most effective it can be. One of the biggest questions that new gardeners have when first building a greenhouse is how they will manage to adequately and safely provide heat. Electric heaters can be expensive and dangerous, if left unattended, and gas heat is not good for the plants.
Fortunately, there is a multitude of greenhouse heating options that require little or no cost at all. The best part? They’re completely safe. Below, we will outline the top five ways to safely, effectively, and cheaply heat your new greenhouse project.
Are you ready? It’s easy. You can avoid the need to heat your greenhouse entirely by simply making sure that your plants are retaining their heat from the day throughout the night. This can be done in a variety of ways, but the simplest is to use horticultural fleece. By laying a large, fleece cloth over your plants at night, you will be helping them hold in the heat they have absorbed throughout the day.
As an added bonus, you will also be keeping any frost from settling on your leaves and stems, which can kill your plants instantly.
There is a downside to the use of the fleece, however. You must remember to remove it first thing in the morning, or it will have the opposite effect. Your plants will be unable to absorb heat and will, instead, hang onto the cold from the previous night. Also, horticultural fleece does not allow light in, which can severely impact the photosynthesis process of plant growth.
If you have the time to spare, though, using fleece is a tried and true method of greenhouse growers the world over. It is a low- cost answer to the problem of late- night frost and a quick, easy task to undertake.
You can also try horticultural bubble wrap. Yes, I said bubble wrap. The same stuff you used to love to pull out of packages and play with as a kid (and probably still do) can be used to provide light and heat for your plants. The large bubbles in the plastic attract and diffuse more light, spreading it, along with the heat it produces, throughout the greenhouse.
Greenhouses that use horticulturalist bubble wrap in place of solid sheets of plastic report up to 10 degrees difference in internal temperatures! If you can avoid the urge to pop the bubbles, the plastic bubble sheeting is a low cost and inventive way to keep your plants happy and healthy. It also comes with the added bonus of a more even and “whimsical” appearance to the light within your greenhouse, which can create a cheerier atmosphere for your gardening work and a more inviting appearance for any customers you may have in a commercial greenhouse setting. The bubble wrap can be purchased at most gardening stores or online for as little as $1.50 a square foot.
Let water do the work. A lot of greenhouse keepers use plastic bottles or drums filled with water to capture and hold heat. Have you ever visited a greenhouse and seen rows of large, black plastic drums filled with water lining the walls? Some might assume the water is there to provide humidity for the plants. While that is an added bonus of this heat-retention trick, the real reason gardeners often employ these drums is for their ability to hang onto heat.
The dark drums attract the light from the sun throughout the day, warming the water. As temperatures fall at night, the water begins to cool, releasing its warmth into the air. A small amount of bleach (approximately 1 teaspoon per gallon) added to the drums will prevent any algae or other “gunk” from growing inside of them, but will not release a high volume of chemicals into the air that would be bad for the plants.
While it is not advised to water your plants directly from the barrels with bleach added, the humidity the barrels emit will not be toxic to your crops. If possible, line the barrels along the north wall of your greenhouse- this is where they will catch the most light throughout the day!
Take a hint from Ancient China. Years ago, Chinese gardeners built their own, special kind of greenhouse. These greenhouses had three walls, made with brick, clay, or other earth- sourced materials. These walls faced the west, east, and north sides of the building. On the south side of the greenhouse, the gardeners used a transparent shroud or glass to allow the light to enter the building. Throughout the day, as the inside of the building heated, the heat would also be absorbed into the three earth- sourced walls of the building.
At night, the gardener would cover the transparent side of their greenhouse with a heavy curtain or drape, to help hold the heat in. As temperatures fell, the heat would creep out of the heavier walls, heating the inside of the building throughout the night.
A well- built “Chinese greenhouse” can hold temperatures up to forty- five degrees higher than the outdoor temperature at night. The best part is the heavier walls also provide stability to the building, making it a cost- effective and smart method of gardening even today!
Double your fun with a composting station. Using manure, you can create a composting corner to your greenhouse. The benefits of this endeavor are immeasurable. You create great substrate for planting, you reduce your waste, and you develop yourself a new heat source!
You can compost a lot of different things- kitchen scraps, old newspapers, lawn clippings, or even the leaves you sweep up off the greenhouse floor! As the manure decomposes the compost, heat will naturally release. You won’t want to use this compost alone to plant, though. Mix in soil to create a more friendly environment for rooting. Some composting greenhousers are bold enough to include the source of their manure within the greenhouse walls, also.
Keeping rabbits or chickens inside your greenhouse puts everything in one tight-knit area, creating an easy and effective work station. You’ll just need to make sure you watch where you step, keep an eye on the temperatures throughout the day to ensure the well-being of the animals, and be sure the animals can’t get to your crops. Their body heat, also, can provide a great source of heat throughout the night once the sun goes down. All in all, it’s a win-win situation for everyone!
Whatever method you choose, keep in mind that nothing comes without trial and error. What seems to look like a good idea on paper, might not be the best fit for you. Give it some thought, and try out more than one! Also, don’t be afraid to try multiple sources of heat in conjunction with one another.
By implementing the methods that best fit you and your individual gardening style, you may even come up with something new and unexpected! Best of luck with your gardening and don’t forget the most important part of a greenhouse project- Have fun!