How Can I Heat My Greenhouse for Free in the Winter?

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How Can I Heat My Greenhouse for Free in the Winter?

Heating a greenhouse in the winter can get pretty expensive.

However, without that heating, your plants are more likely to die, unless you live in a place that has warmer winters. It’s a prime example of being caught between a rock and a hard place: either find a way to afford the costs of heating, or don’t have a winter greenhouse at all.

But keeping a greenhouse warm without the exorbitant price tag is possible. Fortunately, there are a few free and low-cost tricks you can use to bring the heat to your cold weather garden.

If that seems impossible, we’ll show you that it really isn’t. In this guide, we’ll be discussing how you can heat your greenhouse for free in the winter.

Situate You Greenhouse Properly

Put it somewhere it will get the most light.

"The sun is your greatest free source of heat, so make sure you’re using it to your advantage."

One of the easiest ways to ensure your greenhouse is warm during the winter will be placing it properly. In the northern hemisphere, this means putting it where as many of its panels as possible will face the south.

If you’re in the southern hemisphere, you’re most likely in a place where the greenhouse will stay sufficiently warm year-round without much help. However, if you’re curious about where to get the most sunlight, anyway, you would want your greenhouse facing the north.

The sun is your greatest free source of heat, so make sure you’re using it to your advantage.

Pay attention to the panels.

In the event you’re still in the process of looking for a good winter greenhouse, then you can take the steps to ensure you’re getting one that will be easier to heat in advance. Focus on its panel situation, if it’s the kind of greenhouse with panels instead of being made entirely from plastic.

Look at how the panels are positioned. Roof panels that are slanted work amazingly well, because they’re able to catch the sunlight longer. Their angle allows them to let sunlight in even during those long winter days where the sun isn’t high in the sky for long.

Read Also: 6 Best Greenhouses for Winter Growing

Install a thermostat or thermometer to watch the temperature.

Understanding what your plants need will be the most important part. Research what their temperature requirements are first, so you’ll know what’s too hot or too cold.

Then, once you know what kind of heat they need, make sure you add a thermostat to your greenhouse. After all, you’ll need to be able to make sure you’re hitting the right temperature range. You can’t accurately do this without a thermometer or thermostat.

With a thermometer or thermostat installed, be sure to check it often during the winter. If it’s outside of the ideal temperature range, you’ll be notified right away that you need to make adjustments.

Read Also: What Can I Grow in a Greenhouse in the Winter?

Ways to Heat your Greenhouse for Free in the Winter

Now onto the good part: how to actually heat your greenhouse for free or very low-cost.

We’re going to make a distinction here. Not all of the methods in our list are ways of heating the greenhouse itself – some are just tricks you can use to keep your plants warm.

Other tactics in this guide will have a very slight cost involved.

Without further ado, here are a few strategies you can use to keep your plants warm:

Keep your plants off the ground.

"You wouldn’t want your plants sitting on what’s essentially a big block of ice."

Elevating your plants off the ground is a free and easy trick you can use to keep them warm. Think about it: the ground gets really cold during the winter as the earth freezes.

You wouldn’t want your plants sitting on what’s essentially a big block of ice. That will just expose them to freezing temperatures that would cause them harm.

The solution is making sure they don’t come into contact with the cold. Some greenhouses have shelves built into them that you can use to raise your plants off the ground.

If your greenhouse doesn’t come with shelves or hangers, you can consider adding shelves of your own. Otherwise, you can use stands for any potted plants you might have.

And when stands or shelves aren’t an option, you can always line the bottom of your pots with pebbles. These pebbles will function as a makeshift barrier between your plant’s delicate roots and the cold earth.

Insulate the walls with bubble wrap.

Okay, we’re cheating with this one a little bit. Technically, this isn’t free, but it won’t cost you very much, so we’re at least not cheating a lot.

Try lining the walls of your greenhouse with bubble wrap. Use bubble wrap with bubbles that are as large as possible, because bigger bubbles will provide better insulation.

This trick might sound a little silly, but it really does help. It covers any small gaps or cracks that might be in the walls, so no cold air can blow in and heat won’t escape as easily.

Plus, when it starts to warm up again, you can remove the bubble wrap and pop some of the bubbles for fun.

Seal any openings with tape.

"Windows and doors are easy points of entry for cold air."

Don’t have any bubble wrap? No problem – you can use tape instead.

Lining every inch of the walls with tape is impractical, though, and would take far too much time. We’re proposing a much more modest solution here: cover the areas around doors and panels with it instead.

Windows and doors are easy points of entry for cold air. By covering the places around them with tape, you’re sealing off openings for cold to come in, and for heat to escape from.

While you’re doing that, check for any cracks in the walls. If you find any, make sure to cover those with tape, too.

Store 55-gallon water barrels in your greenhouse.

This one sounds really weird, but the science backs it up.

Water can absorb heat from the sun during daylight hours. When the temperature drops, it will start releasing the energy that it stored as more heat. It’s sort of like solar lights that gather energy during the day and then turn on at night.

To take advantage of this quality, make sure you keep the water barrels somewhere in the greenhouse where they will get as much sunlight as possible during the day. For the best results, use several of them at once rather than just one or two.

Compost bales of hay in your greenhouse.

Another trick some gardeners use in their greenhouses is composting.

When something composts, it naturally gives off energy in the form of heat. By composting something as large as a hay bale, you’ll get a decent amount of warmth.

As a bonus, you can grow things in the compost. It’s like a two-for-one deal. 

Of course, this method isn’t possible for everyone, because it will take up a lot of space. However, if your greenhouse has the room for it, think about composting a hay bale or two.

Wrap Up

There you have it: cheap or completely free ways you can help warm your greenhouse during the winter.

The methods in this guide will aid in temperature management, but you may still want to consider getting a heater like this one for your greenhouse. A heater is one of the more efficient ways of making sure a space is kept up to temperature, and many are quite affordable.

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