How Much Warmer Is A Greenhouse Than Outside: Keep Growing All Year

When you live somewhere cold or winter months hit, a greenhouse stays warmer than outside, but by how much? Can your plants survive freezing weather inside? There are ways to ensure your greenhouse stays warm all year round. For example, you can insulate or add an electric greenhouse heater to maintain year-round growing conditions. There’s no reason an outside greenhouse needs to be a part-time structure. However, make sure to install vents for summer months and airflow if you live somewhere hot. All plants have a preferred soil type, but did you know they also have preferences regarding moisture and heat? Keeping your greenhouse temperature regulated takes a little effort, but it’s well worth the time. You can grow fresh produce in any climate and season with the right information. I’ll walk you through everything you need to know about greenhouse warming so you can grow year-round.


How much warmer is a greenhouse than outside? A greenhouse can be up to thirty degrees warmer inside than the outside air. Proper insulation is vital to maintain your greenhouse’s inside temperature, especially in freezing weather. However, a well-built greenhouse can keep plants above freezing even when outdoor temps drop to negative seventeen. Adding a heater can also help. 


What Is The Maximum Temperature For A Greenhouse

Although your greenhouse is warmer than outside, that is not always a good thing. You need to keep your plants above freezing in the winter months, or most of them will die. Alternately, in summer, you can easily overheat and kill plants.

Most plants are happy around eighty to eighty-five Fahrenheit. There are notable exceptions, and some are more malleable than others. That said, it would be best if you never let your greenhouse get over ninety degrees.

Using vents and good airflow in the hot months is crucial. It would be best if you had both cooling and heating for a healthy all-season greenhouse.

When your plants need a warmer indoor climate, I recommend the Bio Green PAL Electric Fan Heater for Greenhouses. This small fan heater can keep up to a hundred and twenty square feet of greenhouse toasty all winter. With IPX4 splash-proofing, you don’t need to worry about the moisture levels inside. Have Amazon ship to your door fast by clicking here. 


How To Keep A Greenhouse From Freezing

If you know any casual gardeners, then you’ve probably seen them rush outside to drape sheets over plants, so they don’t freeze. Even though your greenhouse is warmer than outside, there are times when it will still get cold enough to freeze. Luckily, you can take inspiration from these small houseplant keepers and apply it to your larger greenhouse.

Sheets and fabric are less effective than a reflective cover. Instead, hang up foil or mylar blankets over your greenhouse when it gets unexpectedly cold. Naturally, you may still need a heat source, but this will help reflect the heat back and keep it inside.

Additionally, you can use a couple of layers of frost-proof fleece if you live somewhere especially cold. This is also useful to keep around for those times when the power goes out. Otherwise, an electric heater and a reflective roof and window cover are superb.

Make sure you get enough foil or mylar to cover the whole greenhouse. I suggest mylar sheets because they are cost-effective and easy to glue together for a large cover. Moreover, they fold up very small for storage.

Keep in mind; you will need rocks or some other way to anchor your cover in place. Otherwise, it will blow away as mylar is very lightweight.

Stop stressing about low temps with a Dr. Heater Greenhouse Infrared Heater from Amazon. Not only is this lightweight, low-maintenance heater easy to use with just one setting, but it can also handle up to a hundred fifty square feet. Best of all, Dr. Heater is also splash-proof so that you can water without worries. Read the excellent reviews when you click here. 


How Do You Keep The Temperature Constant In A Greenhouse

Some temperature fluctuation is normal despite the way a greenhouse stays warmer than outside. If you are growing particularly finicky plants, you may want to keep it more precise. Using heat and airflow to regulate is how you change the temperature. However, it is necessary to check the temps if you want to regulate them.

A thermometer is an obvious solution. You can mount a traditional or digital thermometer on an outside window and another in the center of your greenhouse for precision temperature readings. If you cannot be in the greenhouse all day, but you still want to keep an eye on it, a security camera or video baby monitor will help you keep a constant temperature.

With all the smart technology available today, it is easy enough to network a switch or outlet for remote control via your smartphone. Otherwise, make sure you check the weather for the day and adjust manually when you go to water, and check on your plants in the mornings.

Maintain a constant temperature in your greenhouse with the iPower Electric Heater Fan from Amazon. This model heats up fast, but it also has overheat protection. Splashproof and versatile, you’ll love the Power Heater. The easy-carry handle makes it simple to move. Best of all, an adjustable heating range from -58°F to +210.2°F means you can choose the perfect temperature for your plants. Get yours by clicking right here. 


How Do You Keep A Greenhouse Warm In Winter Without Electricity

There are numerous ways to heat a greenhouse without electricity. A well-sealed greenhouse will always be warmer than outside in winter, at least by a small amount. However, there is a lot more you can do.

I recommend always having a backup electric heater in case of extreme temperatures. That said, you will use it less if you already have one of the following methods in place to maintain heat.


If you’re new to compost, then this idea probably seems ‘crazy,’ but compost creates heat as it breaks down. While it takes a bit of foreknowledge to create and maintain a proper compost pile, it will radiate warmth. On average, compost can get from a hundred forty to around one sixty, and deeper piles heat up more.

Coops & Animal Homes

Whether it’s chickens, rabbits, or something else, building your greenhouse with your animal homes attached is a great way to provide warmth. Rabbit droppings, in particular, make a superb source of warmth. Just as with compost, the droppings go through a heating process as they decompose. Plus, it’s great for your soil to have both animals and a garden.

Dig Deeper

When you dig down into the earth and put the floor of your greenhouse below the surrounding earth’s level, you get better heat regulation. Not only is the ground a great insulator, but you can take advantage of natural wind protection. Plus, dirt absorbs heat during the day, and some of that will radiate back into your partially underground greenhouse.

Double Windows

If you live in a cold climate, you already know that double-paned windows will prevent internal temperature changes. Two panes of glass are great. However, ideally, you want a double pane with a layer of argon insulating gas between.

Insulate Better

This may seem overly obvious, but you need better insulation. Checking bi-annually for any cracks that need sealing is a good start. You can build up outer walls and heat/soil retaining walls in your beds.

Raise Beds

Move your plants off the ground and into raised garden beds. Not only do stone and cement walls hold heat, but so will all the dirt inside. Moreover, since thermodynamics laws state that heat rises and cold sinks, the higher your plants, the warmer they will be.

Thermal Mass

Rock walls and compost are not the only way to bring more thermal mass to your greenhouse. Store water in large, black-painted barrels. Over the course of the day, these barrels will absorb heat, and so will the water inside. Later, as the sun sets, that energy will disburse as heat within your greenhouse.

Use The Sun Two Ways

There are two fantastic no-energy ways to use the sun. First, reflect it into your enclosed greenhouse with white paint facing the winter sun. Second, build or buy solar heaters that will help increase the daytime temperatures.

For backup heat in your greenhouse, I suggest the AgiiMan Greenhouse and Garage Heater from Amazon. An extra-long cord reaches where you need it. With no exposed coils and an automatic shutoff, you won’t overheat your space. Learn more when you click here. 


Final Thoughts

Don’t worry about freezing plants. Instead, grab a good greenhouse heater for those chilly evenings and winter days. Your enclosed planting area will stay toasty, and you will always eat well. Year-round growing isn’t as difficult as it first seems. You need the right heater and some good information to make it work.

It’s important to make sure plants don’t freeze. When the water inside them dips below thirty-two, it forms ice crystals. As you might have guessed, growing crystals inside a body can be pretty damaging. Your plants probably won’t survive the experience.

By insulating well and adding a little heat when you need it most, your greenhouse plants will stay happy. It may be winter outside, but inside your greenhouse, it can be spring all year.

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