Updated at: 13-10-2022 - By: Sienna Lewis

Were you ever curious how warm a greenhouse gets in the winter? Even if the plants are housed in a greenhouse, freezing conditions are not ideal for them. You must prevent your greenhouse from becoming too hot or too cold if you want to keep your plants healthy.

Greenhouse temperatures are affected by a wide range of factors that include your local climate, glazing, the outside temperature and more. A greenhouse’s temperature is typically 30 degrees Fahrenheit greater than the surrounding environment. Weather and greenhouse glazing might have an impact as well as the temperature outside.

How Cold Is Too Cold for a Greenhouse?

A greenhouse’s temperature can only be described as “cold” if we know what we’re growing in it.

In a greenhouse, you can have a hothouse, a coolhouse, or a combination of both. What matters is how you put it to use throughout the course of the year.

Temperatures must be maintained at 55 degrees Fahrenheit or higher in a hothouse and 45 degrees Fahrenheit or lower in a coolhouse.

That being said, any temperature below 55 degrees Fahrenheit for a hothouse and 45 degrees Fahrenheit for a cold house can be considered “too cold for a greenhouse.”………………………………………………………..

If it becomes too chilly outside, you’ll need a technique to keep your greenhouse warm.

Your greenhouse vegetables’ ability to endure varying degrees of cold varies as well. Depending on the temperature at which they are grown, greenhouse crops can be categorized into three main groups:

  • Crops that can withstand temperatures as low as 39 degrees Fahrenheit are known as cold-tolerant crops.
  • Crops that thrive in temperatures between 40 and 45 degrees Fahrenheit are known as cold-temperate crops.
  • It is possible to grow cold-sensitive crops in climates where the ambient temperature is over 46°F (7.2°C).

Minimum temperature (or base temperature) refers to the lowest temperature at which a plant is unable to grow. Plants do not produce leaves or flowers when the temperature is below the critical one.

Your greenhouse crops’ ideal growing temperatures are dependent on their starting temperatures, therefore you must take this into account when determining how hot your greenhouse should be.

The ideal temperature for your greenhouse crops is just as important and valuable to know. At this temperature, plant growth is the fastest.

This temperature ranges from 70 to 90 degrees Fahrenheit depending on the crop. This temperature range is critical for healthy plant growth in your greenhouse.

Outside, the temperature must go below zero degrees Fahrenheit before you begin to feel the chill in the greenhouse air.

Does a Greenhouse Work in the Winter?

Yes, I would say so. However, you must plan for winter planting. Insulation, pest infestation, and the type of plants you wish to grow are a few things to think about.

How Warm Does a Greenhouse Get During Winter - Krostrade


Because plants require energy (heat) to develop, you’ll want to think about that when planning your heating system this winter. Insulating your greenhouse is a great way to conserve energy and heat.

Pest infestation

During the winter, pests are drawn to warmer climates for the same reasons that plants are. Get rid of dead leaves, plants, stones, empty pots, and other objects that can house bugs to prevent serious harm.

Types of plants

Consider the practicality of the plants you intend to cultivate in your greenhouse before making a decision. Cold-season vegetables and herbs, like garlic, onion, beans, spinach and shallots, should be planted if the temperature doesn’t rise over 20 degrees F.

How Do You Keep Your Greenhouse Warm During Winter?

In order to thrive and produce a flavorful yield, plants require heat. If you want to keep your greenhouse warm in the winter, try these ideas:

Add insulation

Bubble wrap is a cheap and easy technique to insulate a room. Additionally, a covering of bubble wrap on the wall can help maintain heat and block off the cold. Better insulation can be achieved with larger bubbles.

Cover your plants

During the cooler nights, it is beneficial to cover your plants in order to provide additional warmth. Row covers, tarps, and horticultural fleece can all be used to keep the soil moist. Make careful to remove the cover during the day if it isn’t winter season, or if it is excessively humid.

Frost fabric can be used as additional insulation in places with harsh winters, such as Montana and North Dakota. Frost fabric retains heat while allowing rain and irrigation to freely flow into your greenhouse. Consider using frost fabric if you have plants that thrive in humid conditions.

Install a heating system

Installing a heating system in your greenhouse is a surefire way to keep it warm in the winter. Heaters, on the other hand, can be pricey, and once you switch them off, the heat is gone. You can heat greenhouses with heaters designed for this purpose. Instead of using extension cables in your greenhouse, consider using gas heaters instead. Make sure to spread the warm air throughout your greenhouse.

Insulate with bubble wrap

Protect your greenhouse from UV rays by using horticulture bubble wrap rather than package bubble wrap. The larger the bubbles, the greater the insulation and the more light it will let in. You can secure your bubble wrap with pegs, staples, or tape, but cleaning your windows first can help you save on light loss.

Bubble insulation can also be used to wrap outdoor pots, keeping rootballs safe from the cold and preventing cracks in your prized possessions.

Invest in a greenhouse heating system

If you’re looking for the safest way to keep your home warm, electric heating is your best option. By distributing heat more uniformly, fan heaters help keep your greenhouse from creating cold areas.

Propane and paraffin heaters work well in greenhouses without access to mains power, but you must be extra careful to keep windows and doors open on bright days to prevent mould from attacking your wintering plants.

Use the thermostat

Only heat your greenhouse when it is absolutely necessary to save money and resources. There are many thermostat-controlled electric greenhouse heaters on the market today, so you can program your heater to only turn on when the temperature dips below a predetermined degree.

Warm Up a Greenhouse for Winter

Use a thermometer

Make sure you have a thermometer with maximum and lowest readings if you aren’t using a thermostatically-controlled heater. To maintain a consistent temperature and maximize fuel efficiency, check the temperature every day and adjust your heater as necessary.

Choose the right temperature

Maintaining temperatures higher than your plants actually require is a waste of both energy and money. Keeping your heated greenhouse frost-free at 3C (37F) is the absolute least, although fragile plants like pelargoniums, half-hardy fuchsias, and citrus trees thrive at 7C (45F) and 10C (50F) (50F).

Keeping young plants and plugs safe at this temperature is also an option. You can overwinter your most delicate plants in a conservatory, if you’re lucky enough to have one. These are plants that can’t tolerate temperatures below 13 degrees Celsius (55F).

Position heaters carefully

In order to keep your electric fan heater away from water, place it in an open area at the end of your greenhouse. In order to avoid drying out plants, angle the heater such that warm air is directed above any neighboring plants.

Only heat the area that you need to

You can save money by establishing a greenhouse within your greenhouse instead of heating your complete greenhouse for a few delicate plants. Divide your greenhouse into sections by erecting a perspex wall or creating bubble wrap insulation curtains to keep your sensitive plants from overheating.

Use horticultural fleece

In really cold weather, cover your plants with a couple of layers of frost protection fleece to provide them with an extra layer of insulation without having to turn up the heat. During the day, remove the fleece from your plants to let them get enough light and air. You can also use a greenhouse cloche to protect the border plants. Alternatively

Don’t forget to ventilate

To prevent the spread of fungal diseases and maintain a healthy growing environment, proper ventilation is vital. By watering plants sparingly and early in the day, you can avoid a buildup of moisture. Open the greenhouse vents on warm sunny days to remove condensation, and remember to close them again before sunset to keep the greenhouse warm during the day.

Heated propagation

In order to ensure that your seeds germinate, get a heated propagator. A windowsill propagator will enough for a few seedlings, but if you plan to grow a lot of plants, you’ll need a heated propagation mat for your greenhouse staging. Cuttings can be rooted in these and seedlings can be kept warm after germination in them.

Why Are Greenhouses Worth the Investment?

Having a greenhouse in the winter can be beneficial to home gardeners. If you’re still not convinced, consider these benefits of investing in a greenhouse:

Extend growing season

There are many advantages to cultivating plants in greenhouses. It is difficult to grow individual plants in Idaho, Oregon, or elsewhere in the Pacific Northwest area because the summers are short and chilly. Even if there is still frost on the ground, you can start planting in a greenhouse.

In addition, it will shield your plants from rain, reducing mildew. Even if the weather is cooler than typical, you can still harvest your crops.

Grow different types of plants

Certain plants can be grown year-round, regardless of the season. Warm-season crops can be difficult to raise if you live in the north of the country. A greenhouse is the only way to grow citrus trees, eggplants, and melons in frigid climates.

You may grow a wide variety of fruits and vegetables in a greenhouse equipped with a heating system and grow lights. To begin planting, you don’t have to wait for the next growing season to arrive. Having a greenhouse is an asset to any gardener, no matter how experienced they are.

Protect plants from wind and precipitation

Even the most delicate plants can be harmed by excessive rainfall. Some of your plants may be bowed to the ground after a strong storm. Even a modest dusting of snow may wreak havoc on a garden full of delicate plants.

A greenhouse is a better option if you live in an area that gets a lot of cold and rain. Insulation, cover, electric heaters, solar heating, and other natural heat sources can be used to manage the temperature of your home. To maintain your greenhouse’s microclimate regardless of the weather outside, you can utilize this method.

How Much Warmer Is an Unheated Greenhouse at Night?

The sun is the only source of heat in an unheated greenhouse, which is also known as a cold greenhouse.

Unheated greenhouses can have temperature differences of up to 30 degrees Fahrenheit from the outside.

Depending on the sort of greenhouse you have and the level of insulation in your greenhouse, this variance might be rather large.

How to keep a greenhouse warm in the winter | Total Landscape Care

A temperature variation of 5 to 10 degrees Fahrenheit is not uncommon in a single-layer greenhouse.

Outside, a 9 to 14 degree Fahrenheit temperature variation is typical for a double-layered greenhouse.

How do Cold Do Greenhouses get at Night?

Temperatures in greenhouses can fall as low as 50 to 60 degrees Fahrenheit at night in the northern United States.

As a matter of fact, in the winter, greenhouse temperatures can fall to as low as 0 degrees Fahrenheit.

Summer nights in the South can bring greenhouse temperatures of 60 to 70 degrees Fahrenheit. Temperatures in greenhouses can fall to as low as 15 degrees Fahrenheit at night during the winter months.

At night, greenhouse temperatures can reach 40 to 50 degrees Fahrenheit in the Mid-Atlantic region of the United States. At night, temperatures in greenhouses can fall to as low as 10 degrees Fahrenheit in the winter.

Do People Normally Heat Greenhouses?

There can be dramatic drops in greenhouse temperatures in the winter and on cold nights.

The growth of plants in greenhouses can be significantly impacted by cold temperatures, which can result in stunted growth. Plants may finally perish in extreme instances.

The ideal temperature for most growers is between 80 and 85 degrees Fahrenheit. It is for this reason that greenhouses are heated when the weather gets too chilly.

Should I Make My Greenhouse Airtight To Preserve Heat?

Airtight greenhouses are essential. During the colder months, heat from the greenhouse will escape and cold air will enter, resulting in a decrease in the temperature within the structure.

So you should make sure that your greenhouse is air-tight. This will keep in heat and preserve it so that your greenhouse doesn’t get too cold for the plants.

The Answer to “How Warm Does A Greenhouse Get During Winter?”

Consequently, it is imperative that your greenhouse is airtight. This will prevent your greenhouse from being too cold for the plants because it will keep the heat in and preserve it.