Updated at: 07-03-2023 - By: Sienna Lewis

It doesn’t matter what the weather is like outside when you have your own little microclimate created in a greenhouse. Greenhouses are useful for much more than just extending the growing season and keeping plants safe from the weather. Even in the coldest months of the year, you can cultivate out-of-season plants all year long.

What Temperature Should A Greenhouse Be In Winter?

A greenhouse’s temperature should be as high as possible. However, you should aim for a minimum temperature of 37 F (3 C) when keeping frost-sensitive plants in the greenhouse. The Greenhouse will remain frost-free at this temperature. Temperatures around 45 degrees Fahrenheit (7 degrees Celsius) are ideal for many plants, including citrus trees.

As the majority of the heat loss occurs through the windows of the Greenhouse the most important thing to reduce this heat loss by insulating the walls. No matter how many layers you have in your Green, it won’t make a difference.

Bubble wrap is the best material for this purpose since it is transparent, light, cheap, and has good thermal qualities. It is also the most effective. As a result of the bubbles, heat transport is greatly slowed. Click here to see the current price on Amazon for this product, which is widely available.

Use clips made for this purpose, such as Creative-Idea 50 Set Greenhouse Support Clips, when fastening bubble wrap to the inside of your greenhouse. Installing these clips is a snap thanks to their special design for aluminum greenhouses with grooved tracks. To check Amazon’s current price, go to this page.

All About Greenhouse Temperature Difference - Krostrade

It may be essential to use adhesive tape to adhere the insulation to the greenhouse roof and walls if your greenhouse does not have grooved tracks. Because of the low temperatures, standard packing tape’s adhesives will not hold up well when used in this manner.

Additionally, you may want to utilize Double Bubble Reflective Foil Insulation on the greenhouse’s north wall while insulating it (assuming you are living in the northern hemisphere). By reflecting the sunlight back through the greenhouse a second time, this material serves as both an insulator and a solar concentrator, extending the life of the greenhouse’s interior walls. This enhances the Greenhouse’s ability to retain heat.

Increasing the greenhouse’s thermal mass is a crucial second approach for retaining heat. The nighttime temperature of the Greenhouse can be raised by placing large, heavy things like brick walls or rocks there. During the day, the sun’s rays heat these items, which then release the heat back into the atmosphere at night. There have been some academic studies that say this can elevate the minimum by a maximum of 3 °F.

Greenhouse passive heating devices can be used in a variety of ways, depending on the design. A concrete slab, a brick wall, or stone or brick for the bottom Greenhouse walls are all examples of how to build a Greenhouse on a concrete slab.

Steel drums or carboys painted black and filled with water can be placed in the greenhouse if none of the above options are available to you, or if you already have a greenhouse in place for this purpose. Steel drums can be used as legs to support benches in the Greenhouse if you are short on space.

Do You Need to Heat a Greenhouse?

It’s a situational thing. Water, sunlight, air, and nutrients are the four primary necessities for plants to thrive. To be healthy, plants use chemical reactions such as respiration and photosynthesis. Your plants require heat/sunlight to accomplish this. Your plants’ growth slows down if the temperature is too low.

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Unheated greenhouses are an option for gardeners in milder locations when winter temperatures drop only little. On days with heavy humidity, the sun may be enough to elevate the temperature, but watch out for overheating.

However, if it’s below freezing outside, even a thin sheet of plastic or glass won’t do the trick. In order to keep your plants happy, you may want to insulate it. Uninsulated greenhouses lose heat at night, even if they receive plenty of sunlight during the day. A heating system may be necessary if this is the case.

How Cold Is Too Cold for a Greenhouse?

You can use a greenhouse as either a hothouse or a cold house since you can establish your own microclimate. With one greenhouse, you can even create two climates.

Heating and ventilating your greenhouse may be preferable in colder climates like Montana and North Dakota. The overnight temperature should not go below 55 degrees F.

You can set the greenhouse temperature to 45 degrees F if you live in a warmer area and prefer a cooler environment. The daytime temperature of your greenhouse should never exceed 90 degrees F.

There are techniques to keep your greenhouse warm in winter, regardless of the weather outside. On the other side, overheating your plants might be detrimental. If the sun is hot, draw a shade over the top of your head to keep it out.

What Are Cost-Effective Ways to Heat a Greenhouse?

In order to keep your greenhouse warm, there are numerous options that are both inexpensive and efficient. Plants need protection from the harsh winter cold because greenhouses, particularly those made of full glass, do not keep their heat in the winter.

Doing so can be done in a cost-effective manner, as follows:


Keeping your plants alive in the cold requires that you insulate your greenhouse. To keep the heat inside, wrap the windows and doors in bubble wrap. In terms of insulation, larger bubbles are better.

Install a cost-efficient heater

If you want to keep your greenhouse warm, you don’t have to spend a fortune. It’s best to have a heater going all winter long to keep your plants warm. A digital thermometer can be used to keep track of and calculate the temperature differential in a greenhouse.


Keep an eye on the airflow in your greenhouse so that it doesn’t overheat.


Shade your plants from the sun if your greenhouse is directly exposed to the sun or if you live in an area with humid summers. Aluminum or wood rollup screens, paint-on materials, polypropylene shade cloth, and vinyl plastic shading can all be used to create a shaded area.

Raise your plants off the ground

Temperatures in the soil are too low for most plants to thrive. You can avoid your plants being affected by the soil’s cold by elevating them above it. Reusing old pots or other containers is an option.

Why Are Greenhouses Worth the Investment?

One of the best investments a gardener can make is a greenhouse. A greenhouse is a fantastic investment for a number of reasons:

Ideal Growing Environment

A greenhouse is the ideal place to grow a wide range of plants, including fruits, vegetables, and flowers, because it maintains a constant temperature and humidity throughout the year.

Customizing your greenhouse will help you grow your plants to their full potential. With a greenhouse, you’ll have enough heat and water vapor to maintain a warm climate even if it’s snowing outside.

Protect your plants

Customizing your greenhouse will help you grow your plants to their full potential. With a greenhouse, you’ll have enough heat and water vapor to maintain a warm climate even if it’s snowing outside.

Grow plants all-season

Customizing your greenhouse will help you grow your plants to their full potential. With a greenhouse, you’ll have enough heat and water vapor to maintain a warm climate even if it’s snowing outside.

It is possible to personalize your greenhouse so that your plants can thrive in it. It’s possible to keep a comfortable temperature inside a greenhouse even while it’s snowing outside.

Greenhouses in the desert: Are they useful? | Home + Life + Health | tucson.com

Maintaining a Greenhouse Temperature Difference Won’t Burn a Hole in Your Pocket

Keeping a greenhouse temperature differential under control doesn’t have to be expensive. The following hints can help you prepare your greenhouse for spring planting or even winter gardening.

Growing-on at Cooler than Optimum Temperatures

In an effort to save money this spring, many farmers are considering lowering the temperature of their greenhouses during the growing-on stage of production. Understanding how temperature impacts everything from scheduling to insect control to flowering and plant quality is critical. Some plants are able to thrive in cooler temperatures, whereas others are unable to develop at all and remain inactive. This has to do with the ideal temperature at which different species of plants grow best.

Optimum Temperature

When the temperature of a plant drops, there is a point at which the plant’s growth and development halts.’ This temperature is known as the “base temperature,” and it varies greatly among plants. ” A plant’s growth rate increases as the temperature rises above the base temperature, reaching a point where it can no longer grow. Temperatures in this range are ideal for most plant species, but they might vary considerably among them. Warmer-climate plant species are more likely to have higher optimum growth temperatures, while cooler-climate species are less likely. The pace of plant growth slows down as temperature rises above the optimum. For this reason, it’s difficult to raise diverse plants with various heat requirements in the same greenhouse: the optimal temperature for each species differs. Temperatures that are ideal for one crop may be detrimental to another. Some considerations to keep in mind when using less-than-optimal temperature regimes for spring crops are outlined below.

Seed Germination

Seed germination is slowed down, the germination percentage is reduced, and the germination uniformity is reduced when temperatures are too low during the germination process. For most crops, the ideal germination temperature is 72F to 76F. The majority of plants can survive temperatures that are below ideal after they have become established. When it comes to seed germination, saving a few degrees is not an option.


Reduced greenhouse temperatures will lengthen the time it takes to produce and blossom. As a result, fewer crops may be grown in the spring in the same amount of space. Plants will take longer to flower, and the amount of money spent heating each crop may increase if the outside weather is bad.

Flowering time increased when temperatures fell, according to research from the University of Minnesota. When it came to the length of time it took for a plant to flower, it depended on the type of crop. ‘Super Elfin Lipstick’ impatiens, for example, increased flowering by 18 days if the temperature was lowered by 7°F. Petunia ‘Purple Wave’ delayed flowering by 33 days when the temperature was lowered by the same amount. Because of this, the flowering of ‘Purple Wave’ petunia was delayed by an average of three days for every 1°F drop in temperature. Listed here are a few examples:

Plant Quality

Some crops may actually benefit from lower temperatures, despite longer production times. When plants are kept cool, they often produce more branches, larger flowers, and more flowers per plant. For example, in a study by the University of Minnesota, temperature fall from 77 to 59°F enhanced lateral branching, blossom number and bloom size for fuchsia ‘Dollar Princess.’ New Guinea impatiens, on the other hand, thrive at warmer temps. According to one study, cooling New Guinea impatiens to just 59°F nearly prevented flowering.

Water uptake and Nutrition

The uptake of water and nutrients is slowed by the use of cold media. When the temperature is lower, plants, benches, and floors remain moist longer after each watering. Foliar illnesses like Botrytis become more likely when humidity and condensation rise.

As a preventative measure, crops should be extensively examined to identify their irrigation requirements. Water usage will drop when the temperature drops. Make sure that your irrigation is set to start at 10 AM and complete by noon, if you can do so safely. When water is supplied to the growing media too early in the day, the temperature of the medium will continue to drop. This is crucial for growers who rely on cold water.

This includes monitoring the EC and pH and adjusting fertilizer concentrations as necessary. Plants receive less fertilizer because of the decreased frequency of irrigation.

Pest Management

Manage the relative humidity levels by ventilation and heating in order to prevent Botrytis and other foliar diseases. The usage of HAF fans in greenhouses will help to maintain a consistent temperature and prevent condensation.

It is possible that Botrytis and Powdery Mildew preventative fungicide applications are required in a colder greenhouse.

Root rots produced by Pythium, Rhizoctonia, and Thielaviopsis are more likely to occur in cool media. Monitor the health of the roots on a regular basis and use fungicides as soon as illness appears. In cold media, fungicides will take longer to take effect. Apps can either take longer to show effects or be less effective.

Insect and mite life cycles are slowed by cool temperatures, which may necessitate fewer pesticide applications early in the crop cycle. Aphids, mites and whiteflies can arise out of nowhere when the weather warms up in spring, so keep an eye on your plants for these pests. Early in the production cycle, and throughout the growing season, keep an eye on crops.

Plant Height

Plant growth is slowed by lower than ideal temperatures, which affects both timing and size. If you want to grow your plants at a lower temperature, it’s likely that you’ll want to lower the nighttime temperature. The elongation of stems is influenced by the temperature differential between day and night. In general, the higher the temperature difference between day and night, the greater the height of your crop. That means that plants will grow taller if the nighttime temperature is lower and the daytime temperature is higher.

Tips for Growing Cooler

Prior to reducing the temperatures in a greenhouse in early spring, categorize plant species into warm and cold crops depending on their temperature requirements.

A few warm-weather crops cannot be grown at temperatures below their optimum (65-68F nights). In addition, there are alternanthera, New Guinea impatiens and lantanas as well as vinca and celosia as well as cleome and coleus.

Cool-season crops include alyssum, alyssum dianthus and pansies as well as osteospermum and osteospermum. The quality of these crops is unaffected by less-than-optimal conditions, but the time it takes to produce them is greater than it would be if they were produced at optimal temperatures.

Plants that have developed a strong root system are better able to withstand the drop in temperature. Start growing as soon as possible at a temperature that promotes rapid establishment of the roots. It’s safe to lower the temperature on newly transplanted plants when they’ve established roots and begun to fill out (2-3 weeks).

Avoid placing pots directly on the ground in the greenhouse in order to maximize the utilization of the greenhouse’s heat. Air temperatures can be 10-20 degrees Fahrenheit lower than those on the ground (unless bottom heated). When plants are placed on the floor of hoop houses that have been unheated for the most of the winter, this problem can be exacerbated. Under certain circumstances, air temperature differences of more than ten degrees Fahrenheit can develop between the benches and the eave.

The grower should be aware of the many environmental conditions that exist in their greenhouses, especially in extreme weather circumstances. In greenhouses, digital thermometers can be used to measure air temperature at various heights, at various places in the greenhouse, and under various external conditions. Use this information to plan crop placement based on temperature requirements and to locate chilly spots that may require horizontal airflow fans. Soil thermometers can also be used to monitor the growing media’s temperature. Growers that use bottom heat systems to keep their media and roots at the proper temperature are better able to flourish in lower temps.

Many gardeners are able to effectively cultivate a variety of crops in a greenhouse at temperatures that are below optimal year after year. As much as feasible, growers match the crop’s temperature needs to the location’s temperature variances. It has come to their attention that the quality of the crops could suffer as a result. Individual circumstances and all relevant variables should be taken into account while deciding whether or not to grow cool.

Efficient Greenhouse Design - Greenhouse Product News

Periodically Reducing Greenhouse Temperature and Minimizing Supplemental Light

Yes, growers can turn off supplemental lighting (other than for photoperiodic or day-lengthening purposes) on cloudy, chilly days to save energy. Up to seven days a week can be used in a USDA-ARS greenhouse in Toledo, Ohio, with minimal affect on the plant’s timing and quality. Petunia ‘Supertunia Vista Bubblegum’ and ‘Supertunia Mini Strawberry Pink Veined,’ angelonia ‘Angelface Blue,’ lantana ‘Luscious Citrus Blend,’ snapdragons, and dianthus ‘Telstar Pink,’ were used to demonstrate this. Plants were moved from a normal winter/spring greenhouse environment (72F day/65F night), 300 molm-2 Angelonia, on the other hand, had a six-day delay in blooming. On one or two days every week, producers can reduce the greenhouse temperature, close the shade curtain, and switch off the additional lighting if the weather forecast calls for it to be chilly and gloomy. If you wait any longer, your flowers will be delayed and your growth will be slowed. The testing of more crops requires more research. See the following article for further information: Reduce Greenhouse Energy Costs with a New Approach. Lowering the temperature of the greenhouse may lead to an increase in the relative humidity, which could lead to an increase in the prevalence of Botrytis and other leaf diseases.

How To Heat Your Greenhouse In Winter?

If the temperature in your Greenhouse continues to fall below the acceptable level despite the application of insulation and passive heating methods, external heating may be necessary. For the Greenhouse, it’s crucial to choose a heating unit that can withstand the humid conditions, so it can survive for a long time.

To prevent temperatures from dropping below 37°F (3°C), a thermostat is essential, as is turning the heater off when the room is warm enough to reduce the heater’s operating expenses. Many heaters on the market claim to have a built-in thermostat. In most cases, the temperature can only be set by turning a dial.

Both a heater and a thermostat are required if you want to set the temperature reliably and precisely. The Greenhouse is a damp area where water is employed, so it is important to select components that are specifically built for this environment.

The Palma Greenhouse Warmer and Digital Thermostat, seen in the image below, is considered the best option for this application because it includes both the heater and the thermostat in one convenient package.

The heater and heating elements on these devices are made of stainless steel, making them corrosion-resistant. Additionally, the heating unit’s bearings are made to withstand humid conditions.

For usage in a greenhouse, the Thermostat unit is also water-resistant. An additional feature of the Thermostat is an external sensor cable for measuring the ambient temperature, which can be placed separately from the Thermostat for the best possible temperature reading. In addition, a digital display allows you to adjust the temperature from 0°F to 90°F to meet your specific needs.

The heater can heat a greenhouse up to 120 square feet (12 square meters), which is a typical size for a greenhouse in a home.

Why Are Greenhouses So Much Hotter Than the Air Ourside?

Greenhouses are warm, protective environments where you can start seedlings, grow frost-tender plants and raise a tropical succulent garden, even if you live in a cool region. Gaining an understanding of how greenhouses work will allow you to get more from your time spent cultivating your plants indoors. You may also use it to properly heat and cool them to the temperatures you desire.

Radiation Types

With the right greenhouse, you can sow seeds and cultivate frost-tender plants as well as a tropical succulent garden regardless of your location’s climate. When you know how greenhouses work, you’ll be able to get the most out of them. Also, you can use it to efficiently heat and cool the items.

Air Mass

greenhouses are far more efficient at concentrating heat from sunlight because of their smaller air masses compared to those of the surrounding environment. On a sunny day, the same logic determines how hot the car’s inside gets. A car’s air mass heats up significantly more quickly than the air around it because of its smaller size. In addition, this phenomenon explains why the planet warms when the atmosphere contains more compounds that block thermal radiation from reaching the ground.

Construction Materials

Regardless of the specific design of a greenhouse, the basic idea of retaining heat is the same across all of them. Wood, aluminum or polyvinyl chloride pipes are commonly used to build greenhouses’ frames, which are supported by glass or plastic panels. Glass, fiberglass, stiff double-wall plastics, or film plastics can all be used to cover greenhouses for various purposes. However, classic glass greenhouses require significantly more sturdy frames than heat-trapping materials that use alternative methods.

Location Effect

The location of a greenhouse can impact its temperature. Running a heater or air conditioner in your home will cause it to get hotter and colder outside. While the greenhouse’s inside heats up during the day, it doesn’t insulate well on a cold night because of its plastic and/or glass. Using a 220-volt heater to supplement the greenhouse’s natural heat during the cold months may be important. You can reduce the temperature inside your greenhouse by using fans and/or leaving the doors open on hot summer days.


What is the temperature difference in a greenhouse?

Temperature differences of 5 to 10 degrees Fahrenheit are typical in a single-layer greenhouse. Outside, a 9 to 14 degree Fahrenheit temperature variation is typical for a double-layered greenhouse.

How much does a greenhouse increase temperature?

A single layer Greenhouse is often 5 to 10 degrees cooler than a double layer, while a double layer is typically 9 to 14 degrees cooler than a single layer.

How do greenhouses regulate temperature?

You can prop open the roofs of some greenhouses to prevent the buildup of hot air in high temperatures. Using polyethylene walls and roofing, greenhouses and hoop buildings can be ventilated by rolling up the plastic sheets.

How much warmer is an unheated greenhouse at night?

Using an unheated greenhouse will keep plants frost-free in all but the worst of winters, even if the temperature drops to minus 5°C overnight. As a bonus, it will keep the plants dry, which is essential for their survival. Plants in the dry are far less prone to freeze than those that are wet.

Does a greenhouse stay warm at night?

During the day, a standard greenhouse traps solar heat, keeping the plants warm at night. However, frost damage might occur in the greenhouse without additional protection when the nights are particularly cold.

What is the minimum temperature for a greenhouse?

Depending on how you intend to utilize it throughout the year, a greenhouse can be either a hothouse or a coolhouse. The minimum nightly temperature for a hothouse is 55 degrees Fahrenheit, whereas the minimum for a coolhouse is 45 degrees Fahrenheit.

Will plants freeze in a greenhouse?

Keeping your greenhouse warm in the winter without spending a fortune or harming the environment is possible with these simple techniques. The question is whether or not heating is necessary. Tender plants will be harmed if temperatures outdoors dip below 0 degrees Celsius, making a cold greenhouse an unworkable option.

How do I make my greenhouse warmer?

When it comes to keeping greenhouses warm in the winter, a simple solution is to add thermal mass or heat sink. They’re things that take in heat during the day and release it at night. Adding a few degrees of heat can make all the difference in the world.

How much warmer Do greenhouses stay?

Proper greenhouse insulation can keep the temperature in the greenhouse 30 degrees Fahrenheit higher than outside. If you have a greenhouse, you can keep it running in the winter at -17 degrees Fahrenheit before the air in your greenhouse hits the frost zone.


Information about the Variation in Temperature in a Greenhouse