Many new greenhouse gardeners are concerned about how to maintain a warm greenhouse in the cold. Inexperienced greenhouse gardeners frequently ask this question. In the end, who doesn’t want to make certain that their plants are kept in a temperature-controlled environment?
- When to Start an Outdoor Mini Greenhouse in Northeast Iowa? Helpful Information!
- How Far Apart To Plant Jalapeno Peppers? Perfect Information For You
- How To Grow And Pick White Eggplants? Comprehensive Guide
- How To Dye Orchids Blue? Choosing A Dye For Coloring Orchids
- Ultimate Guide to Choosing a Best Flowers To Grow In Colorado
Check out some of the most frequently asked greenhouse gardening questions and answers here.
Why Heat A Greenhouse?
It’s critical to have a warm greenhouse, especially in the winter. Artificial heat is required when temperatures fall below freezing, even if the sun is shining, to keep the plants in good condition in a greenhouse.
In addition to water, sunlight, and carbon dioxide (CO2), plants also need a temperature that is just right for their growth. When growing plants that need a warmer temperature in the winter, you’ll need to employ heating technologies to keep the greenhouse warm.
You need to maintain the plants warm so that they don’t freeze and have enough energy to succeed in the greenhouse. A greenhouse can be heated in a variety of ways. Here is a list of each of them, in no particular order. It’s up to you which method of greenhouse heating works best for you.
Types Of Heating Methods
The first step is to select Compost.
Gardeners who have worked in the field for a long time are familiar with the benefits of a compost pile. Smoking hot, it’s a great technique to raise the temperature inside the greenhouse while using less electricity.
In the heart of the pile, the compost can reach 150 degrees Fahrenheit, which naturally distributes heat and keeps the greenhouse warm. Wood mulch can be used to build walkways. Mulching the beds might increase the temperature in the garden.
Make use of double-paned windows.
To keep the sun’s rays from escaping, double-pane windows are a good choice for homes. There is no heat loss because they are energy efficient.
A double-pane window is understandably pricey, but if that’s the case, clear plastic can provide the same impression for a fraction of the price. Once you caulk it, the heat will be sealed and you’ll be good to go.
Using the Sun as a source of heat.
The heat from the sun is available for free. It’s also used as a greenhouse heating source. The sun’s electromagnetic radiation is believed to heat the greenhouse’s thermal mass, as well as the greenhouse itself.
Heaters powered by electricity
The cost of heating a tiny greenhouse may not be prohibitive. An electric heater with a thermostat is the finest option for keeping the interiors warm. If you want a more hands-off approach to heating, this technique is ideal for you.
Install the heater inside the greenhouse, then simply set the thermostat to your desired temperature and sit back and relax while it does the work of keeping the greenhouse toasty. These heaters are now equipped with an automated shut-off feature.
You won’t have to be concerned about overheating the space.
Using Thermal Mass Objects as an Alternative
In greenhouses, there are numerous items that aid in the efficient use of heat. During the day, they collect solar energy and store it in their bodies as body heat. When temperatures dip at night, they release their heat. As a result, they are called thermal mass. It is possible to use items like bricks and rocks as they absorb heat and are useful in colder weather.
As a thermal mass, water is ideal. Bricks or stones can be used to build raised beds. According to legend, they have a high capacity for heat absorption. Black buckets of water can also be used to keep the area warm.
Insulating the northern side of the house
Insulating the northern side of your home with thermal insulation foil is a good idea. As a result, the greenhouse is protected from any heat loss and the north winds are prevented from entering.
A thermal mass heating system also makes it easier to take in the sun’s rays. Only the northern side of the greenhouse should be made of glass.
Bubble Wrap Insulation
Rather than packaging-grade bubble wrap, use horticultural-grade bubble wrap to insulate. They’re more durable and can survive the damaging effects of the sun’s ultraviolet rays.
It is easier to insulate with large bubbles, which also provide the greatest light to the plants. The bubble wrap can be stapled or taped in place. Keep the windows clean to minimize light loss.
Outdoor plants can also benefit from bubble wrap insulation. Cold weather is no problem for them, since they keep them from freezing and fracturing as well.
Opt for Battery-Powered Heated Mattresses
Solar water heating pipes are an alternative to other methods such as using compost in the greenhouse or heating water in barrels. Close the loop on these so that hot water is pumped through the beds of the garden.
Using these pipes around the compost heap is possible. The water moving through the pipe will be heated by the temperature, and the soil in the beds will gradually warm up as well.
Even if you don’t have an electric greenhouse, you can still keep your plants warm enough to cope with changing weather conditions.
These were some of the most common means of heating. However, to find out the best way to heat your greenhouse, keep reading.
Best Way To Heat Greenhouse
This is a list of some of the most commonly used heating methods. For the most effective method of greenhouse heating, continue reading.
A more effective approach to heat your greenhouse if you have a larger one and live in an area with severe winters is by first insulating the floor and then using compost and water pipes to warm the soil. Heaters with a high output or even many heaters are required in large greenhouses, and this can be an expensive undertaking.
How To Heat A Small Greenhouse With Heaters
Simply putting in a heater of the right capacity in the right spot can work wonders in a small greenhouse.
Electric heaters eliminate the need for any additional system, regardless of the location or orientation of the greenhouse. Even if electric heaters are a costly alternative, there are a variety of other choices.
While looking at other greenhouse heating alternatives, especially for a smaller area, these all utilize some sort of fuel. This is where the following heaters come in.
For example, propane or natural gas heaters are utilized in greenhouses and do not require power. As a result, even if the electricity goes out, your plants will still have access to the greenhouse’s heat.
If the greenhouse is 150-175 square feet or less, it’s best to utilize one heater, according to experts. A 200-square-foot one is within reach for those living in more temperate climates.
A propane heater in the greenhouse can be heated using gas tanks you possess. Propane must be properly ventilated to remove gases and provide an adequate amount of oxygen for optimal combustion.
The usage of paraffin heaters to heat greenhouses is also an excellent idea. They function by lighting a wick and allowing it to suck liquid from the storage containers. While these heaters do emit harmful air pollutants, they can only be used in areas where there is enough ventilation.
Paraffin greenhouse heaters have a number of advantages. In addition to being reasonably priced, they are also available in a variety of sizes.
These heaters have reduced operating expenses. These pieces of equipment don’t necessitate a lot of maintenance. A plant’s health improves as a result of the CO2 it produces.
Because they don’t require an electrical supply, paraffin heaters are also self-contained.
Does a Greenhouse Need to Be Heated?
If you reside in a cold climate, you’ll need to insulate your greenhouse.
Is an Unheated Greenhouse Frost-Free?
No matter how cold it gets outside, there’s no guarantee that plants in an unheated greenhouse won’t freeze.
How Do You Keep a Greenhouse Warm?
If you insulate your plants with bubble wrap, use a thermostat, use heaters, ventilate your greenhouse, circulate air, or keep your plants off the chilly ground, you can keep them warm throughout the cold winter evenings. Better insulation can be achieved with larger bubbles in bubble wrap. Maintaining heat in the greenhouse is critical, so make sure that all of the greenhouse’s windows and doors are properly covered.
The KlimaHeat is a wonderful choice if you want to utilize heaters because it heats up immediately. A thermostat is the greatest way to keep an eye on the greenhouse temperature. Maintain a temperature range of 24 to 28 degrees Celsius (75.2 to 82.4 degrees Fahrenheit).
Using air circulators to evenly warm the air in your greenhouse is the best method to avoid cold and hot spots and inaccurate temperature readings. While you’re at it, open the greenhouse vents to let fresh air in and keep mildew, mold, and fungus from growing. Before you go to sleep, close the vents to keep your plants warm.
Is Greenhouse Gardening Worth the Investment?
That’s for sure. If you want your fruits, veggies, herbs, and flowers to thrive, you need to cultivate them in an area that is free of pests and disease. Investment in greenhouses may necessitate an initial outlay, but you’ll get back more than you put in.
The following are some of the finest reasons to invest in greenhouse gardening:
It protects your plants from inclement weather
In the event of torrential rains, blizzards or hailstorms or any other harsh weather conditions that could harm your delicate plants while they are in the greenhouse, you can rest easy. You won’t have to worry about making emergency plans to protect your plants from adverse weather, unlike typical outside gardeners.
You’ll eliminate the need for a garden shed
Additionally, greenhouses can be used to store everything you need to grow plants, from seeds to tools and equipment to accessories. A garden shed isn’t necessary!
It keeps the beneficial bugs in and the destructive ones out
Because greenhouses give you complete control over what enters and exits, you have the choice of allowing some helpful insects into your plants’ environment. Insects like bumblebees, ladybug parasites, nematodes, beneficial nematodes, fly predators, leafminer parasites, mealybug destroyers, whitefly parasites, thrips predators, spider mite predators, soldier bugs and praying mantis, moth egg parasites, and many others are included.
A greenhouse, on the other hand, can be used to keep pests and animals at bay. There are a wide variety of pests that could be found in your garden, including cabbage maggots and cutworms, Colorado potato beetles, Mexican bean beetles, flea beetles and tarnished plant bugs as well as Japanese beetles.
Save money on grocery shopping
Your favorite fruits, veggies, and herbs will be available year-round thanks to your greenhouse’s ability to cultivate them. There will also be no fluctuation in fresh food pricing caused by shipping costs and weather conditions. The best part is that you’ll be able to spend less money at the supermarket.
You can extend the growing season
Having a greenhouse means that you may easily extend the growing season of your crops. Keep in mind that you have complete control over the temperature and humidity conditions in your greenhouse. Regardless of the season or weather, you can use this method to maintain a consistently warm and humid growing environment for your plants.
You’ll get to grow more plants
Using a greenhouse, you may easily cultivate plants that aren’t native to your region or that aren’t in season. It’s possible to cultivate tropical fruits and vegetables in a colder climate thanks to a greenhouse.
Do You Need To Heat Your Greenhouse In Winter?
The decision to add extra heat to your greenhouse is one you should think about carefully before making.
The heating of your greenhouse in the winter is not required in some areas of the country.
It’s winter, and your nighttime temperature rarely goes below 30 degrees. It is possible to cultivate a wide range of cold-tolerant vegetables in your greenhouse from now until spring without doing any additional labor.
In contrast, no matter how tough your crops are, you will need to add some type of additional heating if you have a harsh winter with temperatures routinely falling into the single digits or lower.
Of course, if you want to grow warm-season veggies in your greenhouse in the middle of January, you’ll need to employ a combination of the techniques listed here. Even if you reside in a more temperate region, this holds true.
8 Practical Greenhouse Heating Options
It’s time to start thinking about how to heat your greenhouse once you’ve determined whether or not it’s necessary given your climate and growing objectives.
All of the solutions below are doable (i.e., they won’t take a lot of time and effort on your behalf), but their cost and environmental impact vary widely. In each part, take a moment to think about whether or not it’s in line with your long-term goals.
Solar panel-powered heaters and passive solar capture are two ways to use solar energy to heat greenhouses.
Solar Powered Heaters
They’re exactly what they sound like: little solar-powered heaters.
Unfortunately, you’ll have a much harder time finding one of these heaters. Heaters utilize a lot of energy, which means that several solar panels are needed to power them.
Installing fifteen 100-watt solar panels, for example, would be necessary to power a 1,500-watt heater. Putting that many solar panels on your greenhouse would make it impossible for light to get through.
You’d need three 500-watt solar panels even if you sized up and bought the more costly ones. That’s a lot of panels for a greenhouse roof.
Unless you already have solar panels on your roof to power your entire house, a solar-powered greenhouse heater will be out of the question for the majority of gardeners.
Passive Solar Heating
However, don’t underestimate the sun’s value just yet.
Grow crops all year round by using passive solar heating in a greenhouse, one of the cheapest methods.
It was just 42 degrees outdoors when my greenhouse reached 101 degrees. A lot of excess heat is generated without any effort. In the depths of winter, you may grow nutritious vegetables without increasing your electricity cost by capturing and redistributing heat.
Raised soil beds, stone or brick walkways, and huge flat boulders can all help your greenhouse retain more heat during the day, allowing it to produce more food. Large water tanks or jugs can also be used to capture heat.
Evening temperatures will cause these surfaces to begin releasing this heat back into the atmosphere.
Adding a heat sink to your passive solar design is another way to take advantage of the sun’s energy.
To achieve this, excavate a two- to three-foot-deep trench in the middle of your greenhouse. Just around a third of the size of your greenhouse is an ideal size for heat sinks. For a 10 by 10 sq ft greenhouse, for example, a 3 by 3 sq foot hole will suffice.
Add pebbles, gravel, bits of concrete or brick backfill to the hole to make it stable and watertight. All day long, these high-thermal-mass fabrics will keep you warm. Heat is subsequently dissipated overnight by means of the tube.
Earth-source heat pumps are those that circulate air into and out of the ground while utilizing a solar fan or pump as a heat sink.
Hot Water Heating
In addition to using the sun’s free energy, you may heat your greenhouse with hot water.
Heating coiled water lines with solar water heating cells makes use of the sun’s energy. The hot water is collected in a large barrel in the greenhouse via these water lines. As a result of the heat emitted from the water container, the greenhouse’s air gets warmed.
It is also possible to heat the soil directly by installing hot water lines in the flower beds.
In order to keep your greenhouse warm, a water pump circulates water through the solar panel.
Boilers, wood stoves, and electric heaters can all be used with solar water heaters. Even compost bins can be used to store coiled water lines. Decomposition generates enough heat to warm water lines and even a small greenhouse.
It may take some time and money to get this form of heating up and running, but it’s worth it in the long run. However, simple solar choices are also available for those who don’t have a lot of money.
There are various basic choices available to you if you are ready to pay to heat your greenhouse. Electric heaters, like this greenhouse heater from Bio Green, are the most efficient of all options.
You’ll need a power source in your greenhouse if you’re going to use an electric heater.
This heating method takes almost no time at all if you have access to an electrical outlet or a long extension cord. However, keep in mind that greenhouse heating is inefficient.
When it comes to greenhouses, they are designed to optimize the amount of light that can reach the plants within. Insulation is often sacrificed in the process. That explains why greenhouses cool off so quickly at night. The structure of a greenhouse has very little to do with retaining heat.
As a result, using a greenhouse to heat the air is the most inefficient method. An electric heater will run continuously if the outside temperature is below the set temperature, so plan accordingly.
However, this is still one of the simplest ways to get things done. If you live in a place where the weather rarely dips below freezing, this is an excellent choice.
Oil Filled Heater
For a greenhouse that needs to be kept warm throughout the night and on cloudy days, oil-filled heaters are a more cost-effective option than electric heaters.
These heaters, like electric heaters, need a power supply to operate. Heating the oil reservoirs requires electricity. Oil heats up the entire apparatus as it circulates through it. Convection is used to move this heat into the atmosphere.
Using an oil heater instead of an electric heater has another benefit: it doesn’t dry out the air.
It is important for plant growth to have a steady supply of humidity in a greenhouse. Blower-powered electric heaters tend to dry up the air, resulting in lower humidity levels in the room. In contrast, an oil-filled heater warms the greenhouse with convection heat, which has a negligible impact on humidity.
There is no substitute for kerosene if you don’t have electricity in your greenhouse. For the most part, these machines are solely powered by a kerosine tank that can be refilled. There’s no need for outlets or extension cords.
They can dry out the air in the same way as electric heaters. In the winter, your greenhouse’s heaters, whether electric or gas, will have to work virtually nonstop to maintain a constant temperature. Kerosine, on the other hand, is less expensive than electricity.
The heat produced by these heaters is concentrated very adjacent to the flame source, where it is most effective. Kerosine heaters can melt if they are placed too close to a polycarbonate or PVC sheet wall.
Always set your heater in the middle of the greenhouse, away from plants and other combustible objects, for the sake of safety and efficient heating. More information about kerosene heater safety can be found here.
Use Germination Mats
Using germination mats to heat a greenhouse is an excellent option. Similar to heating pads, these mats are used to treat aches and pains. Although they are not capable of warming the air, they can be highly useful for heating the soil to promote greater root growth, especially during germination..
Heating in-ground or raised beds with germination mats is not possible. For huge pots, they aren’t a good option at all! For seedling trays and shallow pot heating trays, however, they’re a great fit.
You’ll be able to change over your beds more quickly if you plan to cultivate cold-season plants throughout the winter by using these mats. During unexpected cold outbreaks, you can also use them to preserve tiny flats of flowers and greens from freezing.
If you’re looking for a germination mat with a programmed thermostat, go no further than Vivosun’s mat and thermostat package. These varieties allow you to control the temperature of the soil to your exact specifications. You can use the mat in the spring to germinate hot-season vegetables that have specific temperature requirements, as well as for resisting the variable winter temperatures.
It’s not as if we’re saying you should bring a cow into your greenhouse at night to keep it warm. Though, if you can keep Bessie from eating your plants, that would be a good idea.
We’re talking about building a greenhouse that can also serve as a home for tiny animals. Even if the two structures are separated by just a few feet, it is possible to keep the temperature of your greenhouse and your poultry coop or pig house stable overnight.
As well as their body heat, the animals’ excrement will also assist keep things warm. A greenhouse can function as a heat source for an animal enclosure already warmed with bulb heaters or other forms of heaters, increasing your efficiency even further.
It all depends on what kind of animals you have, as well as how well your coop and greenhouse are organized.
Use A Hotbed
Planting beds can be turned into hotbeds in the winter to keep your greenhouse warm for free.
Decomposition heats the soil in hotbeds, allowing plants to thrive in it. In-ground beds necessitate digging in order to build these, but the return is well worth it. By using raised beds, you can completely avoid having to dig anything up.
If you’re working with an in-ground bed, you’ll want to add two to three feet of horse dung and straw to the bottom of it. A mixture of decaying leaves, food scraps, and other green stuff can be substituted for horse manure. When establishing a simple compost pile, use the same ratios.
Add six inches of potting soil to the top of the bed and plant your vegetables.
Winter will continue to degrade the manure or compost combination in your garden. Roots will remain happy and healthy as a result of this heat rising through the soil. Even the air around the plant’s leaf will lose some of the heat.
Other Greenhouse Heating Considerations
It’s possible that only a few of the above methods for warming a greenhouse will be effective. There are things you can do to improve the effectiveness of any approach you select.
To maximize greenhouse heating potential, here are a few extra things to keep in mind.
People know that heat rises. If you have plants on the ground, this is exactly what you don’t want to happen in the winter. Not to mention that greenhouses’ ceilings are where the greatest air leaks out of the building. In order to make the most of the warm air you’ve generated, you must maintain it closer to the surface of the ground.
Air movement is the key to accomplishing this.
Fans placed at the roof of your greenhouse can assist drive rising warm air back down onto the plants before it has a chance to cool or depart..
Air that moves too quickly cools rather than circulates; this is undesirable. If you want to create a mild breeze, but one that doesn’t feel cool to the skin, turn your fans down.
If your plants are located near the greenhouse’s walls, this can be a beneficial thing, as it can help to level out pockets of cold air.
Choose a solar fan with batteries that can run overnight on energy generated during the day to avoid adding to your power bill, such as this simple Eco House solar fan kit.
Grow The Right Plants
The most important thing you can do to make the most efficient use of the heat you generate is to choose the correct plants. Tomatoes and peppers, which are summer annuals, need a lot of heat to thrive. If you want to grow them in the winter, you’ll need extra light.
Heating and lighting costs will go up as a result of this.
As an alternative, try to find plants that do better in cooler climates and with less light.
Low temperatures are no match for cool-season plants, which thrive even in the shortest days of the year. Using the methods given above, you should be able to successfully cultivate these types of plants all the way through the winter in most climates.
Some of the most cold-resistant crops to grow in a winter greenhouse include:
- Onions of the green kind
- Onion bulbs
- Greens such as collards
- Asparagus chard
- There are several varieties of Brussels sprouts
Choose frost-tolerant cultivars of these vegetables if you want to get the best results.
Use Thermal Mass
Thermal mass is a method of utilizing solar energy, as we discussed before. Heat retention can be maximized through thermal mass, which operates in a variety of ways.
Heat that would normally be lost when heating your greenhouse with an electric or kerosene heater can be captured by increasing thermal mass in the inside. Running these expensive heaters less frequently will save you money in the long term.
Thermal mass, on the other hand, may absorb and store heat from a variety of sources, including hot water heaters and cattle. Even hotbeds give off heat that can be reclaimed by nearby stones or water jugs.
Here are a few elements you might want to consider including in your greenhouse in order to aid in heat capture and temperature regulation:
- Blocks of cinder
- Water crates or jugs
Building raised beds with extra soil, laying bricks instead of planks to line beds and putting water jugs in your planting beds are all strategies to maximize the use of thermal mass materials.
Insulate Where Possible
Lack of insulation is a major factor in the high energy costs associated with heating a space that can reach temperatures up to three times higher than the ambient temperature throughout the day.
When it comes to light, there’s a purpose for this lack of insulation: it lets in a lot of it! You may still do certain things to help your plants retain heat without sacrificing the amount of light they receive.
Only the southern side of your greenhouse receives any of the sun’s rays. Insulating your greenhouse’s northern walls does not change the amount of light that your plants get.
Build a strong wall on the northern side of your greenhouse if at all possible. However, the majority of greenhouse kits are constructed with a transparent design. Use styrofoam panels or bubble wrap on the north side of your greenhouse if it is the later type.
Reflection from the chilly northern walls back to your plants is made easier by using white or bright surfaces. White should be the color of any solid walls in this area. Choose a lighter color or a reflective substance for additional forms of insulation.
Insulating the walls isn’t the only way to keep the cold out; you should also seal and conceal any gaps around doors, windows, and vents.
Insulating your structure’s walls may not be as effective as insulating the soil, which has a naturally high thermal mass. As the air cools, the heat held in the soil will be less likely to escape.
Mulch is a simple and effective method of protecting your soil and the plants that grow there from the elements.
A variety of mulches are available, some of which are more effective in insulating the soil than others. Because it’s so effective as an insulation and so readily available in the fall, straw is an excellent choice. The use of cedar bark mulch as a summer pesticide is also prevalent.
It’s possible to save money by making use of natural resources like fallen leaves, grass clippings, and evergreen branches.
Row coverings are another option for insulating your soil. Row coverings, unlike mulch, allow the soil’s heat to radiate up to the leaves of your crops.
Woven fiber sheets are commonly used as row coverings because they are thin enough to let sunlight through but thick enough to keep warm air trapped within the fabric. As an alternative, various materials can be employed.
The bottoms of gallon milk jugs can be removed and used to cover smaller plants; five-gallon buckets, which are transparent, can be used to cover larger vegetables. When it comes to covering huge areas, plastic row covers work great.
These row cover materials, in contrast to conventional ones, do not allow moisture to escape or air to circulate. Keep an eye on your plants to make sure they aren’t getting too saturated, as this might lead to fungal development issues. This can be avoided by removing the plastic covers on hot days.
Best Energy-Efficient Heating Method For Larger Greenhouses
Compost heating is a considerably more cost-effective and energy-efficient solution for larger greenhouses.
Compost bins and trench composting are also viable options for assisting in the process of warming the affected areas. The gardener is able to keep the heat on during the winter months because of this.
Using this strategy, gardeners may ensure that their plants will grow throughout the year at a low cost. The way, you ask? Here’s how I’ll explain it.
Two empty barrels can be used to heat the greenhouse with the compost. It will provide the necessary warmth for the plants. Keep 55-gallon barrels a few feet apart in the greenhouse. Make sure you’ve covered all of them before moving on. Allow ample room for the compost by using a metal wire bench to support the barrels.
Fill a wooden box with compost and lay it between the barrels. When it begins to deteriorate, fully load it and boost the temperature. Compress the new compost bin by stepping on it with rubber boots or pressing it down with gloves after adding water. The greenhouse benefits from the heat generated by compost. On top of this, you can set the plants because they will begin to absorb heat.
A thermometer can also be used to check the temperature.
Solar water heating pipes are another option. As a bonus, they’re useful in and around the compost heap. As previously said, it aids in the slow heating of the soil and water in the pipe, providing warmth to the plants.
The bubble wrap method, as previously described, can be used to protect outdoor plants located near the greenhouse’s wall. When the temperature drops, they help to keep vulnerable plants warm by insulating them.
Is this all too much for you? Composting for greenhouse heating is explained in this video.
Final Thoughts on How to Keep Your Backyard Greenhouse Heated
The ease and practicality of growing plants in a home greenhouse should persuade you to give greenhouse gardening a try. Now is the time to get your greenhouse and start reaping the rewards of growing your plants in one!