A greenhouse is a great way to grow produce in the summer that would not normally grow in your climate zone. But, how can you use it in the winter to maintain your produce growth?
Using a greenhouse in the summer is easy but in the winter months when the weather gets cold it can be challenging to keep produce growth consistent. To use your greenhouse effectively in the winter and keep producing healthy harvests there are a few key steps you can take, such as installing insulation and ensuring the temperature remains constant. There are free methods for doing this as well as more high-tech approaches. Let’s take a look at both these ways for preparing your greenhouse and then see how best to use it in the winter.
- Avoid The Freeze
- It’s All About Temperature
- How to Heat a Greenhouse in Winter For Free
- What to Grow in Greenhouse in Winter
Avoid The Freeze
If you are feeling the weather turn towards the colder side then you can bet the plants in your greenhouse are feeling it too. It’s time to jack-up the heat.
A key to successfully using your greenhouse in winter really comes down to how well it is heated and how well it retains that heat.
Ensuring that you greenhouse has sufficient heating will protect your tender plants from being harmed and even killed by frost while also ensuring you continue getting a harvest even out of season.
A properly prepared and maintained greenhouse is a great way to keep your plants warm and content until spring comes.
What’s more heating your greenhouse will open up to you an entirely new world of gardening in the winter.
Heating the Greenhouse
Unfortunately, heating a greenhouse using purely modern electrical equipment can be very expensive in purchase costs and in electrical bills, especially if you have a large structure and a lot of plants to protect.
Luckily, there are ways to greatly minimize the cost and in some cases eliminate it entirely.
Ways to Heat the Greenhouse
If you have the budget then by far the best way to heat your greenhouse is with modern electrical equipment. These devices have been designed specifically to spread even heat throughout the greenhouse to keep temperatures constant.
If you can afford to get such a heating system then I highly advise you to do it, especially if you have a large greenhouse and plants that mean a lot to you.
However, not everyone has the budget to invest in modern equipment and for small greenhouse owners the cost may seem too extravagant for what is, essentially, just a hobby.
So here I have included the most modern ways for heating your greenhouse as well as ways to do it for free.
For most readers a hybrid approach will be more than enough to fully winter-proof your greenhouse.
It’s All About Temperature
The key to winterizing your greenhouse lies in regulating the temperature.
As the weather turns colder it becomes harder for your greenhouse to retain its natural heat.
Less sunlight and plummeting temperatures means those plants that were giving you the great harvests you were getting in the summer can fast turn into frozen slushy messes.
The only way to avoid this is to ensure the temperature in your greenhouse doesn’t match the temperature outside it.
Use a Thermometer
Regardless of whether you want to use expensive methods for preparing your greenhouse for winter or if you intend to use only free methods you must invest in a thermometer!
You cannot regulate the temperature in your greenhouse if you don’t know what the temperature is.
A good thermometer and humidity monitor (more on humidity later) is very cheap but essential for winterizing your greenhouse.
A thermometer and humidity monitor helps you ensure the environment in your greenhouse remains consistent.
If the temperature drops too low you can act quickly to fix this before disaster strikes and as the temperature starts to rise when winter begins to come to an end you can take steps to reduce your heating efforts.
Consider Investing in a Greenhouse Heating System
It’s the 21st century and we have some amazing horticulture gadgets at our disposal.
If you have the budget I highly recommend you invest in a greenhouse heating system.
Though these systems tend to be expensive good ones can ensure you keep your plants healthy and anyone who gets one believes they were worth every penny when they are still protecting their plants many years after initial purchase.
As with any type of product there are higher-end heating systems and budget ones. Chose a greenhouse heating system that best fits your needs.
If you are going to use a greenhouse heating system then I strongly advise you to get a thermostat. Most of the more expensive heating systems will have their own built-in thermostat but you can buy them separately.
There are a variety of really good thermostats that range in price from a couple of hundred bucks to those that cost less than the price of a lunch.
Position Heaters Carefully
If you choose to use a heating system and have a large greenhouse that requires multiple heaters be careful how you place them. This applies to the positioning of just one solitary heater as well.
If you are using an electric fan type of heater then these units are best sited in an open and central point at one end of the greenhouse.
Don’t point a heater directly at your plants. Instead angle it so the airflow is directed above plants that are close to it.
This is essential for the prevention of foliage damage.
Please do not position a heater close to a water source or where it may come into contact with water. I know this is common sense but the amount of accidents that occur yearly due to the poor positioning of heaters is alarmingly high.
If Cost is a Concern – Heat Sparingly
If you have to heat a very large greenhouse using modern equipment costs can spiral quickly. This can lead to unnecessary cost if, for example, you only have a few delicate plants that need protecting in the winter.
There are hardy plants that can survive in your greenhouse with minimum heating while there are others that need nurtured.
Group the more delicate plants together and erect some type of solid perspex partition or use curtains of bubble wrap insulation (more on that later) to divide the greenhouse up into small manageable zones that you can heat individually and thus more economically.
Investing in a heated propagator or a heat mat for seeds will greatly help your germination rate in the winter.
If you don’t buy anything else then at least get a few heat mats for those plants and seeds that are prone to the “winter blues”.
For most seeds a simple windowsill propagator will offer enough protection.
How to Heat a Greenhouse in Winter For Free
For some hobbyists the cost of modern greenhouse heating equipment cannot be justified. Likewise, if you have just a small greenhouse then you may not want to spend a lot of money on electrical heaters.
So, for the more budget-conscious among us here here are some ways to heat your greenhouse in winter for free.
There are specific materials you can use for greenhouse insulation but a great cheap alternative is to use bubble wrap.
Although not as effective as commercial grade reflective foil insulation you can easily and affordably insulate your greenhouse through the use of cheap bubble wrap.
Clipping a layer of bubble wrap to the the inside of your greenhouse frame will greatly reduce heat loss while simultaneously reducing the effect of cold winter winds.
Even if you do not intend to heat your greenhouse it will greatly benefit from bubble wrap insulation.
You can buy specially made horticultural bubble wrap insulation from most garden centers and although this is toughened to withstand extra abuse and is also UV stabilized standard bubble wrap usually does just as good a job.
Bubble wrap with larger bubbles will let in more light so try to avoid the small bubble type.
How to Bubble Wrap a Greenhouse (video)
Use a Garden Fleece
A horticultural garden fleece is a very inexpensive way to protect your plants in the coldest days of winter.
Even if you are using a heating system in your greenhouse using a horticultural fleece will provide a few more degrees of heat and protection to your plants on very cold nights.
You should only use a fleece at night as it blocks the light from getting to your plants and if left on for long periods will greatly affect ventilation (if your plants haven’t died from light deprivation first).
Many times new gardeners are so concerned about heating their greenhouses in the winter that they totally forget about ventilation.
Locking your greenhouse up against the cold like a winter Fort Knox is great for protecting your plants against the cold but they also need good air circulation.
The biggest problem for many gardeners when it comes to winter greenhouse warming is not actually regulating the temperature but is dealing with the increased humidity.
If you want to prevent fungal infections and other horticultural diseases from spreading throughout your greenhouse then proper ventilation is essential.
One way to help keep humidity levels low is to water your plants sparingly and in the mornings.
When the weather is mild you should attempt to clear any condensation by opening vents. In fact, you should do this on warmer sunny mornings even if there is no condensation.
Leave vents open for a few hours or longer if it is a very mild or warm day but definitely ensure that they are closed before the sun goes down and the temperature drops significantly.
What to Grow in Greenhouse in Winter
Now that you know how to prepare and how to use a greenhouse in the winter let’s look at what you can grow in it during those colder months.
Many vegetables that are easy to grow at home in pots are ideal candidates for winter greenhouse growing.
Vegetables to Grow in Winter
Below are a few vegetables that grow really well in the winter in a properly prepared and maintained greenhouse.
Of course this is only a short list and there are many other things that you can grow in your greenhouse in the winter and I recommend you do a little research into it.
- Broad Beans
- Brussel Sprouts
- Chinese Parsley
- Mustard Greens
- Pak Choi
- Spring Onions
- Winter Cabbage
- Winter Salads