5 Essential Tips to Prepare Your Backyard Greenhouse for Cold Weather Cultivation

If you’re an avid gardener that wants to stay prolific when the days get colder and darker, you’re probably thinking about ways you can optimize your backyard greenhouse without breaking the bank. To help you in your journey, we have provided five essential strategies for preparing your greenhouse for those harsh winter months. 

Increasing your greenhouse insulation

Insulating your greenhouse should be your main focus if you want to maintain stable growing conditions without paying high heating costs. Upgrading your roof with more insulative glazing material, like triple layer polycarbonate over single pane glass or thin plastic sheets, is one way to do this. If replacing your glazing is too expensive for you this season, consider a more cost-effective solution like applying clear bubble wrap to the interior of your greenhouse glazing panels. Its air pockets provide excellent insulation and still allow light to penetrate.

Using foam board insulation on the north wall of your greenhouse is also a great way to insulate your growing space. The north wall of the greenhouse doesn’t get as much light in the winter and insulating it definitely helps to reduce heat loss. If you can find insulation panels with a reflective surface, these would be ideal for insulating your north wall, as the reflective surface will help to increase sunlight in the greenhouse. 

Selecting the right winter crops

Growing plants in a backyard greenhouse during the winter can be a rewarding endeavor, as certain plants thrive in the controlled environment that a greenhouse provides, even in colder weather. Some plants that typically tolerate the cold better include: leafy greens, herbs, root vegetables, brassicas (broccoli, cauliflower, cabbage), peas, onions, garlic, microgreens and cold-tolerant flowers (pansies, violas, primroses). 

winter_crop- greenhouse

When selecting plants for winter greenhouse cultivation, it’s important to consider your specific climate and the heating and lighting capabilities of your greenhouse. Some plants may require supplemental heating or lighting to thrive, especially in regions with very short days and extremely low temperatures during the winter months. If you can keep your greenhouse above a comfortable temperature at night (above 62°F) and you have supplemental lighting installed, it is entirely possible to grow warm-weather crops like tomatoes, bell peppers, flowers etc. 

To learn more about when to plant what to benefit from year-round harvesting, read our blog, Year-Round Greenhouse Planting Calendar

Heating Your Greenhouse Economically

Depending on your climate and what you’re growing in your greenhouse during the winter, your space might require an additional heating system (either to keep the greenhouse above freezing or support warm-weather plant growth).

One of the more energy-efficient ways to heat your backyard greenhouse is by using geothermal technology. A geothermal heating system uses the steady temperature of the earth under the greenhouse to maintain a comfortable temperature inside the greenhouse. Geothermal systems either circulate air or water through underground tubing to transfer heat to and from the greenhouse. While the initial installation can be costly, the operating costs are generally low.

wood stove in the greenhouse
Electric heaters are also a great option as they are straightforward and easy to install. For small greenhouses, a standard electric space heater with a built-in thermostat can be sufficient. They are best for areas with mild winters or for greenhouses that only need occasional heating. Propane or natural gas heaters can be more economical than electric heaters, especially for larger spaces. They require proper installation and ventilation for safety and optimal operation.

Heat pumps are also a very efficient way to heat a greenhouse, although their upfront cost is a bit more than the other options provided. Heat pumps transfer heat in and out of the greenhouse rather than create it by burning fuel, which is why they are considered highly efficient. Air-source heat pumps can be a viable option, especially in milder climates where they don’t have to work as hard to extract heat from the outside air.

To learn more about inexpensive ways to heat your backyard greenhouse, read our blog, 3 Ways to Heat Your Greenhouse for Free this Winter.

Optimizing your temperature and humidity control

Maintaining optimal temperature and humidity levels inside a greenhouse during winter is crucial for plant health and growth. One of the easiest ways to monitor the temperature and humidity levels inside your greenhouse is installing a thermostat. Programmable thermostats can be set to maintain different temperatures at different times of the day or night, according to the needs of the plants. 

For advanced setups, you can use an automated control system to monitor your environment with sensors and adjust the climate inside the greenhouse accordingly. With an automated controller you can manage the temperature, humidity, ventilation, shading and lighting (and more) in your greenhouse – giving you the most control of your environment.

sunsense_residential- greenhouse

Depending on your climate, you may need to either add moisture to the air with a humidifier or remove excess moisture with a dehumidifier. This is particularly important in climates where the indoor air becomes too dry when heated, or too humid due to plant transpiration and lack of ventilation. That being said, even in winter, proper ventilation is necessary to manage humidity and prevent the buildup of fungal diseases. Automated vent systems can be set to open when humidity reaches a certain level.

Pest and Disease Management

Maintaining a healthy environment in your backyard greenhouse during winter is important in order to prevent and control common pests and diseases. As a preventative measure, regularly inspect your plants for signs of pests and diseases. Early detection is crucial for effective control. Pay special attention to the undersides of leaves and the points where leaves join the stem. 

As mentioned above, you should implement good air circulation and ventilation to prevent the buildup of high humidity levels, which can encourage fungal growth. Open vents or use fans as needed, but be mindful of maintaining temperature. Also, avoid overcrowding your plants. Adequate spacing allows for better air circulation and reduces the risk of disease spread. Other preventative measures include regular cleaning of your tools and pots, proper spacing of plants, making sure you’re not over-watering, and quarantining new plants.

ladybug in the greenhouse

If you do find you have a pest problem in your greenhouse, introducing biological controls like beneficial insects (i.e. ladybugs or predatory mites) will help to ​control pest populations like aphids or spider mites. There are also natural pesticides you can use like neem oil, insecticidal soaps, and horticultural oils that are effective against many common pests and are safer for the greenhouse environment.

To learn more about managing pests in your greenhouse, check out our blog, 6 Common Greenhouse Pests and How to Manage Them.

Being able to grow year-round is highly rewarding but not for the faint of heart. Luckily, in this day and age there are many ways to connect with fellow greenhouse growers to get support and advice on your growing journey. At Ceres, we encourage building relationships and community engagement for personal ‘growth’. That’s why we created a Facebook group online for greenhouse enthusiasts, like you, to ask questions and provide answers to other growers. Be sure to check it out, and if you have any questions about Ceres specific residential greenhouses, contact us today.

Interested in winterizing tips for your commercial greenhouse? Visit our blog, 5 Strategies for Maximizing Your Commercial Greenhouse Efficiency in Winter.

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