Winter Greenhouse Guide: Tips to Keep Plants Thriving

The demand for green areas will rise over time due to its advantages for the environment and all living things. Now, growers do not only rely on natural weather conditions to flourish gardens and lush green lawns. They set up their indoor gardens in controlled conditions. Some popular methods for growing plants in artificial conditions include greenhouses, hydroponic systems, and grow tents.

Greenhouses provide plants with the right light, temperature, and moisture so they don’t have to deal with the outside weather. Plants grown in greenhouses are healthier, stronger, and less likely to get sick. However, they need extra care and maintenance in different seasons to adapt to the outside weather.

In winter, greenhouses require efficient heating mechanisms and proper insulation to keep the heat inside. With the right winter greenhouse tips, such as using insulating materials and introducing reliable artificial heating, growers can prevent plant damage and encourage healthy growth. 

Gardeners can find various indoor gardening systems at Growcycle, which offers guides on maintaining indoor green spaces. They can also purchase products such as heating systems, grow lights, and containers to improve their greenhouses.

What is Winter Greenhouse?

A winter greenhouse is a building designed to protect plants from cold weather during the winter months. It is specially built to maintain a warm environment inside, allowing plants to grow even when it's freezing outside.

Winter greenhouses use insulation and heating systems to keep the temperature stable and prevent plants from getting damaged by frost or cold temperatures. The controlled environment inside the greenhouse helps plants stay healthy and continue to grow, even in the colder season.

Winter Greenhouse vs. Summer Greenhouse

A winter greenhouse and a summer greenhouse both serve the same purpose of creating a controlled environment for plants, but they have different requirements due to the seasons they are used in.

Factors to Consider While Selecting a Greenhouse for Winter

When selecting a greenhouse for winter, it is important to consider factors that will help maintain a warm, stable environment for the plants despite the cold weather outside. Here are key things to think about:

1. Insulation

A greenhouse should have good insulation to keep the warmth inside and protect plants from the cold. Materials like double-glazed glass, polycarbonate, or thermal blankets are great at trapping heat. These materials help maintain a stable temperature and prevent frost from damaging the plants inside.

2. Heating System

Temperatures can drop dramatically during winter, so it’s essential to have a reliable heating system. This can include electric heaters, propane heaters, or even solar-powered heating systems. A good heating system will keep the greenhouse warm even when it's freezing outside, ensuring that plants stay healthy and continue growing.

3. Size and Space

Choosing the right size of greenhouse is important based on how many plants need to be grown. A larger greenhouse gives more space for plants but may also need more insulation and heating. It’s crucial to consider how much space the plants will need to grow properly and thrive.

4. Ventilation

Proper ventilation is still important during the winter months. Even though it’s cold outside, air must circulate inside the greenhouse to prevent too much humidity from building up, which could harm the plants. Greenhouses with adjustable roof vents or side vents are a good option, as they allow fresh air in while keeping the heat inside.

5. Material of the Structure

The greenhouse frame must be strong enough to handle harsh winter weather, such as snow and strong winds. Materials like steel, aluminum, or galvanized metal are ideal because they are durable and resistant to the elements. A sturdy frame will ensure the greenhouse stays standing and protects the plants from extreme weather.

6. Light Availability

In winter, sunlight is weaker, and daylight hours are shorter. Selecting a greenhouse that maximizes the amount of light inside is important. Materials like clear or translucent polycarbonate or glass allow more sunlight to come in. Growers may also need to add artificial grow lights to supplement the natural light and help plants grow.

7. Snow Load Capacity

If the area where the greenhouse is located gets heavy snow, it’s important to check the snow load capacity of the greenhouse. This refers to how much weight the structure can hold without collapsing. A greenhouse that can handle snow accumulation will prevent the roof from being damaged by snow or ice.

8. Flooring

The type of greenhouse flooring is important for drainage and maintaining the plants' health. Gravel, concrete, or brick floors are great choices because they allow water to drain properly, preventing puddles and moisture buildup. This can reduce the risk of mold or mildew, which can harm plants.

9. Weather Resistance

The greenhouse should be built to withstand tough winter weather, including freezing rain and strong winds. A well-built greenhouse with tightly sealed panels and a sturdy frame will protect plants from extreme conditions. The materials should also be weather-resistant to prevent damage during storms.

10. Energy Efficiency

An energy-efficient greenhouse helps reduce the cost of heating during the winter. Features like solar panels or thermal mass (materials that store and release heat) can help regulate the temperature inside without using too much energy. Choosing an energy-efficient greenhouse is good for both the environment and the wallet.

Ideal Plants to Grow in Greenhouse for Winters

Here are some ideal plants to grow in a winter greenhouse:

1. Leafy Greens

• Spinach: Spinach grows well in cooler temperatures, making it perfect for winter greenhouses. It thrives in the mild warmth of a greenhouse and can be harvested multiple times.
• Lettuce: Varieties like romaine, butterhead, and loose-leaf lettuce are ideal for winter growing. Lettuce prefers cooler conditions and will flourish inside a greenhouse with moderate temperatures.
• Kale: Kale is hardy and can grow throughout the winter. It tolerates low light and cold temperatures, making it well-suited for a greenhouse environment.
• Arugula: This leafy green grows quickly and loves cooler temperatures, making it an excellent choice for winter gardening.

2. Herbs

• Parsley: Parsley thrives in a greenhouse with consistent temperatures and light. It’s a hardy herb that can survive the winter months.
• Cilantro (Coriander): Cilantro can be grown indoors during winter. It prefers cooler temperatures and can be harvested in about 3–4 weeks.
• Thyme: Thyme is a hardy herb that does well in a greenhouse during the winter. It requires minimal attention and can grow through the cold months.
• Mint: Mint grows well in a greenhouse and can even spread quickly, so it’s best to keep it in containers.

3. Root Vegetables

• Carrots: Carrots, especially varieties suited for cooler temperatures, can grow in a winter greenhouse. They need well-drained soil and moderate sunlight.
• Radishes: Radishes grow quickly and do well in cooler conditions, making them an excellent option for a winter greenhouse.
• Beets: Beets tolerate cold weather and will thrive in a greenhouse that maintains a stable temperature. They need a bit more space for root growth.

4. Winter Flowers

• Pansies: Pansies can bloom during the winter months in a greenhouse, adding color to the indoor space. They are hardy and can tolerate cold temperatures.
• Cyclamen: Cyclamen are beautiful winter flowers that thrive in cooler temperatures and will bloom in a greenhouse through the winter.
• Primroses: Primroses can tolerate cold weather and are great for adding color to a greenhouse in winter.
• Violas: Similar to pansies, violas are hardy flowers that can bloom in the winter months inside a greenhouse.

5. Fruiting Plants

• Tomatoes: While tomatoes are generally warm-weather, certain varieties, like small cherry or bush tomatoes, can be grown in a winter greenhouse. They will require consistent warmth and light.
• Strawberries: Strawberries can be grown in a greenhouse during the winter, and some varieties are well-suited for year-round cultivation. They require a lot of light and moderate temperatures.

Heating System in Winter Greenhouse

A heating system is essential for maintaining the right temperature in a winter greenhouse. Here are some common heating options and considerations for a winter greenhouse:

• Electric Heaters

Electric heaters are one of the easiest ways to quickly regulate a greenhouse's inside temperature. However, growers must ensure all safety measures while using an electric heater. Keeping it on for long may cause gas leakage that could cause fire hazards. Also, growers may ensure the heat circulates well throughout the greenhouse via a suitable fan. 

• Radiant Heaters

Propane-powered radiant heaters can maintain the ideal temperature in the greenhouse. They use natural gas to heat the environment via IR radiation, which plants and interior surfaces absorb. The heater heats all areas equally, and there is no need for a fan to circulate the heat. 

• Unit Heaters

Unit heaters use electricity to heat the greenhouse and spread the heat throughout the area via a fan. These small heaters are convenient for regulating the inside temperature. Growers may attach it to the greenhouse’s roof. Additionally, connecting it via any opening to the exterior is preferable to get sufficient oxygen. 

• Hot Water

Hot water is another super-easy way to heat a greenhouse. Growers heat the boiler via biomass, allowing it to pass through several wall and surface pipes. While passing, hot water emits heat that efficiently and evenly warms the surroundings. It is a cost-friendly way of heating as growers can save on electricity costs.  

• Thermal Mass

It is good to increase the thermal mass of soil, clay, and water to regulate the necessary heat in the greenhouse. Also, keep these things preferably near the windows. These absorb the heat during the day and emit it during the night. In this way, growers may adjust the temperature without spending extra money. 

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How to Insulate a Greenhouse in Winters?

Insulating a greenhouse in winter is crucial for maintaining a stable, warm plant environment. Proper insulation helps retain heat, reduces energy costs, and protects plants from frost and extreme temperatures. Here are some effective ways to insulate a greenhouse during the winter months:

• Fix the Cracks

Any cracks or broken areas in the greenhouse materials impact its insulation and considerably waste heat. Moreover, cold air from outside is more likely to enter through them. For better insulation, growers should examine the greenhouse surfaces and fix cracks. 

• Add Insulation to the Walls

Growers may use reflective material for insulation to prevent heat loss from the walls. The area receives sunlight with this method, but the trapped heat can not escape the greenhouse. Usually, the wall facing north gets the least sunlight, and proper insulation is a must for growers. Adding leaves or gardening trash outside the north-facing wall is better for the extra insulation. 

• Insulate the Ground

The inside heat can leave the greenhouse via the floor. By adding reliable insulation, growers can save the required heat within the greenhouse. Polystyrene sheets can effectively hold the heat. Certain landscape fabrics maintain insulation by keeping the heat but can allow excess water to pass. These fabrics are suitable for maintaining water levels in a greenhouse. 

• Go for Bubble Wrap

Bubble wrap is an energy-efficient way of insulating greenhouse gases. It is super easy to introduce bubble wrap to insulate a greenhouse. Growers should measure the sides and ceiling of the greenhouse. Then, they should fix bubble wrap to the sides, frames, and roof of the greenhouse. Secure it tightly to the surfaces via nails, pins, or wires. 

• Mulch the Roots

Growers may add organic mulch to the plant roots to prevent the escape of proper heat. This organic matter acts as a barrier for retaining the heat inside. Plants do not have to suffer extreme frosts on colder nights with this mulch layer. Moreover, mulching the roots from winter frosts prevents root damage and positively impacts healthy plant growth. 

• Use Thermal Curtains

Thermal curtains are equally effective in regulating the greenhouse's temperature during summer and winter. On colder nights, they effectively hold the heat inside, preventing heat loss.

Aluminized or energy curtains are ideal as they keep the greenhouse warm in winter and cool during summer. The heat plants release is reflected into the greenhouse by these aluminized curtains. 

Winter Greenhouse Tips to Maintain Healthy Plants

Here are some tips for maintaining a healthy environment in a winter greenhouse:

• Growers should place the greenhouse in a spot that gets the most sunlight. For artificial lighting, they can use LED grow lights, which save energy while providing the right light for plants.
• Plants should be spaced properly to avoid overcrowding. Growers should know the ideal spacing for different seeds before planting them.
• Regular trimming is important to control overgrowth, as greenhouses have limited space. Too much plant growth can cause thinning and damage.
• Greenhouses are well-insulated in winter, so growers should use circulation fans to help warm air move evenly throughout the space.
• Vents can be opened when there is enough sunlight to improve ventilation.
• Watering should be done carefully in winter, as plants need less water. Growers can use a hygrometer to check soil moisture and water only when it is dry.
• High humidity in greenhouses can attract pests. Growers should regularly check plants and take action against pests if needed.
• It is important to keep the greenhouse clean by removing all plants and rinsing the surfaces with water. Dust and debris from the walls should also be cleaned.

Benefits of Well-maintained Greenhouse in Winters

In winter, a greenhouse creates the perfect environment for many types of plants. Here are some benefits that greenhouses offer during this season:

• Protecting Plants from the Cold: In harsh winter weather or during frost, plants can suffer serious damage and often die. A greenhouse keeps plants safe from the cold, providing a better climate for them to grow.
• Faster Harvest: By following the best winter greenhouse practices, growers can help plants, like vegetables and fruits, grow more quickly than those grown outside. Without the stress of extreme temperatures, nutrient shortages, or diseases, plants can mature and be ready for harvest in less time.
• Growing Many Types of Crops: A greenhouse allows growers to grow a wide variety of plants in one space. These controlled environments allow the growing of seasonal and off-season fruits and vegetables. With limited space, growers can produce many types of edible, ornamental, and other plants.
• Improved Air Quality for Plants: A well-maintained greenhouse offers plants better heating and insulation. Heaters and fans stabilize the temperature, creating a healthy and clean environment. Proper airflow and humidity levels help plants breathe easier, promoting their health.
• Stronger, Pest-Free Plants: Thanks to heating systems and humidity controls, growers can maintain the perfect moisture and temperature inside the greenhouse. This reduces the risk of pests and weeds entering. Regular monitoring also helps prevent these problems, ensuring healthier plants.

FAQs

Are Greenhouses suitable for winter?

Greenhouses are an excellent choice for growing plants in winter without damaging them. They provide plants with the necessary light for photosynthesis and the ideal temperature to promote growth despite unfavorable outside conditions. 

What is best to cover plants in winter?

Frost or extreme cold may damage the plants, so growers must cover them with a suitable covering. Frost cloths or burlaps are convenient for this. Growers can also use closures during intense winter. 

How do I reduce moisture in the Greenhouse?

To minimize moisture levels, growers may increase air flow, which can push away the excess water as vapors. A dehumidifier can also serve the purpose well. 

The Bottom Line

Winter greenhouses are good for growers who want to create healthy garden spaces, both indoors and outdoors. Growers should make sure to maintain a steady temperature and enough moisture inside these gardens. Growcycle for greenhouses provides many energy-saving heating and lighting options. Using these tools, growers can build strong and healthy vegetable and fruit gardens.

Sources

1. University of Minnesota - Deep Winter Greenhouses

2. University of Missouri - Turning Winter into Summer: How Greenhouses Work in the Winter

Disclaimer: This material is for informational purposes only and should not be relied on for legal, medical, financial, or any other form of professional advice.

About the Author

Victor Miller

Environmental Journalist Focused on Sustainable Agriculture

Victor Miller is an environmental journalist at Growcycle, where he covers the latest news, trends, and innovations in sustainable agriculture. He has a deep passion for storytelling that emphasizes ecological balance and responsible farming practices.

Before joining Growcycle, Victor worked for several agricultural and environmental publications, reporting on significant environmental issues and interviewing key figures in the sustainability sector. His work has been featured in various industry journals and online platforms.