How To Grow Plants Successfully In Greenhouse for Winter

Have you ever dreamt of plucking fresh tomatoes in the midst of a snowy December or relishing the crisp bite of lettuce in the frosty heart of February? It might sound like a gardening fairy tale, but this dream can be your winter reality with a suitable greenhouse for winter.

In this guide, we're diving deep into the secret sauce of growing organic vegetables even when the world outside is blanketed in snow. So, wear your gardening gloves, and let's unearth the magic of greenhouse in the winter together. Let's embark on growing vegetable garden journey together!

What are The Types of Winter Greenhouses

Traditional Greenhouse:

Its structure is strong, and its walls are glass or plastic. This type is perfect for cold season plant growth because of its insulation and temperature control. Glass or plastic walls trap heat, so ventilation avoids overheating. Traditional greenhouses have heaters and grow lights to promote and encourage plant growth even in cold months.

Lean-To Greenhouse:

A lean-to greenhouse attaches to a home or shed. Sharing a wall with the existing building it shares the heating system inside increasing the outside temperature and lowering construction costs. This style suits homeowners with limited space or those seeking an efficient solution to extend their gardening season.

Hoop House or Tunnel Greenhouse:

Tunnel greenhouses, or hoop houses, are inexpensive winter planting solutions. They are curved metal or PVC pipes wrapped in polyethylene. These easy-to-assemble shelters insulate plants from frost and chilly winds. Hoop houses extend the growing season for commercial growers and can be customized to suit different crops.

Cold Frame:

Winter plant protection is easy and inexpensive with cold frames. Small boxes with transparent tops are commonly made of glass or polycarbonate. Cold frames provide a microclimate to keep plants warm by capturing solar heat.

Portable Greenhouse:

Portable greenhouses, also known as pop-up or mini-greenhouses, are lightweight and easily movable protecting plants inside from the cold. These greenhouses are relatively affordable, easy to set up, and can be strategically positioned to maximize plant sunlight exposure and keep the heat inside.

How To Choose The Right Type Of Winter Greenhouse

Size and Space: The greenhouse should fit well within your available space, allowing for walking paths and ventilation.

Material: Look for sturdy frame materials like steel or aluminum and coverings like polyethylene, polycarbonate, or glass, each offering varying degrees of insulation.

Insulation: Double-walled or twin-wall coverings offer better insulation than single-walled structures, which is essential for retaining heat during winter.

Ventilation: Adequate vents, possibly automated, to regulate temperature air circulation and prevent overheating on sunny winter days.

Heating Options: Additional heating methods, like electric heaters or heat sinks, can benefit freezing temperatures and climates, keeping the greenhouse warm.

Foundation and Flooring: Consider whether it offers options for a solid foundation to prevent frost and flooring materials for drainage and weed control.

Durability and Weather Resistance: A robust structure that withstands heavy snowfall in the winter season, strong winter winds, and other extreme cold weather and conditions.

Modularity and Expandability: The flexibility to expand or modify the greenhouse in the future as your gardening needs evolve.

Shelving and Layout: Features like built-in shelving, plant hangers, and benching systems can optimize space and organization.

Ease of Assembly: Depending on your DIY abilities, consider whether the greenhouse can be easily assembled or requires professional installation.

Maintenance: Assess the level of upkeep required for both the frame and covering material.

Price: While not a physical feature, the cost is crucial in determining which greenhouse type fits within your budget without compromising essential features.

What Are the Easy-to-Grow Winter Greenhouse Plants?

Here's a list of winter crops that thrive in the cold nights and winter months:

Leafy Greens and Microgreens:

These winter greens are among the most popular winter vegetables that tolerate cooler temperatures.

• Winter Lettuce: Varieties like Winter Gem and Arctic King. These leafy greens are specifically bred for colder climates.

• Spinach: A cold-hardy crop, it can produce leaves all winter long if well-protected.

• Kale: Especially the winter varieties, can survive and produce leaves even in snowy conditions.

• Swiss Chard: Continues to produce flavorful leaves even in colder climates. Perfect for winter harvesting.

Root Vegetables:

With warmer soil than the air and cold temperatures, root crops can be an excellent choice for a winter greenhouse.

• Carrots: Varieties like Autumn King and Oxheart are suitable for winter.

• Beets grow well in more excellent conditions and can be harvested in winter.

• Radishes: Winter varieties, like Black Spanish and Watermelon, can be sown for winter harvest.

Brassicas: Many members of this family are cold-tolerant and perfect for winter gardening.

• Broccoli: Winter varieties can be grown for a late winter or early spring harvest.

• Cabbage: Especially winter varieties, can be planted for a late winter harvest.

• Brussels Sprouts taste even better after a light frost, making them perfect for winter gardening.

Herbs:

Many herbs can be grown in a winter greenhouse, providing fresh flavors for winter dishes.

• Parsley: This biennial herb can continue growing throughout the winter.

• Cilantro: Prefers cooler temperatures and can flourish in a winter greenhouse.

• Chives: They can keep growing in mild winter conditions.

Peas and Broad Beans:

Both can be sown in late winter for an early spring harvest. Varieties like Aquadulce Claudia broad beans are ideal for winter growing and overwintering.

Onions and Garlic:

Planting cloves in late autumn will result in an early summer harvest. Overwintering varieties are designed to cope with the colder conditions.

Asian Greens:

Bok choy, mizuna, and tatsoi are all cold-tolerant and can be grown successfully in a winter greenhouse.

These cold-hardy crops are ideal for extending your gardening season and enjoying fresh produce even when the weather turns chilly. It's important to consider your local climate and frost dates when planning your cold-season garden.

How to Grow Vegetables in a Winter Greenhouse

Choose the Right Greenhouse :

• Ensure that the greenhouse structure is appropriate for your local winter conditions.

• Look for a greenhouse with twin-wall polycarbonate panels, which provide better insulation than single-wall panels.

Plan for Heating :

• Invest in a greenhouse heater or automated heaters. Electric and gas heaters are the most common types.

• Calculate the BTU (British Thermal Units) needed based on the size of your greenhouse and your local winter temperatures.

• Monitor and maintain a consistent temperature. Use thermostats and max/min thermometers.

How to Boost Heat in an Unheated Greenhouse in Winter

One effective method in boosting an unheated winter greenhouse is insulation with bubble wrap or horticultural bubble wrap on the interior, which can provide added insulation, retaining warmth within the structure. Creating a thermal mass or heat sink is one of the simplest and least expensive ways to warm greenhouses in the cold.

Lighting:

• In many regions, winter means shorter days and less sunlight. Consider supplemental lighting, especially for plants that need a lot of light.

• LED grow lights are energy-efficient and provide a broad spectrum of light beneficial for plants.

• In case of a power outage, have backup heating methods available, like propane space heaters.

• Ensure there’s proper ventilation if using combustion heaters to prevent harmful gas buildup.

Ensure Proper Ventilation:

• Vents (roof and side) are crucial for regulating temperature and humidity.

• On sunny winter days, the greenhouse can quickly overheat, so having automatic vent openers can be beneficial.

Humidity and Insulation

• Monitor humidity levels. Too much humidity can lead to mold and diseases.

• Watering should be reduced in the winter since plants grow more slowly and there's less evaporation. However, ensure the plants remain adequately hydrated.

• Use bubble wrap or thermal screens to insulate the inside of the greenhouse. This traps heat and keeps the cold out.

• For added insulation and drainage, consider laying gravel or porous stones on the floor.

Soil & Plant Health:

• Use high-quality potting mix to ensure plants have proper nutrients.

• Rotate crops if you’re planting directly into greenhouse beds to prevent soil-borne diseases.

• Consider using raised beds or containers for better drainage and control over the soil.

Choose Suitable Plants and Plant at The Right Time:

• Some plants thrive better in cooler temperatures, such as lettuce, spinach, kale, and Swiss chard.

• If growing tropical or warm-season crops, ensure the greenhouse temperature never drops below their required minimum.

Regular Maintenance:

• Check for any structural damages, especially after storms. Repair holes, gaps, and tears promptly.

• Clean the greenhouse to prevent the buildup of diseases and pests.

• Make sure to water your plants, but do not overwater them.

• Greenhouses can harbor pests like aphids, spider mites, and whiteflies.

• Regularly inspect plants and use organic or chemical controls as necessary.

• Introduce beneficial insects, like ladybugs and parasitic wasps, to control pests naturally.

Common Problems of Greenhouse Gardening & Their Solutions

Overheating & Underheating:

Problem: Maintaining the correct temperature is crucial in a greenhouse. Overheating can occur on sunny days, even during the cold season, causing plants to wilt or get sunburned. Conversely, underheating can make plants susceptible to frost damage or hinder their growth. This can happen when temperatures drop.

Solution: To combat overheating, ensure proper shading using shade cloths and constantly open vents or doors when the temperature gets high to allow excess heat to escape. For underheating, consider investing in a greenhouse heater for cold winter months or use passive heating methods like storing water in large containers to release heat gradually.

Ventilation Issues:

Problem: Inadequate ventilation can lead to humidity buildup, creating an environment ripe for mold, mildew, and pests.

Solution: Regularly open vents and doors, especially during warmer periods. Automated vent openers can be beneficial as they react to air temperature changes. Also, consider installing exhaust fans to ensure a consistent flow of fresh air and to keep humidity levels in check.

Lighting Concerns:

Problem: Insufficient light can stunt plant growth and lead to leggy or weak plants. Especially young plants; during the shorter winter days, plants might need more light than they are getting naturally.

Solution: Augment natural sunlight with grow lights. LED or fluorescent lights designed for plants can provide the necessary light spectrum to support photosynthesis. Ensure they're positioned correctly and timed to mimic natural daylight hours.

Conclusion

There is something magical about entering a greenhouse where plants are warm and healthy. It's proof that humans can persevere in adversity and create environments where life can flourish. Remember that your expertise will increase as you gain experience with winter greenhouse gardening.

With knowledge, devotion, and a little love, gardening has no season. Let your greenhouse be the beacon of life and growth as the frosts set in and nature sleeps. Cheers to your winter gardening success and the many winter harvests that await!