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Winter Greenhouse Gardening: What to Grow & How to Care for Plants

Winter is often thought of as a time when gardening takes a backseat, but for those with a greenhouse, the growing season never truly ends. With the right preparation and care, your greenhouse can thrive year-round. Here, we'll explore what to grow during the winter months and how to care for your plants to ensure a productive and healthy greenhouse.

What to Grow in a Winter Greenhouse

Winter greenhouse gardening focuses on cool-season crops and plants that can thrive in lower light and cooler temperatures. Here are some of the best options.

Leafy Greens

  • Lettuce: Varieties like romaine, butterhead, and leaf lettuce grow quickly and tolerate cool conditions.
  • Spinach: Thrives in cooler temperatures and provides a continuous harvest.
  • Kale: A favorite here at BC Greenhouse Builders. Hardy and nutrient-dense, kale is a winter greenhouse staple.

Root Vegetables

  • Carrots: Short and early-maturing varieties perform best in winter.
  • Radishes: One of the fastest-growing root vegetables, perfect for quick harvests.
  • Beets: Ideal for moth their roots and greens.

Herbs

  • Parsleycilantro, and chives are hardy herbs that grow well in cooler conditions.
  • Thyme  and oregano can also thrive with adequate light.

Cold-Hardy Vegetables

Microgreens

  • These nutrient-packed greens grow quickly and are perfect for small spaces.

Small lemon trees are overwintered in my smaller cool greenhouse.

How to Care for Winter Greenhouse Plants

Caring for plants during the winter months requires attention to detail and adaptation to seasonal challenges. While growing conditions may differ from other times of the year, a few fundamental practices can ensure your plants stay healthy and productive.

Maintain Optimal Temperatures

One of the most important aspects of winter greenhouse care is maintaining optimal temperatures. Many winter crops thrive in temperatures ranging from 45°F (7°C) to 65°F (18°C). This balance can be achieved using a reliable greenhouse heater to provide warmth during cold nights and proper ventilation to avoid overheating on sunny days. A thermometer placed in your greenhouse is essential for monitoring these fluctuations and ensuring your plants remain within their preferred range.

Palma Twin Greenhouse Heater image

Palma Twin Greenhouse Heater

$199.99

Durable and efficient 1500W greenhouse heater with 5120 BTU heat output, splash-proof design, and a fan-only mode for versatile use in spaces up to 120 sq. ft.

Maximize Light

Lighting is another critical factor for winter greenhouse success. Since days are shorter and sunlight is weaker during the winter, plants may not receive adequate natural light. Placing crops where they can capture the most sunlight is a good start, but supplemental grow lights can make a big difference. These lights can extend the growing hours to 12-16 hours per day, providing your plants with the energy they need for healthy growth.

Water Wisely

Watering practices also need adjustments in winter. Plants generally require less water during colder months due to slower growth rates and reduced evaporation. It's best to water in the morning, allowing any excess moisture to evaporate during the day. This approach minimizes the risk of root rot and fungal diseases, which are more likely to occur in damp conditions. Good drainage is equally crucial; ensuring your pots and soil allow excess water to escape.

Control Humidity

Humidity levels inside the greenhouse should also be carefully managed. High humidity can create an environment where mold and mildew thrive. A simple way to regulate this is having a greenhouse/outdoor-use fan running around the clock in your greenhouse garden. This will allow for increased airflow causing moisture to circulate either out your vents or to your plants to help in their growth. Ventilation and spacing plants appropriately improve air circulation and reduces the risk of fungal issues.

Air King 6-Inch Clip-on Fan image

Air King 6-Inch Clip-on Fan

$43.99

The perfect durable clip-on fan for greenhouse use, providing powerful airflow and easy installation. Adjustable and compact, ideal for tight space.

 

Soil and Fertilizer

The soil and nutrients you provide also play a key role in winter plant care. Using nutrient-rick, well-draining soil sets your plants up for success. While plants grow more slowly in winter, they still require consistent supply of nutrients, albeit in smaller quantities. Over-fertilizing can stress plants, so use fertilizer sparingly and according to the needs of each crop.

Pest Management

Pests, although less prevalent in winter, can still pose a threat to your greenhouse garden. Regularly inspect your plants for signs of common greenhouse pests like aphids or whiteflies. Organic methods, such as neem oil or insecticidal soaps, can help manage these pests without harming your plants.

By taking these steps, your winter greenhouse will be well-equipped to produce a bounty of fresh and healthy plants all season long.

Additional Tips for Success

  • Plan Ahead: Preparing for winter gardening begins in late fall. Start seeds early to ensure they're established before the coldest months. Choose crop varieties specifically bred for cold hardiness to maximize your chances of success.
  • Use Insulation: Insulating your greenhouse can significantly reduce heating costs and maintain stable temperatures. Consider lining the interior with bubble wrap or thermal blankets to trap heat. Pay special attention to door and vent deals to prevent drafts.
  • Rotate Crops: Crop rotation is vital for maintaining healthy soil. Avoid planting the same crops in the same location year after year, as this can deplete nutrients and encourage soil-borne diseases. Plan your layout carefully to ensure diversity.
  • Keep It Clean: A tidy greenhouse is a healthy greenhouse. Regularly remove dead leaves, weeds, and plant debris to prevent pests and diseases from taking hold. Disinfect tools and pots between uses to minimize the spread of pathogens.
  • Monitor Regularly: Regular checks are crucial for catching problems early. Look for signs of pests, nutrient deficiencies, or temperature fluctuations. Addressing issues promptly will save you time and resources in the long run.
  • Leverage Companion Planting: Pairing compatible plants can deter pests and promote healthy growth. For instance, planting marigolds near your vegetables can help repel harmful insects.
  • Invest in Automation: Consider adding automated systems for temperature, lighting, and watering. These tools can help maintain consistent conditions and reduce the time spent on manual adjustments.

Cape Cod Display Sweden 10x18 SG6 Early Winter 3

Winter greenhouse gardening offers a rewarding way to enjoy fresh, homegrown product even in the coldest months. By choosing the right crops and providing proper care, you can keep your green thumb active year-round. Whether you're a seasoned gardener or just starting out winter, is the perfect time to embrace the magic of greenhouse gardening. Happy growing!

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