Protect Crops in the Greenhouse or Cold Frames in November: Tips and Advice for Winter Care

As temperatures drop in November, it’s important to take steps to protect crops growing in your greenhouse or cold frames. These structures are designed to extend the growing season by shielding plants from frost and cold weather, but they still need some extra care during the winter months. Proper insulation, ventilation, and maintenance will help ensure that your crops survive the winter and continue to thrive in the colder months. This guide will provide you with tips on how to protect your greenhouse or cold frame crops in November and keep them healthy through winter.

Why Protect Crops in the Greenhouse or Cold Frames in November?

While greenhouses and cold frames offer valuable protection against the elements, the colder months can still pose challenges, such as frost, condensation, and lack of light. By taking preventative measures in November, you can maintain optimal growing conditions and ensure your crops remain productive. Protecting crops now helps prevent frost damage, encourages continued growth, and prepares your plants for the harsh winter months ahead.

Step-by-Step Guide to Protecting Crops in the Greenhouse or Cold Frames in November

1. Check and Repair the Structure: Before winter sets in, inspect your greenhouse or cold frames for any cracks, gaps, or damage that could allow cold air or moisture to enter. Check doors, windows, and ventilation flaps for proper sealing. Repair any broken panels, replace damaged glass or plastic, and ensure that the structure is airtight. In cold frames, ensure that the lids are securely fastened and that no drafts are entering.
2. Insulate for Cold Weather:

• Greenhouses: In a greenhouse, adding insulation can help maintain a more stable temperature. Bubble wrap is a popular choice for insulating greenhouse walls and roofs. Secure bubble wrap to the inside of the structure to add an extra layer of protection against the cold while still allowing light to pass through.
• Cold Frames: For cold frames, adding an insulating material like straw or leaves around the outside can help protect plants from freezing temperatures. You can also use old blankets, frost cloths, or garden fleece to cover the cold frame during particularly cold nights.

1. Use Heaters or Heat Mats: If your region experiences extremely cold temperatures, you may want to add supplemental heating to your greenhouse or cold frames. Electric heaters or propane heaters can be used in greenhouses, but be sure they are safe and properly ventilated. For smaller spaces or delicate seedlings, heat mats placed under trays can help keep the root zone warm without overheating the entire structure.
2. Monitor Ventilation: Proper ventilation is crucial, even during the winter months, to prevent condensation and fungal diseases. In greenhouses, open vents or windows on warmer days to allow fresh air in and reduce humidity. For cold frames, prop the lid open slightly on sunny days to increase airflow. However, be sure to close the vents at night or when temperatures drop to prevent cold drafts from damaging your crops.
3. Water Sparingly: During the winter months, plants in greenhouses and cold frames generally need less water, as growth slows and evaporation decreases. Be mindful of watering schedules and avoid overwatering, as excess moisture can lead to root rot or fungal diseases. Water your crops in the morning to allow any excess moisture to evaporate during the day.
4. Add Mulch for Extra Protection: In both greenhouses and cold frames, adding mulch around the base of your plants can help insulate the soil and retain moisture. Organic mulch, such as straw, shredded leaves, or compost, helps protect plant roots from freezing temperatures. Mulching is especially helpful for overwintering crops like spinach, kale, or lettuce.
5. Provide Supplemental Lighting: Winter days are shorter, and some crops may require additional light to continue growing. In greenhouses, consider adding supplemental lighting, such as LED grow lights, to extend daylight hours and encourage continued growth. Cold frames generally rely on natural light, so position them in a sunny spot if possible, but supplemental lighting can be added to cold frames in areas with limited winter sunlight.

Crops That Benefit from Greenhouse or Cold Frame Protection

• Leafy Greens: Spinach, lettuce, kale, and Swiss chard grow well in greenhouses or cold frames during the winter months. Protecting these crops from frost ensures a continuous harvest through the cold season.
• Herbs: Herbs like parsley, cilantro, and chives can thrive in protected environments through the winter. Keeping them in a greenhouse or cold frame helps extend their growing season.
• Root Vegetables: Carrots, radishes, and beets can be grown in cold frames or greenhouses, especially when they are insulated and protected from frost.
• Brassicas: Hardy crops like cabbage, broccoli, and Brussels sprouts benefit from the controlled conditions of a greenhouse or cold frame, as they can continue to grow in cold weather.

Benefits of Protecting Crops in Greenhouses or Cold Frames

• Extends Growing Season: By protecting crops in greenhouses or cold frames, you can extend your growing season well into the winter months, providing fresh produce when outdoor growing is no longer possible.
• Prevents Frost Damage: These structures protect crops from frost, which can severely damage or kill plants. Adding insulation or supplemental heat ensures that crops remain protected even during cold spells.
• Improves Air Circulation and Reduces Disease: Proper ventilation prevents condensation and reduces the risk of fungal diseases in greenhouses and cold frames. Winter protection allows plants to grow in a controlled, disease-resistant environment.
• Maintains Optimal Growing Conditions: With the right care, greenhouses and cold frames provide a stable environment for crops, helping to regulate temperature, moisture, and light levels. This allows for more consistent growth throughout the winter.

Additional Tips for Protecting Crops in Greenhouses or Cold Frames in November

• Use Frost Cloths for Extra Protection: On particularly cold nights, drape frost cloths or blankets over your crops inside the greenhouse or cold frame. This adds an extra layer of insulation and helps prevent frost damage.
• Check for Pests: Although greenhouses and cold frames provide protection, they can still harbor pests like aphids or slugs. Regularly inspect your crops for any signs of pest activity and take appropriate measures to control infestations.
• Rotate Crops: Just like in outdoor gardening, practicing crop rotation in greenhouses or cold frames helps prevent soil depletion and reduces the risk of disease. Plan to rotate your crops seasonally to maintain soil health.
• Keep the Greenhouse or Cold Frame Clean: Clear out any dead leaves, plant debris, or old containers to keep your greenhouse or cold frame tidy and disease-free. A clean environment promotes better air circulation and reduces the likelihood of pests or diseases taking hold.

Common Questions and Answers

Q1: How often should I water crops in my greenhouse during winter?
Water sparingly in winter, as plants require less water due to slower growth and lower evaporation rates. Water when the top inch of soil feels dry, and avoid watering late in the day to reduce the risk of cold, wet soil overnight.

Q2: How can I keep my cold frame warm in freezing temperatures?
To keep your cold frame warm, use insulating materials like straw or leaves around the base, add a frost cloth or blanket over the top at night, and ensure the frame is tightly sealed. If necessary, consider using a small heat source, such as heat mats, to keep the root zone warm.

Q3: Can I grow crops year-round in a greenhouse?
Yes, with the proper care, including supplemental lighting and heating, you can grow many crops year-round in a greenhouse. Crops like leafy greens, herbs, and even some fruits can thrive in a well-maintained greenhouse during winter.

Q4: How do I prevent condensation and fungal diseases in my greenhouse?
Ventilate your greenhouse regularly, especially on warmer days, to reduce humidity and condensation. Use fans or open vents to circulate air, and avoid overwatering, which can contribute to excessive moisture and fungal growth.

Q5: Can I grow tender crops like tomatoes or peppers in a cold frame during winter?
Cold frames are not typically warm enough for tender crops like tomatoes or peppers during winter. However, these crops can be grown in a heated greenhouse if you maintain the necessary temperature and light conditions.