Cold frames are a great solution if you are looking to extend your growing season into late fall, winter, and even early spring. Cold frames act like a mini-greenhouse, to protect plants from frost, retain warmth, and allow you to harvest fresh vegetables well past the typical growing season.
What is a Cold Frame?
A cold frame is a transparent enclosure that traps heat from the sun to keep the soil warm and plants protected from the elements. It can be made from glass, polycarbonate panels, or heavy-duty plastic sheeting over hoops or wooden frames. By protecting plants from frost and extending the season, cold frames offer a head start in spring and a allow you to harvest beyond your first frost.
Why Use a Cold Frame?
Some people are perfectly happy growing summer vegetables. When fall comes around they are ready to put their garden to bed. Years ago that is what I did. Then I started growing a spring and summer garden. It wasn’t long before I was growing spring, summer and fall. I started using cold frames over simple PVC pipes one year when I still had a lot of spinach left in my garden and while it will withstand a frost, it won’t a freeze. I didn’t want all of that spinach to go to waste. I had spinach until February. Last year my collard greens were good until the end of December under that plastic. This year I have carrots , broccoli, collard greens and spinach that will be covered when it gets cold enough.
I placed rebar inside my beds then slipped the PVC pipe over. There are many different ways you can attach the PVC pipe. I suggest you visit your local hardware store and tell them what you want to do and have them show you clamps you can either use on the inside or outside of your bed. Generally these are in the plumbing or electrical aisle. My next PVC cold frame will have clamps on the outside of my bed. The rebar is impossible to remove in the spring. Lesson learned. I had my local hardware store cut my PVC pipe for me. I wanted my arched PVC pipe to be tall enough to accommodate my large broccoli plants. For a 4 foot wide bed you will need 8 foot of length of PVC pipe. This will create an arch that is 3 feet high. PVC pipe generally comes in ten to twelve feet lengths so if you can get someone to cut for you that would be great. Read on for my plastic recommendations.
NOTE: Place bricks, rocks, or pieces of wood along the bottom edge of the plastic sheeting to keep it anchored in windy conditions.
Choosing the Right Cold Frame Materials:
- Frames and Structures: You can make a cold frame from old window frames, wood, or PVC pipe, or purchase pre-made frames.
- Coverings: Use glass, polycarbonate, or greenhouse-grade plastic sheeting. Polycarbonate offers good insulation and durability, while glass provides clear visibility and can be recycled from old windows.
- Plastic Gauge: Look for heavy-duty plastic, typically around 4-6 mils (for single-season use) or 8-12 mils for extended durability.
- DIY or Pre-made: While DIY options are cost-effective and customizable, pre-made cold frames save time and often come with added features like ventilation controls.
NOTE: Cold frames made from wooden frames are harder to store. In the spring, I gather my PVC pipe and hang on a hook in my shed. I fold the plastic up and store it. Also, I’m a little concerned about glass breaking and then trying to replace.
Ventilation and Temperature Control: To prevent overheating, it’s essential to vent your cold frame on warm days. When temperatures rise above 50°F (10°C), open the frame slightly to allow fresh air in. If you use the PVC pipe like I do, just roll up the plastic on one side. To avoid cooking your plants, keep an eye out on the daily temperatures and adjust the ventilation as needed.
Watering Needs: Plants in cold frames may need more frequent watering due to increased warmth and limited airflow, so check the soil moisture regularly.
Cold frames aren’t just for the winter.
Seasonal Uses for Cold Frames:
- Spring: Use cold frames to harden off seedlings, transitioning them from indoors to the garden.
- Year-Round: Start cool-season crops early and protect tender plants during unpredictable weather.
Best Vegetables for Cold Frames: Vegetables that thrive in cool temperatures do well in cold frames, including:
- Leafy greens like spinach, lettuce, and arugula
- Root crops like carrots, radishes, and beets
- Herbs like parsley and cilantro
- Brassicas like cabbage and broccoli in early spring
Imagine turning your garden dreams into reality with a few easy steps. In this course, I’ll guide you through everything from choosing the best spot for your garden to harvesting your very first crop. Designed for busy beginners and small spaces, each module simplifies gardening so you can focus on enjoying the journey—and the harvest.
Enroll today, and let’s start growing!” I’m so excited about you growing your own food I am giving you a $2O discount. Just use the code GARDEN Don’t miss out another year of not growing your garden. Start growing TODAY
