Cold frame gardening is an effective strategy for extending your growing season. whether you want Protect your plants from autumn frosts Or seedlings from spring cold snaps, these boxes are easy and inexpensive to make and simple to use.
Our guide to cold frame gardening will help you decide whether to try this technique to protect your plants when temperatures drop.
What is cold frame gardening?
Cold frame gardening involves placing a bottomless, below-ground box over tender plants or plants to protect them when temperatures drop. Frames come in a variety of materials, but the sloping top is always transparent to let light in.
It is common to use cold frames in late fall or early winter to extend the growing season of cool season crops by one month. They are also helpful in the spring, providing protection for early planted perennials from late frosts.
Some gardeners use cold frames to help hardening off seedlings Grown from seeds indoors, which requires gradual adaptation to outdoor conditions.
The temperature in the cold frame is typically about 5°F to 10°F higher than outside the box, which helps create a controlled microclimate. One side of the frame is usually higher than the other to capture as much sunlight as possible.
This slowly released solar energy warms the air inside the box, helping to prevent extreme temperature fluctuations (especially at night) and maintaining moist, warm soil.
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Types of Cold Frames
It is possible to build or purchase a cold frame. While DIY options are often wooden, you may want something more flexible so you can move it to different locations in your yard or fold it when you don’t need it.
Not sure whether to choose a portable, permanent or temporary cold frame? We’ve outlined the advantages and disadvantages of each below.
Permanent
Some cold frames are designed to be left in a suitable sunny spot on your patio all year round. Often, they are buried in the ground for better stability and insulation. Permanent cold frames are typically made from durable and aesthetically pleasing materials such as brick, cinder block, concrete or rot-resistant wood with treated, glass or plexiglass lids.
Temporary
If you’re experimenting with a cold frame or don’t want it to take up yard or shed space in the warmer months, a temporary cold frame may work if you don’t mind working for one season of use. Is.
Using old recycled materials, such as scrap wood, bricks, straw bales, old window glass, or plastic sheeting means you won’t waste money or materials if you have to get rid of the cold frame at the end of the season. . You can also use old milk jugs as cold frames for individual plants.
portable
Portable cold frames are lightweight and easy to fold or stack into your garden shed after the frost has passed. Garden supply retailers carry a wide range of collapsible frames (often made of aluminum).
However, portable frames are not as important as permanent designs. They do not always have such good insulation properties and are not as durable.
How to create a cold frame
Building a DIY Cold Frame Within reach of most convenient homeowners. Techniques vary depending on the material and design you choose. The steps below will help you understand if building a traditional wood cold frame is something you want to tackle.
- Use wooden deck boards (or other appropriately sized scrap wood) to create a 2-foot by 4-foot rectangular frame.
- Make the back edge of the frame higher than the front so the lid can slide down. 12 inches at the front and 18 inches at the rear is normal. Avoid anything taller than 3 feet; Otherwise, it may be difficult to reach inside.
- Insert an old glass window into a slotted wooden frame for the lid. You can drill plexiglass directly into wood.
- Attach the lid using door hinges to make it easy to open and close.
- Treat wood to make it weatherproof. Choose an exterior sealant or paint that is safe for use with food crops.
Best Crops for Cold Frames
Cold frames are great for hardening off gardening seedlings or protecting seeds sown outside in the spring from unexpected late frosts. You can also use them to enhance your vegetable garden harvest calendar. Below are some of the best crops for cold frames.
- Broccoli: You can plant these types of cool-season brassicas in a variety of climates and they can withstand light frost. Growing in cooler climates means you can plant them as late as September in some locations, with some broccoli varieties being ready to harvest in as little as 50 days.
- salad: Consider fast-growing, adaptable salad greens that mature quickly. Even when temperatures drop, you can still enjoy a healthy harvest within 40 to 60 days in cooler temperatures.
- Tomato: After germinating seeds indoors, harden off the tender seedlings in a cold frame. Same thing applies for chilli also.
Cold Frame Growing Tips
It’s not just the construction you need to get right when attempting cold-frame gardening. Keep the following tips in mind for the best chance of success.
- choose a sunny location: A site with southern exposure receives maximum heat from sunlight.
- provide shelter: Place the north end near a house, wall, fence or facing an insulation bale of hay to reduce exposure to cold wind.
- Well-drained soil is essential: A flooded cold frame is a recipe for disaster. Consider Adding amendments to aerated soil If your water is heavy and the water is not draining properly.
- Monitor temperature and ventilation: If the cold frame gets too hot on a sunny day, it can quickly destroy your plants. Consider attaching a thermometer and, when necessary, open the lid during the hottest part of the day to promote air circulation and cool temperatures.
