Introducing a cold frame into your garden will extend the growing season and enable you to harvest more fresh produce over a longer period. No matter what climate you live in, cold frame gardening will provide a warmer growing environment and increase the varieties of plants that you can grow.
Read on to discover tips and tricks for using a cold frame in your garden.
What Is a Cold Frame?
A cold frame is basically a box with a transparent top. The see-through top allows the sun to penetrate through to the plants and soil, utilizing solar energy and the insulation of the soil to create a microclimate for the plants growing inside. It can be raised or slid open to release any excess heat that may damage the plants. Plants can either be grown directly in the underlying soil or raised in pots or other containers.
It’s called a ‘cold frame’ because it contains no man-made heating source and generates heat solely from solar energy. A cold frame is a perfect complement to a heated greenhouse to ensure healthy, productive plants.
A cold frame kit can be purchased or it can be a simple DIY project. With some leftover lumber and material to create a transparent top, such as an old window frame, you can build your own functional cold frame that will enable your garden to be more fruitful.
Choosing the Best Site for a Cold Frame
For maximum benefit, you need to carefully consider what will be the best location for your cold frame. To most effectively harness the warmth and light from the sun, the cold frame should be positioned to face south. It should also be sheltered from the prevailing wind. The easiest way to achieve this is to place the cold frame against the south facing wall of an existing structure, such as a house, a shed or a greenhouse. If this isn’t an option the north facing side of the frame can be protected and insulated by using straw bales.
Why Use Cold Frame Gardening?
Cold frame gardening allows plants to grow and produce food in the middle of winter. It’s an ideal way to grow and harvest fresh salad greens throughout the winter without using electricity.
Extending the garden season and growing salad greens is not the only things that using a cold frame will achieve. A cold frame makes a great addition to a heated greenhouse and performs several functions that a greenhouse cannot.
Support for Plants During Dormancy
Many plants need cold temperatures so that they go through their dormant stage and a cold frame will provide them with a protected place to overwinter. Temperatures remain above freezing but cool enough to promote dormancy in a cold frame, plus the transparent top allows you to view the plants without opening the top, and letting in the colder external air.
Darkness may also be required by some plants for dormancy and that is easy to accomplish with the aid of cardboard in the cold frame to block out the direct sunlight.
Certain perennial flowers also benefit from a cold frame. For instance, the beautiful Christmas cactus and poinsettia, both need a period of cool dormancy each year or they will not re-bloom.
Protection for Seed Starting
Utilizing a cold frame allows you to start seeds in a protected environment so that plants will be ready for transplanting very early in the season.
Garden seeds can be started in flat trays and placed on the ground inside the cold frame or the seeds can be sown directly into the soil underlying the cold frame. Either way will provide the seeds with the sunny shelter and constant temperatures they need to germinate.
Starting seeds in a cold frame also reduces the shock from transplanting the tender seedlings. They will be better acclimated and transplant shock will be reduced so, the seed success rate will improve.
Seeds of cool-season crops, like broccoli, kale, cabbage, and spinach, can be started in the cold frame earlier and be ready for transplanting sooner. This is ideal for climates with short growing seasons and will allow for two cool-season food crops each year – one in spring and the second one in the fall.
Gardeners in mild climates can sow seeds every two weeks in the cold frame so they can have plants ready for regular transplanting and enjoy a continual harvest of fresh food.
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Simplifies the Hardening Off Process
Plants started from seeds in a heated greenhouse will need to be hardened off before they are transplanted into an outdoor garden. Young seedlings must be gradually acclimatized to fluctuations in temperature, sunlight, moisture, and wind.
Without a cold frame, this hardening off process would entail manually carrying the plants outside, from the greenhouse, and back in again, every day, over the course of 7-14 days. The same effect can be achieved by opening and closing the transparent top of a cold frame. This makes the hardening off process so much easier.
Allows Growing Outside of the Frost Season
Gardening with a cold frame allows plants to continue to grow past the times of frost. Container-grown plants can be placed inside the frame to protect them and preserve the heat and sunlight inside whilst keeping the cold and frost at bay.
Any still viable plants being grown in-ground or in a raised bed can have a hoop house cold frame built over the plants. Cold frame construction over existing plants typically consists of PVC pipe or wire hoops with a plastic sheet covering. The components can be purchased separately or hoop house kits are available.
A removable cold frame, like a hoop house, also enables cool-season crops to be started earlier in spring.
Anything used to keep the cold and frost out and heat in will help make cold frame gardening a successful endeavor. It will extend the growing season so you can harvest and preserve more fresh fruit and vegetables from your home garden.
Cold frames are a garden tool that helps both home gardeners and commercial growers achieve a more successful growing season. Building or purchasing one will almost certainly be a worthwhile addition to your garden.