COLD FRAME GARDENING

​December is an ideal time to plan a garden reset or makeover in preparation for the following spring and if not practising already why not try cold frame gardening.

Cold frame gardening is a method of planting different types of green life, mainly produce, in a microclimate created by a man-made structure.

The addition of a cold frame within the garden enables the growing season to be extended. They are versatile, require little surface area, ideal for a small garden and are easy to build, alternatively, they can be purchased flat pack or ready-made from an established retailer.

Essentially a cold frame is a bottomless box with a skylight, a halfway house between a greenhouse and exterior planting.
They can be positioned directly onto any garden bed and assist in warming bare soil in early spring.

The transparent lid allows the sunlight to enter and simultaneously prevents heat loss by convection which would otherwise normally occur, particularly during the night. Thus, a microclimate is generated with an increase in soil and air temperature and also providing protection against the elements, such as strong wind, rain, hail and even snow. Plants can be started earlier in spring, such as seedlings which can then be transplanted to open ground once established.

A variety of produce can be grown in a cold frame, the most popular being lettuce, spinach, kale and green onions. However, a variety of root vegetables and brassica can be grown too.

When deciding to position the cold frame, take in consideration that full sun is essential and the transparent cover should slope downwards at a slight angle facing southwards to absorb the heat from the sun and to allow for rain run off.

A cold frame can be constructed from any material, the sides being of a solid material such as wood or masonry and the top being of a transparent material such as glass. A wooden structure can look aesthetically pleasing as well as being portable too, whereas, brick or block structure will be a more permanent feature and choice of location should be greatly
considered before building.

The most simple method of construction being straw bales used as sides and an old disused glass window or door placed on top. Imagination is key!

It can be designed and built to suit your particular needs, hinges and handles attached for ease of opening the cover and if preferred one crop could occupy the entire cold frame or a combination of crops in rotation to provide produce throughout the year. It is important to ensure the transparent cover is clear from any debris, as this will inhibit heat absorption and with crops being under cover, regular watering will be required. Increased humidity can be a problem within a small enclosed area, therefore, allow for slight ventilation within the cold frame structure.

Specific frame designs are available so they can be positioned on a hard landscaped surface such as paving. These can take on the appearance of a miniature greenhouse and more suitable for potted plants.

Cold frames are cheap to buy, easy to build and easy to maintain. They can be sited directly onto a garden bed, gravel or a paved surface and are a valuable addition to any garden, large or small. A mobile and modular solution for growing plants, lower in price and occupying less space in comparison to a greenhouse, there are many advantages of
cold frame gardening.

​contribution from Oliver David Cook

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