10:31 - 04 March 2011
A cold frame but its very nature means that it is not usually heated, so this does limit what you can grow in it early in the season to frost hardy plants. But that doesn’t mean it’s not useful. In fact few gardeners can manage without a cold frame or two in the garden.
In early spring the cold frame is a great place to nurture and bring on pots of flowering spring bulbs. You can hold back flowering by placing them out in the cold or bring on flowering by bringing them into a protected cold frame or greenhouse. If you have a particular need for flowers for special date or birthday, you can manipulate the flowering time quite significantly by moving the pots between cold frame and greenhouse.
The spring cold frame is ideal for growing early salads, hardy seeds and bringing on pots of cuttings. It is too cold to nurture tomatoes and tender plants but these can be brought on inside the greenhouse and moved into the cold frame in planters and growing bags as spring moves into summer. Many gardeners use tall coldframes to nurture summer tomatoes, freeing up valuable greenhouse space and protecting their plants from the risk of tomato blight.
By ventilating the cold frame on warm sunny days and closing it up in cold weather you can keep the internal temperature a little warmer than outside. It also protects the plants from cold and drying winds.
The spring cold frame is a great place to nurture hard wood cuttings taken last season. These can be repotted and grown on in the cooler cold frame environment. It is also a good place to nurture cuttings of other hardy plants such as perennials before planting them out into their final growing positions.
The spring cold frame is a good place for pots of hardy seeds such as sweet peas, broad beans, peas and more. As the temperature improves and spring starts to surface it can also be used to grow on half-hardy annuals before they are planted out into the garden.
The cold frame plays a vital role in the transition of plants from greenhouse to garden. This technique of hardening off is an essential process for many plants but especially bedding plants, vegetables and half-hardy annuals.
It’s important to limit hardening off to plants that can withstand a little cold, especially at night, so don’t try and harden off any plants that are tender, until the last risk of frost has passed. In the UK this is generally mid to late May, but depends where you are in the country, keep a close eye on the weather.
Use a cold frame to house a deep growing bag and raise an early crop of carrots, radish, lettuce or peas. You can replant the growing bag with something else when you have harvested the first crop.
You could also use a cold frame to bring on an earlier crop of potatoes. Plant some chitted first earlies into a deep growing bag within the cold frame and allow them to grow. Keep well protected from frost, you won’t get a huge crop, but it will make a lovely batch for a summer salad, Sunday lunch or picnic.
The spring cold frame is a good place to bring on a few pots of perennial herbs. Lift and divide a clump of chives, marjoram or parsley and pot into rich potting compost. Bring the pots into the coldframe and keep watered. These plants will grow an earlier crop of leaves than any outdoor plants and provide some welcome, early flavour.
