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Coldframes

Cold frames give you the kind of growing control that a garden on its own cannot. Halls Greenhouses offers a range of aluminium cold frames with toughened glass, from compact low-profile models to the deeper Jumbo, suited to different plot sizes and growing habits. Whether you grow seedlings through to planting out, protect tender plants over winter, or want salad crops running later into autumn, there is a cold frame in the range to fit the job. All Halls Greenhouses structures carry a 12-year warranty.

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A cold frame is a low, glazed, unheated structure used to protect plants from frost, wind, and heavy rain while letting sunlight warm the soil and air inside.


Why Choose a Cold Frame?


A cold frame earns its place at several points in the gardening year, not just in spring.


The most common use is hardening off: the process of gradually acclimatising seedlings raised indoors or in a heated greenhouse to outdoor conditions before they go into the ground. Moving them into a cold frame first, with the lid propped open for increasing periods each day, gives them time to toughen up without the shock of full exposure.


Greenhouse types overview


Through autumn and into winter, a cold frame keeps salad crops such as lamb’s lettuce, corn salad, and winter purslane producing long after the open ground has given up. It also provides useful shelter for slightly tender plants that cannot take frost but do not need warmth. Alpines, overwintering salvias, and potted herbaceous perennials all sit well inside one.


In summer, the lid comes off or stays propped fully open, and the frame becomes a sheltered growing space for low crops directly in the soil beneath, or a useful overflow from a greenhouse that has run short of room.


Finding the Right Cold Frame for Your Garden


The practical question is whether you need a low, flat cold frame or something with more height.


The Standard Cold Frame is a compact, portable option suited to hardening off trays and pots, or sheltering small sowings of salad. It sits close to the ground, moves easily around the garden to follow the sun, and takes up minimal space on a patio or beside a greenhouse. A south-facing position against a wall will make the most of winter and early spring light.


Standard Cold Frame


The Jumbo Cold Frame offers considerably more depth. That extra internal height means more space for larger pots, taller plants at the seedling stage, and a more generous growing area if you want to sow directly into the soil beneath. Gardeners who produce a lot of seedlings in spring, or who want a cold frame that doubles as a productive growing space through summer, will find the additional room worthwhile.


Jumbo Cold Frame


Both models are aluminium-framed with toughened glass and can be repositioned as needed. If you also have a greenhouse, a cold frame placed nearby works well as a staging post between the two: seeds start inside, move to the cold frame for acclimatisation, then go out into the garden.


Greenhouse accessories


Cold Frames FAQs




Can I plant directly into the soil beneath a cold frame, or should I use pots?


Both work. Planting or sowing directly into the soil beneath eliminates the need to pot on and reduces transplant shock for crops like carrots, salad leaves, and early beetroot. Using pots and trays inside the frame gives you more flexibility to move plants in and out as conditions change, which suits the hardening-off process well.




What is a cold frame useful for beyond hardening off in spring?


Hardening off is one use among several. Through autumn, a cold frame extends the salad season considerably for cut-and-come-again crops and winter leaves. Over winter, it shelters plants that cannot tolerate frost or persistent wet but do not need active heat. In summer, with the lid removed or fully propped, it functions as a sheltered growing space for low crops or as extra capacity alongside a greenhouse.




Will a cold frame protect plants from a hard frost?


A cold frame is unheated, so it cannot guarantee frost-free conditions. It reduces exposure to cold, wind, and rain, and for many slightly tender plants that is enough through a mild winter. In a prolonged hard frost, additional insulation such as horticultural fleece laid directly over the plants inside will give extra protection. For plants that need frost-free conditions reliably maintained, a heated greenhouse is the appropriate choice.


Mini greenhouses




Do I need to ventilate a cold frame, and how often?


Yes, ventilation is important throughout the growing season. On sunny days, even in early spring, temperatures inside a closed cold frame can climb quickly enough to scorch seedlings. Propping the lid open, starting with a small gap and widening it as the day warms, prevents overheating and reduces the risk of fungal problems from stagnant air. Close the lid again before temperatures drop in the evening.




Ready to Find Your Perfect Cold Frame?


Browse the Halls Greenhouses cold frames range and pick the size that suits your plot. There is no need to do everything at once; a cold frame is a useful addition at any stage of the growing year.


Halls Greenhouses cold frames range