What are cold frames?
Put simply, a cold frame (sometimes called a cold frame greenhouse) is a bottomless box that is placed directly onto the soil or a raised bed.
The glass roofs of cold frames should be angled towards the sun in order to capture as much light as possible. Typically, the temperature inside a garden cold frame is between 5 and 10 degrees warmer than the outside environment.
This difference in temperature means gardeners can extend the growing season by a few valuable weeks, while protecting plants and seedlings from high winds, heavy rainfall, snow and freezing conditions.
If you’re a keen vegetable gardener, placing a cold frame directly onto your veg patch warms up the soil to enable early planting, at the same time providing protection from wind, rain and bugs.
Benefits of our Cold Frames
Discover the unique features of our cold frames, which distinguish them from other cold frames for sale.
- Easy access – with a sliding roof and side panels, gaining access to our cold frames is extremely easy. For even more accessibility, the panels can even be lifted out completely.
- Superior ventilation – sliding panels also mean better ventilation. On cooler days, opening a panel slightly can help prevent diseases associated with moist or stagnant air, while in the summer heat the panels can be wide open.
- Windproof – as our cold frames are fully glazed using toughened safety glass, their substantial weight will prevent them from blowing away, even in storm force winds. Their strong aluminium framework also comes with a 25 year guarantee.
- Moveable frame – although the glass makes our cold frames heavy, once the panels have been removed, the aluminium framework can be lifted easily. This allows the earth to be dug over or the cold frames to be moved from place to place.
- Quality glass – while plastic scratches easily, attracts dirt, degrades in sunlight and can bow in the wind, our glass panels are strong and rigid. They’re also easy to clean with excellent light transmission, reflecting heat radiated from within back into the cold frame.
- Removable roof panels – the top panels on our cold frames can be removed in late spring to allow taller plants to grow out through the roof and rain to enter. With the side panels still in place, the soil remains warm and plants are protected from the wind.
The best spot for cold frames
As cold frames are passive solar collectors, and are designed to capture heat, the best place to position them is usually somewhere that offers full sunshine, but also some shelter.
In the UK and the rest of the northern hemisphere, that means the sloping top is best positioned to face south, southeast, or southwest. This allows the maximum amount of sunlight to enter the sunlight into the cold frame greenhouse during winter, when the sun travels lower in the sky.
If you’re sowing or planting directly into the ground, it will obviously be put on top of your chosen bit of soil. However, if you use your cold frames mostly for growing cuttings, it would be better to put them somewhere shady.
Cold frame accessories and spares
We’ve a wide range of cold frame accessories you could add to your cold frames, including shade covers to reduce the amount of light entering the cold frame and louvre vents to increase the level of ventilation in your garden cold frame.
We’ve also seed tray shelves and shelf covers in a variety of sizes, plus mist watering equipment and heaters. And, to reduce the amount of bending you have to do when gardening, we’ve a sustainably-sourced, three-tier timber base to raise the height of our cold frames.
As for cold frame spares, there are channel liners, handles for roof and side panels and replacement glass. Although for peace of mind, you could take out our two-year accidental glass breakage cover.
All our cold frames can be colour coated in a choice of seven attractive shades.
What can I grow in a cold frame?
Can you start seeds in a cold frame?
Cold frames are the ideal place to sow early spring seeds, either directly into the soil beneath your garden cold frame or in seed trays.
How tall should a cold frame be?
Ideally, the height of your cold frame greenhouse should be slightly taller than the height of the plants you’re growing inside when they reach maturity.
The great thing about our cold frames is that the glass roof sections can be removed to allow taller plants to grow out through the top.
How do you keep a cold frame warm at night?
In general, cold frames require little or no protection at night. However, if snow or frost are forecast, you could place a layer of bubble wrap or newspaper inside your cold frame.
Alternatively, you can cover your plants with a layer of horticultural fleece, which will help retain heat from the soil. Or you can fill three or four large plastic drinks bottles with very hot water and place them in the cold frame, then cover the frame with a heavy blanket.
Why use a cold frame?
Cold frames are an ideal environment in which to raise cuttings, sow seeds and protect young or tender plants before they are planted in a garden. They are also a practical alternative to greenhouses if you lack the space.
Do cold frames protect plants from frost?
Garden cold frames will protect young plants and cuttings from the first frosts of autumn, but not the severe frosts later in the year.
From mid autumn and through winter, a layer of bubble wrap can be placed inside cold frames to provide some insulation against frosts. But remember that this will reduce the amount of light and ventilation getting into the cold frame.
Does a cold frame need to be in the sun?
The whole idea behind cold frames is that they offer ideal growing conditions by capturing the heat of the sun. So yes, cold frames should be placed where they have maximum exposure to sunlight.
In the UK, this means placing the sloping top of your garden cold frame so that it faces south. If this is not possible, southeast, or southwest or good alternative positions.
What’s the difference between a cold frame and a greenhouse?
The main difference between a cold frame and a greenhouse is that cold frames are not heated, relying instead on heat from the sun. Of course, with most standing just a few feet tall, cold frames are much smaller than greenhouses.
However, just like a greenhouse, cold frames can be ventilated. This can be done by sliding open the top or sides panels, or fitting an automatic louvre system to your garden cold frame.
What direction should a cold frame face?
The ideal spot for a cold frame is in a position where its sloping top is facing south. This is because cold frames work by capturing the heat of the sun, and south-facing is where it will get the most sunlight during the day. If this is not possible, cold frames should be located with the top facing southeast or southwest.
How can we help?
How can we help?
We hope you’re now aware of the many benefits of our aluminium cold frames, particularly as an ideal accessory to your greenhouse.
If you have any questions or need some further gardening advice about our cold frames, please contact us by calling 01788 822 301 or emailing [email protected].