The Starter’s Guide to Using Cold Frame in Gardening

What is cold frame gardening

Cold frame gardening is a form of planting different types of green life in an enclosed environment with the aim of extending the growing season of the plants. Building a cold frame is not a hard task. All you need is to make a wooden panel frame from an old glass window and put the glass over the frame. The glass roof should be oriented towards the sun in order to capture as much light as possible. If you do not have glass you can use a thick transparent plastic sheet.

How cold frames work

The whole idea of the cold frame’s structure is to protect the plants from the harsh conditions of late autumn, winter, and early spring. It shelters the green life from snow, rain, strong winds, hail and ice. Thanks to the window roof it also collects sunlight and warmth, keeping them inside the frame for a longer time. A cold frame structure usually keeps a difference of 5 to 10 degrees between the inside and outside environment.

You place the seeds inside the frame and they grow into plants, resistant to the cold weather. Still, the collected heat needs to escape in order not to fry out your crops. The best thing you can do is to install a vent with a closing mechanism. Opening it every two days would be enough.


  • Can be used when you don’t have enough space for a greenhouse;
  • You would love to have an early start on the outdoor growing season or extend your crops’ life after the summer is over;
  • You can use it to protect dormant plants until spring comes;
  • Cheaper than a greenhouse;
  • You want a mobile solution for growing plants in winter;
  • You can build two types of cold-frames (brighter or shadier spots can help raise different plants – e.g. vegetables or cuttings).
  • You can design your cold frame according to your own needs. There are no limits when constructing one so you can use your full imagination.


  • It falls behind glasshouse or a polytunnel because they give you the option to actually walk in and manage the growing conditions;
  • There’s less volume of air and there’s no buffer that will negate the effects from temperature amplitudes;
  • Humidity is also a more severe problem due to the less air in cold-frames rather than in polytunnels or greenhouses;
  • It keeps the soil dry so you need to have a very strict schedule of watering the crops;

Cold frames during Spring

The cold frame is perfect if you want to harden young plants. To harden them means to acclimatise them to harsher weather conditions, higher or lower humidity and increased air movement before it’s time to plant them outside. The cold frame will serve as the middle stage when you are transferring the plants from inside your house to the garden. The frame is a controlled environment so you can use it however you need.

Cold frames during Summer

Using the cold frame in the summer allows you to provide certain plants with more heat before the season actually starts. This is very useful when planting, for example, tomatoes and chillies. The increased warmth from the cold frame will encourage and speed up their growth.

Another use for it during Summer will be propagating plants. No surprise heat waves or rainy days will be able to interrupt your gardening plans when you are using the cold frame. You can start from seeds, semi-ripe cuttings or young plants and adjust the conditions according to the needs of your crops.

Cold frames in Autumn

In the Autumn cold frames will protect the young plants and cuttings from unpredicted weather conditions like early snow or night frosts. You will also be able to extend your harvest season with at least 4 weeks.

Cold frames in Winter

You can use your cold frame in winter to prevent alpines from rotting by shielding them from the rain and snow. You can overwinter the fresh annuals and keep them until spring comes. If you want to add some extra protection, you can place a layer of bubble plastic on the inside. It will protect the plants from frosts but it will reduce the light and ventilation as well.

Cold Frames

Cold frames can offer you most of the advantages you can get from a greenhouse. But let’s take a look now at the main differences which will determine your choice in the end.

You will get the same warming effects from a cold frame as a greenhouse but without the option to use an extra heater when the weather is too cold. There is simply not enough space to do so. Cold frames are not suitable for the whole life cycle of a plant. It can only extend the harvest period or give the green life an early start.

The space inside is very limited. In addition to their small size, cold frames are usually built very low so you cannot use racks and you wouldn’t have any floor space. Cold frames can be designed as per all your special gardening needs.

At first glance it may look like cold frames are just the smaller versions of greenhouses, even inferior sometimes. But bear in mind that they are specially designed for different purposes such as germinating, something you cannot do in a greenhouse. They are also perfect for small gardens and people who do not have the resources or the need to maintain a whole greenhouse. It’s cheap to buy, easy to build, easy to maintain and will fit perfectly no matter how small your garden is.