Updated/Fact-Chacked on May 31, 2023 by Gareth James
I’ve been toying with getting a full-size greenhouse, but I’m not quite ready to commit; maybe next year.
After searching for ‘small greenhouses’, I did consider a lean-to greenhouse, but I thought it might blow away with our recent North East winds! I then came across the idea of cold frames and bought an upright cold frame unit.
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What are cold frames?
Cold frames are mini-greenhouses, generally made of glass with a wood or aluminium structure. They can be simple box structures that sit over plants on the ground or upright, like a glass cupboard, especially for plants.
The cold frame I bought last year, currently being used to store potsBoxed-like cold frames can be moved around and placed in the desired location, whether in raised beds or on the ground. These are better suited for vegetable growers, but at the moment, I’m concentrating on flowering plants.
Cold frames are generally used if you don’t have the space for a greenhouse or need to get some heat into the soil on your beds.
When are cold frames used?
Cold frames have a range of uses throughout the year. In spring and early summer, they help harden off young plants before transitioning them to the garden.
During late spring and summer, they provide extra warmth for tender crops, promoting quicker ripening and larger yields. Cold frames are also great for propagating plants, including cuttings and seedlings. In autumn, they protect plants from cooler weather and mild frosts.
Cold frames can also be used in winter to give alpines protection; you can even add bubble wrap to protect against frost. I’ll keep my dahlia tubers in one this winter instead of my garden shed.
What to grow in cold frames
Many people use cold frames for growing vegetables, like tomatoes, but I purchased one to help me grow flowering plants. I have been growing some seeds with a heated propagator and need a place for the plants to grow once a little taller without planting them out in March/April.
Once we get some slightly warmer weather in March I will move my young plants into my cold frame, then plant in my borders and pots once they are ‘hardened off’.
Types of cold frames
Cold frames come in two main types: flat box cold frames and vertical cupboard style cold frames. Work out which structure best suits your needs, then your budget will determine the material the frame is made of.
Aluminium cold frames – These are lightweight cold frames and best used if you plan on moving the cold frame around to place over different plants. The main disadvantage is their tendency to move around in the wind, but they can be secured in place with pegs.
Wooden cold frames – Wooden cold frames are studier and have a more ‘classic look’. You can buy hardwood cold frames if you want something substantial or a softwood cold frame if you are on a budget. Wooden cold frames come in a variety of shapes and sizes from flat boxes to uprights with various doors and opening panels.
Plastic cold frame – Plastic cold frames can be bought online but are likely to be less durable and not as good as glass for heating up the soil.
DIY cold frames – You can make a simple diy cold frame structure by stacking bricks around the area and placing a pane of glass or plastic sheeting over the top.
DIY cold frameCheap Cold Frame Kits
I have been researching the best cold frames for your money all over winter. As it’s my first venture into using them I didn’t want to buy an expensive hardwood one.
Unless you spend £400+ on a good hardwood one, they are likely to come in kit form; Amazon is great for things like this – cheap and cheerful. The cold frame kits are all easy to assemble with just a screwdriver.
My budget was £100 and under and searched on Amazon.co.uk and Crocus.co.uk. The products below are all cheap cold frames with different structures, I have also included a plastic framed unit.
The links below may affiliate links and I may earn a very small commission if you purchase a cold frame anything from these websites.
FeelGoodUK Large Cold Frame Greenhouse
This is the best looking upright cold frame unit, delivered as an easy-to-assemble kit. We love the ability to have the top shutters open and doors closed for maximum heat without getting humid.
The unit is 120cm high and 100 cm, ideal to sit at the side of a house in a sunny location. The panels are made of PVC with three levels of shelving.
Outsunny Wooden Framed Polycarbonate Cold Frame Greenhouse
This is a great cheap wooden cold frame box with one opening. The cold frame is 100 cm long and is easy to move around your garden.
The product has polycarbonate windows instead of glass, but for around £50 you can’t go wrong. The top door can be fixed in a slightly open position if you want more ventilation and to reduce the humidity. The lid can also be kept open during the day for direct sunlight and closed at night to give young plants protection from any potential frost.
Kingfisher GHWOOD Wooden Mini Greenhouse Coldframe Kit
This is the vertical cold frame I purchased from Amazon, a cheap and cheerful kit. I bought this product as it has the most positive reviews out of all the vertical wooden cold frames.
Plastic Cold Frame Mini Greenhouse Kit
This plastic cold frame unit is probably the cheapest you will find and under £40. It would be ideal in a sunny location against a wall – be sure to secure it though from wind.
Though the cover and zip doors are plastic, the actual frame is made of metal. The product is 63″ tall and has four shelves, enough to hold a substantial number of young plants. This cold frame could easily be packed away when not in use and stored in a shed.
Outsunny Aluminium Flat Cold Frame
Low-cost aluminium cold frame with three roof panel doors that can be opened. The frame weighs 5kg so can easily be moved to new locations as required.
Urban balcony raised bed hood
The Urban Balcony Raised Bed and Hood is a practical solution for balcony gardening, specifically designed to accompany the Urban Raised Bed. I can just see myself in a New York penthouse, becoming a serious balcony grower!
This transparent cover offers plant protection while allowing for early seedling growth. One notable feature is the presence of holes in the top, allowing for convenient watering without the need to remove the hood. Priced from £12.99, it provides a cost-effective option for balcony-growers. You can purchase the Urban Balcony Raised Bed Hood from Crocus and Robert Dyas, ensuring easy accessibility to enhance your balcony gardening experience.
John Green is a 46-year-old graphic designer living in Durham. John is RHS level 3 certified and owns an allotment in Durham.