Give your plants and seedlings the best start in life, by growing them inside a cold frame.
Cold frames are low, enclosed structures, designed to protect plants from harsher weather. They are similar to a greenhouse, but generally smaller, and offer limited control of the internal environment. However, for starting seeds off in spring, they can be all you need, and they require very little maintenance.
These structures are usually made from wood, plastic or glass. They have 4 walls, and a roof or front that can be opened, allowing access to your plants, as well as ventilation. When choosing a cold frame, bear in mind that its height should be greater than the mature height of the plants you intend to grow inside it.
To help you choose the best cold frame for your seedlings, we’ve selected our 5 favourite options on the market, and explained exactly why we think they deserve a place in your garden below.
Last update on 2021-07-31 / All Pricing & Imagery from Amazon Product Advertising API
These cold frames are hard-wearing, insulating, and will take great care of your plant babies.
Our top-rated cold frame is compact, durable and offers easy access to plants – and it’s highly affordable too
If you’re searching for the best cold frame for your garden, we highly recommend this Steel Frame Poly Tunnel from Outsunny.
This top-rated low greenhouse measures L 180 x W 90 x H 90 cm, so it’s small enough for use on balconies and patios. The structure is compact and lightweight, so it can be easily moved and repositioned as required – although you will likely need to bolt it down, to prevent it moving in the wind.
It consists of a powder-coated steel frame, with plastic connectors designed to withstand the elements, and a UV-resistant, PE mesh cover. The cover provides plants with shelter from wind, UV rays and light rain, whilst still allowing through the essential oxygen and sunlight that plants need to grow.
The cold frame has zip-opening, roll-up doors, offering the user easy access to their plants. There is at least one report of the cover coming away from the seams, but if this does happen to you, it should be easily fixed with superglue.
We think this is unlikely though, as overall the cold frame seems great quality. It’s also a highly affordable option, and offers excellent value for anyone with a small garden, looking to give their plants the best start in life.
- Durable, powder-coated steel frame.
- Plastic mesh cover protects from wind and rain.
- Mesh still allows essential sunlight and oxygen through.
- Roll-up doors with zip fastenings offer easy access.
- Lightweight and easy to move around.
- Small size is suitable for balconies and patios.
- Some reports of cover coming away at seams.
- Requires some self-assembly.
Our best value cold frame offers excellent ventilation and shelter for plants – for an unbeatable price
The cold frame that we think offers you the best value for money is this Garden Point Growhouse.
At L 180 x W 140 x H 94cm, it’s slightly wider than our top pick, so you’ll be able to fit more seedlings inside. It’s made from a galvanised steel frame, with a 140 g/m2 PE cover. This cover provides plants with UV and weather protection, whilst still allowing sunlight and oxygen through.
Roll-up side windows allow for further ventilation if required, and the main roll-up door offers the gardener easy access to their growing plants. An internal fly net functions to keep insects and birds out, even when the window vents are open.
As with our top pick, there is some self-assembly required, and this can be a little tricky. The structure doesn’t feel the sturdiest, and we would recommend pegging it securely to the ground, and perhaps reinforcing the connectors with tape, to prevent damage in harsher weather. The cover, though, is surprisingly durable.
Overall, this is a decent quality and well-sized cold frame, and you’ll be hard-pressed to find anything better for this money.
- Durable, galvanised steel frame.
- 140 g/m2 PE cover provides UV and weather protection.
- Roll-up window for air circulation.
- Internal fly net to keep insects and birds out.
- Compact size – perfect for small gardens.
- Great price – this is our most affordable cold frame.
- Structure feels a little flimsy.
- Self-assembly required.
A small but stylish cold frame, made from FSC-certified timber, and ideal for balcony use
Our next product, this Gardman Limited Wooden Cold Frame, offers a different design to the previous two, and what we believe is a more stylish aesthetic.
This plant shelter boasts a wooden frame, made from FSC-certified timber. Note that, unfortunately, the wood is not pre-treated, so some weatherproofing will be required, to protect it from rotting when exposed to the elements.
The frame is covered in twin-wall polycarbonate, to shelter your plants from rain and frost in spring (although you will need to add heating to protect plants from harsh winter frosts). Locking stays provide ventilation, and the hinged lid allows easy access to your seedlings.
Measuring L 100 x W 65 x H 40 cm, this is our smallest cold frame yet, and is ideal for a small balcony or terrace – although bear in mind that it won’t be able to accommodate as many plants.
Some self-assembly is required, but it shouldn’t take much more than 15 minutes to put together (you will need to provide a screwdriver for this purpose). This is a great choice for city dwellers, and those with limited space, who don’t want to miss out on growing their own plants.
- Frame made from FSC-certified timber.
- Hard-wearing twin-wall polycarbonate body.
- Compact size is ideal for a balcony.
- Hinged lid for easy access.
- Locking stays for ventilation.
- Attractive design.
- Wood does not come pre-treated, so will need weatherproofing.
- Small size means you won’t be able to fit as many plants.
- Requires self-assembly.
This timber cold frame has 2 opening lids, and comes pressure-treated, to protect against rot
Our penultimate cold frame is another timber model, with a similar design to our previous pick, and Perspex glazing.
However, this Timber Cold Frame from Rowlinson Garden Products differs, in that it has two independently opening lids, allowing you to access half of your internal plants, without disturbing those on the other side. The lids can be held open at 2 height settings, to provide varying ventilation for your seedlings.
Unlike our previous model, the wooden frame on this one is pressure-treated, to protect it against rot, so you won’t need to do this yourself (at least, not immediately – it’s always a good idea to re-treat wooden garden furniture regularly, to prolong its life).
This cold frame measures L 102 x W 81 x H 38 cm, so it’s another fairly compact option, that won’t take up too much space in your garden. You will need to assemble it yourself, and this might not be the easiest task, as a few users report missing or poor instructions and/or screws.
However, once you’ve got all the necessary hardware, and managed to put it together, this cold frame is a solid and high-quality option, and is great for starting off your new plants in a stylish, sheltered environment.
- Thick timber frame.
- Sturdy, solid design.
- Wood is pressure-treated, to protect against rot.
- Two independently opening lids.
- Lids can be held open at 2 varying heights, for ventilation.
- Some users report missing screws and poor instructions, which can hinder assembly.
- Heavy – can be cumbersome to move around.
- Not the most affordable option.
A tall, timber cold frame, with durable plastic glazing, and multiple access options
Cost: Price not available
The final cold frame we recommend is this Plastic Cold Frame by Spear & Jackson.
This one measures L 69 x W 48.5 x H 120 cm, and is the only cold frame on our list that is taller than it is wide. This might make it ideal for elderly users, or those with bad backs, who want to avoid too much bending down.
Environmentally-conscious gardeners will be pleased to know that the cold frame is made from FSC-certified timber, from sustainable sources. The wood is pressure treated, to protect it from weathering. Durable plastic panes allow sunlight through to your growing plants – although the glazing is prone to deterioration over time.
It features a hinged opening lid, and 2 doors to the front of the structure, offering multiple ways to access your plants. Internal shelving inside the cold frame means you can easily separate your pots, and fit more plants in.
This isn’t the easiest option to assemble – the instructions could be clearer, and you may need to drill some of your own holes throughout the process, as the pre-drilled ones are sometimes out of alignment. Once it’s together though, the completed structure feels sturdy, whilst still being lightweight enough to move around your garden.
If you need more assurance of the quality of this cold frame, it was a winner of the Great British Growing Award 2018 – so we’re not the only ones who think this is a great choice!
- Frame made from FSC-certified timber.
- Tanalised wood for improved weatherproofing.
- Durable plastic glazing.
- Internal shelves to separate your plants.
- Lightweight and easy to move around.
- Winner of the Great British Growing Award 2018.
- Not the easiest option to assemble.
- Plastic glazing is prone to deterioration over time.
- This is our most expensive cold frame.
Is A Cold Frame The Same As A Greenhouse?
A cold frame is similar to a greenhouse – they are both enclosed structures, designed to protect plants from frost and harsh weather. However, there are a few key differences.
Cold frames are usually smaller than greenhouses – they might only be a meter or so high. In contrast, greenhouses are generally tall, house-shaped structures, that humans can stand up in.
Cold frames offer limited protection on their own, and will usually require an artificial heat source to keep the frost away. Greenhouses typically offer more control over the internal environment, with built-in heating, lights and ventilation – although this is not always the case.
A cold frame can be ideal for starting off seedlings earlier in spring, or keeping plants alive later into autumn. It can also be used for overwintering plants that die off in the cold, and can be revived in spring.
In contrast, greenhouses are a more year-round solution. You might like to move plants from a greenhouse to a cold frame before planting them out, to improve their hardiness.
Do Cold Frames Protect From Frost?
The extent of protection offered by cold frames depends on their design, and location. However, generally speaking, cold frames on their own will offer limited frost protection.
To adequately protect plants in a cold frame from frost, you will usually need to add insulation (such as straw, aluminium foil or fleece) and/or a heat source, such as a hot water bottle or electric heater.
To improve your cold frame’s protective abilities, try to position it in an area with lots of direct sunlight, and ideally some additional wind shelter, for example from a wall or fence. It is also important to remove any ice or snow from the top of the cold frame, so it doesn’t block the sunlight from reaching your plants.
How Tall Should They Be?
There are many different sizes of cold frame available, and it can be difficult to know which one to choose. As a general rule, if you’re using a cold frame to grow plants to maturity, the frame should be slightly taller than the maximum height of the plants, once fully grown.
However, if you’re only using a cold frame to start seeds off in spring, a low height of 15 – 20cm should be sufficient. Make sure to move the plants out of the cold frame before they reach the roof. If you want to grow multiple potted plants, a taller cold frame with internal shelving might be ideal.
April is a freelance writer who specialises in writing about home and garden design and the environment. She is an avid wildlife-enthusiast and adventure-seeker, and feels happiest when in the Great Outdoors.