The humble cold frame is a handy little trick you can use to extend your vegetable growing season through the winter months. Imagine a greenhouse, but way smaller and easier to manage.
Cold frames are also a great way to help fragile seedlings transition from indoors to outdoors. Many gardeners use cold frame gardening as a way to get a jump on spring crops as you’ll be able to protect those young seedlings from any late and unexpected winter weather.
These contraptions don’t take up too much space, can be modified to fit into your current vegetable garden, and can be portable. Read on to discover our top picks for the best cold frame on the market.
Backyard Boss Top 5 Cold Frames for Your Veggies in 2021
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Why You Can Trust Us
At Backyard Boss, we celebrate any excuse to spend more time in our backyard. We know that vegetable gardening doesn’t have to be a fair-weather activity. When winter shows up, we still need to be able to grow those tasty vegetables. Besides, having a cold frame is a perfect excuse to spend more time in the backyard. This is why we’ve created an extensive catalog of cold frame and greenhouse articles to keep you informed.
After sorting through all the available products and eliminating those of questionable quality and value, we found a range of options that suit a variety of needs. Below are the main criteria we used to choose our top picks.
- Portable or permanent: Whether you’re looking for a portable device to grow some greens in the dead of winter or a permanent structure to give you another growing season, we added something for you.
- Budget or premium: Whether you have a few bucks to spare for your latest gardening addition or looking to invest in something that’ll last years, we have you covered.
- Range of features: We included cold frames with a range of features so that you can find something that suits your particular needs.
Best Premium Option for Small Spaces
This premium cold frame is built with top quality materials and attention to detail. Keep the cold and the pests out with the built in fly screen
- High quality materials
- Insect screen
- Double thick polycarbonate sheeting
- Assembly instructions in German
- Assembly may be difficult
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Why We Like It: The "premium" in the name of this product is no joke. This German-designed cold frame is packed with clever little features to make your winter gardening a breeze.
Take a look at the insect screen installed beneath the sliding opening. This means you can give your vegetables a breath of fresh air without worrying about pests or heavy rains damaging your plants. Or open the whole top for easy access.
The polycarbonate material that it’s made of is double the thickness of regular cold frames. This means double the insulation and protection against the elements.
Who Should Buy It: For those of you living in particularly harsh winters, the thickness of the polycarbonate sheets that this unit is made of may give you the insulation that you need. It’s also small enough to fit into tight spaces like balconies. The insect screen is a nice touch for those struggling with pests.
Best for Raised Beds and Harsh Climates
This well insulated cold frame comes with an automatic opener to keep your vegetables thriving in an optimum environment no matter the weather
- Double thick polycarbonate sheeting for added insulation
- Automatic opener for climate control
- Suitable for harsh climates
- Difficult to assemble
- Unclear directions
- Packaging doesn't provide sufficient protection during shipping
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Why We Like It: This larger version of the BioStar also differs in its features. There’s no insect screen, but there are more windows as well as an automatic opener on one of them. This means you can be sure that your plants are receiving adequate ventilation without lifting a finger.
The extra-thick (8mm or 5/16 inches) polycarbonate sheeting means superior insulation in the harshest climates. This larger version might fit perfectly over your raised beds. So you won’t have to shuffle your plants around when winter arrives. Just place this cold frame over your already existing beds and be done with it.
Who Should Buy It: If you’re looking for a premium cold frame that’ll keep your veggies warm for at least the next 10 winters, look no further. This cold frame is large enough to place directly over raised beds and light enough to move around easily.
Best Portable Cold Frame
This portable cold frame is a simple solution to keeping your plants toasty over the winter
- Lightweight and easy to move
- Small enough for your balcony
- Easy to assemble
- May need to anchored in heavy winds
- Not much space for a lot of plants
- Seems to be some quality control issues
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Why We Like It: This portable cold frame unit from Giantex gives you a solid foundation for entering the world of cold frames. Assembly shouldn’t take you longer than 30 minutes and the only tool you need is a drill.
You can easily lock the lid in the desired position so that you can maintain the optimum environment for your vegetables. The compact size of this unit means you can squeeze this into small spaces such as balconies.
It’s been reported that this cold frame keeps your vegetables about 10 degrees Fahrenheit warmer than ambient temperature. You can increase the temperature by adding a few lights inside the unit or by placing it in a sunny spot during the day.
Who Should Buy It: If you need a compact solution for growing a small number of vegetables during a cold winter, consider this cold frame. It’s small enough to fit on a balcony and light enough to move around whenever you need to.
Best With a Stand
This raised cold frame comes ready to paint or stain. The added display shelf means that you can overwinter your vegetables in style
- Raised so no bending over required
- Ready to paint or stain a color of your choosing
- Lid locks open
- No automation on lid
- Limited space
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Why We Like It: No raised beds? No problem. This cold frame stands on a sturdy frame that means you can attend to your overwintered veggies without bending over. The additional storage shelf below is a great place to put hardier plants on display or to store tools and other gardening gear.
Despite its good looks, this cold frame also does the job of keeping your plants warm. The top locks open for easy access or locks closed for superior protection.
Who Should Buy It: If you want a cold frame that doubles as a display shelf, you’re in luck! The product arrives ready for painting or staining, so you can customize it to fit with your aesthetic.
Best for Moderate Climates
This low maintenance cold frame is quick and easy to move so you can cover your vegetables before the next cold snap
- Cheap
- Light and easy to move
- All sides open for ventilation
- Will need to be anchored in high winds
- Not suitable for harsh winters
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Why We Like It: Lightweight, cheap, and effective in moderate climates. This cold frame kit looks like a mini greenhouse and the size is adjustable to fit your specific needs.
You can easily open it up completely and keep the covering out of the way with ropes. This means that you can keep it in place all winter and only close the sides when you’re expecting cold weather.
Easy to move and adjust, this cold frame will provide much-needed protection during cold snaps and frosty mornings. It will probably not do so well in heavy snow conditions.
Who Should Buy It: If you live in a place with moderately cold winters and only sometimes need protection for your vegetables, this product might be what you need.
What’s the Difference Between a Cold Frame and a Greenhouse?
Image credits: Exaco via Amazon
In one word: size.
A cold frame is typically a small structure used to extend your growing season into the harsher winter months. Opening or closing the lid is usually the extent of the climate control with cold frames, unless you decide to get fancy and add lights or heating elements. Cold frames are also a useful way to help seedlings transition from inside to outside. They are a great halfway house between inside and outside for sensitive seedlings.
Greenhouses are usually a lot larger than cold frames and are used to grow plants year-round. The climate control is much more sophisticated with automated ventilation fans and heat sources creating an optimum environment for whatever plants you wish to grow.
An easy way to remember the difference between cold frames and greenhouses is that greenhouses are larger, more permanent structures for year-round growing. While cold frames are smaller units designed to extend your growing season into the harsher winters.
How to Choose a Cold Frame
Not all cold frames are created equal. Which means there’s something out there for most situations. It’s important to know what you need from your cold frame before you buy or build one. The features below are a good starting point for the decision-making process.
Type
This is the first thing you should be clear on. Do you need a cheap solution that fits over your existing garden beds? A few PVC hoops with clear plastic sheeting over the top could do the job for you.
Are you looking for something a bit more permanent? Maybe a sturdier frame with polycarbonate panels will be up to the job. If your winters are particularly harsh, consider going the premium route with double-thick polycarbonate panels and automatic opening for ventilation.
Size
This is often the biggest limiting factor in your decision. The trick is to use your space as efficiently as possible so as to limit wasted space. Building your own might be the best option if you have a weird niche that needs filling.
Otherwise, there are plenty of options across all size ranges available on the market. From small portable cold frames that resemble simple row covers, to human-sized cold frames that border on greenhouses.
Remember that cold frames don’t have to be in your vegetable garden and can even be stationed inside your house if there’s sufficient sunlight. So if you’re short on space, be creative. Any corner can be a food-growing corner if you try hard enough.
Materials
The simplest cold frames are any type of plastic sheeting fastened to a frame of some sort. These are OK for temporary use but probably won’t do much good in severe weather.
Glass is another popular material for cold frames due to its availability and transparency. The problem with glass is that it’s fragile. Hail will shatter glass in no time and a large amount of snow will surely do the same.
Polycarbonate sheeting is used in most premium cold frames. This is because polycarbonate is stronger than glass with superior insulation while still allowing UV rays through. It is expensive, but if you can afford the upfront investment, you should be set for many years.
Image credits: Lettuce Grow via Unsplash
Weight
If you plan on moving your cold frame between the seasons, you probably want something on the lighter side. You will need to anchor lighter cold frames so that they don’t blow away.
If you plan on leaving your cold frame where it is on a permanent basis, then it won’t be an issue if it’s heavy. The added benefit of a heavier cold frame is that severe weather won’t blow it away or topple it over.
Portability
Sometimes you only need a cold frame when there’s frost on the forecast. If you’re looking for a portable cold frame, then it goes without saying that it needs to be light and easy to move.
It would also be helpful if you could easily dismantle the unit for easy storage when it’s not in use. Nobody wants a bulky cold frame hogging all the space in the shed.
Features
The added available features are endless. If you’ve done your homework you’ll know which ones are necessary and which ones you’ll never use.
Having a hinged lid that locks open is an important feature for ease of use. Gardening typically requires two hands, so using one to hold the lid open will lead to frustration and maybe even a bump on your head.
Some cold frames come with lights inside. Or you could easily fit a light to your existing cold frame if needs be. This will raise the temperature inside the cold frame and could be an important feature in harsher climates.
Another nifty feature we found in some products is an automated opening arm. This is an arm that is fitted to a hinged lid or opening. It’s then connected to a solenoid and thermostat.
The result is that when it gets hot in there, the thermostat tells the solenoid to open the lid so that hot air and humidity can escape. Once the temperature drops, the lid closes again. This will save your vegetables if you forget to open the lid on a warm day.
Image credits: Markus Spiske via Unsplash
To Wrap Up
Our top pick goes to the Exaco BioStar 1000 Premium. The thoughtful design and clever engineering will give you peace of mind. The insect screen and double-thick polycarbonate sheeting make it stand out. It's large enough to fit a variety of vegetables in the growing space inside. It’s also small enough to make it easy to move when the time comes.
This cold frame doesn’t have a bottom. This means you can easily put it in your existing garden beds to protect the plants that are already growing there. All of these features combined with the excellent build quality make it our top pick for cold frames for your vegetables.