Garden Cold Frames
A garden cold frame is one of the best ways to get an early start on your seed starting and plant growing season. A cold frame is really nothing more than a miniature greenhouse. Cold frames are transparent which allows the sunlight to come in, however they also help to protect your plants from frost and harsh environmental elements.
I personally use my cold frame for hardening off my plants and seedlings. It cuts down on my time transporting plants for indoors to outdoors. I don’t have to babysit my plants as often when I put them into the cold frame and allow them to “do their thing”. In this gardener’s humble opinion, if you’re serious about your gardening a cold frame is one of the best single gardening investments you can make.
However, not all cold frames are equal. When purchasing garden cold frames, the things you need to consider are:
Size and Portability
It would be nice if you can have a one-size-fits-all cold frame. However, not all cold frames can be suited to your plants and purpose. For example, a small plant (or plot) must be fitted with a small cold frame to conserve heat and energy. Big cold frames suit large plants and plots best as it gives your plants ample room to grow. Cold frames, on average, are mostly 1 foot tall, with some taller varieties available (about 3 feet). You also have to think about the size of your cold frame from front to back. Most cold frames are about 2 feet, while others go barely beyond 3 feet.
One more thing to consider about size is how it will help you tend to your plants easily. A small cold frame may prevent you from tending over corners, while large frames may limit your reach in different areas in your plot. You also have to think about how large your area is, or you may find yourself holding on to a cold frame that does not fit in your garden.
Do you have the need to move your cold frame from one area to another, or are you limited to just one area or location for your garden? A large, heavy set cold frame can be difficult to move around, while a small cold frame made of light materials can be easily assembled and dismantled at will without any difficulty in storage and transport. Aluminum, though offers less insulation, can be easily relocated in different areas with each changing season.
Weather, pets, kids, and the elements can be your cold frame’s undoing. Wood is good for dry weather, insulates better, and lasts longer compared to metal frames. If you wish to buy a wooden cold frame, choose hardwoods such as oak over timber. Timber is cheaper, of course, but oak can service your plants better and longer. Regardless of whatever type of wood you wish, do look for the ‘FSC’ mark along with the product name. This stands for Forest Stewardship Council, and ensures that the wood used for your cold frame has been harvested sustainably and responsibly.
Ease of Assembly
When purchasing your cold frame, check to see if instructions are included as there are some manufacturers who think that their cold frame is child’s play and neglect to include instructions, either online or in print. Ask if your cold frame can be assembled easily by yourself, or if you would require the assistance of a fellow gardener, or an expert.
Different manufacturers use different materials for building your cold frame. Different gardening enthusiasts have different opinions over which material is best suited for your gardening needs. Let’s start first with the covering of your cold frame.
Cold frame covers can be made up of glass and plastic such as polycarbonate, polyethylene film, acrylic, or fiberglass. Glass cold frame may look good as you can easily look at how your plants are doing without having to lift the cover. However, it provides poor insulation, has low impact resistance, and can result in plant burns if hit by direct sunlight.
- Plastics are a good choice if you have pets, children, hail storms, and other conditions that would normally shatter the brittle demeanor of glass. One particular substitute is polycarbonate, a new addition to cold frames. It’s almost as transparent as glass, UV coated, and is more durable against impact and even fire compared to other types of plastics. Polycarbonate comes in single, double, and triple wall thickness. Single wall is the cheapest, more appealing. In comparison, double walls provide better strength and heat retention. Triple wall, on the other hand, provides better light diffusion and is excellent in heat retention. Of course, it goes without saying that the triple wall is far more expensive and durable compared to the three, but it can last for years and will save you quite a bit on heating cost.
- Now, if you wish to grow crops commercially through cold frame gardening, then you may want to try out polyethylene film. It may have a short lifespan compared to other plastic materials (3-5 years), but it is relatively cheap, can be replaced easily, retains heat well, and provides high light transmission.
- Fiberglass retains more heat compared to glass, but does so in a lesser degree if measured up against the previously stated glass alternatives. It does have UV coating, but turns yellow once the coating is baked off by the sun within approximately 6 years.
Cold frames can also be made up of wood, aluminum, or galvanized steel.
- Galvanized steel is popular because of its low cost, strength, and durability. Because galvanized steel is naturally strong, less material is used to building your cold frame. Less material, less shadow. The galvanized steel that is used to build your cold frame must be specially manufactured for outdoor construction in order as this lasts longer against high humidity and fertilizer effects.
- Aluminum is lighter than steel, and used mostly with glass as well as polycarbonate because of its flexibility. Although aluminum is not as strong as steel, it lasts longer because it is rust proof, rot-proof, and less prone to UV effects. Aluminum is mostlyshaped in a way to help boost its strength without having to increase its size to prevent shadowing as much as possible.
- Wood is popular for cold frame gardening because of its stylish look and it retains heat better compared to steel and aluminum. However, moisture and humidity can be your wooden cold frames’ undoing, including the effects of fertilizers. Be sure to look for redwood or cedar as they last longer and are usually pest repellant. You can increase its lifespan by applying sealants or stain, but do check carefully whether or not the sealant is good for organic gardening. Remember, if any type of chemical touches the soil of your garden, your gardening practices are no longer considered sustainable. Also, wood is heavier and bigger if put side by side against metal frames, so you will have a problem with shadowing.
- Plastic is often used for portable cold frames, and it is getting more and more popular among gardening enthusiasts. Plastics are highly flexible, last longer (10-15 years), and highly popular because of they are by far the cheapest of all the frame materials. It’s also very light, making it the best choice of material for portable cold frames. Of course, metal wires are used to reinforce plastics for larger cold frames. Although plastics result in lesser heat loss compared to wood, the heat of the sun can lead to deterioration after 20 years or so with the presence of UV coating. In order for plastics to support the entire frame, a larger size may be required for set up that result in increased shadowing.
Consider what you are getting with your garden cold frame when comparing for the price. Does it come with a warranty? If yes, how many days can you return an unused item, or how many years can you use your cold frame and expect technical support if you encounter problems? What was the material used for creating the frame, panels, and lids?
As the saying goes, you get what you pay for, and that holds true for most cold frames. Cheap cold frames can be unstable, weak, and provides poor heat retention. Most expensive cold frames, on the other hand, are stronger, hold their shape and appearance longer, and regulates heat better.
Transparent lids in cold frames are called “lights” as it allows the sun to reach the plants while offering protection against the rain, wind, and snow. There are three types of light designs to choose from: hinged, sliding, and winged.
Hinged lights are cold frame covers that you lift up and prop against a metal or wooden stick to keep the frame open. It is good for areas that receive a lot of rain because it prevents water from reaching into the plants even if the lid is opened as rain water slides over the slope away from the cold frame’s opening. It’s a very popular design because of its ease of use, particularly in tight or small areas. The problem most gardeners have against hinged lights is that it crashes against strong winds, which often results in broken or shattered lights.
Sliding lights, on the other hand, are best for windy locations. Unlike hinged lights, this design allows you to slide the panel either partially or completely off from your plants. Cold frame greenhouse designed with this type of lights, however, does not shelter your plants against rain or snow.
Winged lights offer better reach at the sides as the panels open in opposite sides, allowing better reach and access to plants on either sides. Since they are also hinged, the problem is, of course, wind. If you plan to purchase this type of garden cold frame, check first if you can access both sides and there is nothing that will interfere with opening and closing the lights.
If you wish to harden or over-winter a number of plants in a small area, then a double-decker cold frame may be best for you. Depending on how tall or how cold winter is in your area, you may want to check if the cold frame can or requires additional insulation for preventing heat loss.
Location (Where will you be placing your cold frame)
Will you be placing your cold frame against a wall? If you wish to do so, you must consider the material of your lights and side panels to prevent too much heat from getting trapped inside the cold frame. If you cannot choose the right material because of budget concerns, provide shelter by placing plants that will cast a shade during the times when the sun is at its hottest. However, do make sure that your chosen wall does not cast a permanent shadow on your cold frame.
Your chosen location should give you ample room to kneel on each side of the garden cold frame so you can tend to all your plants with ease. I know it should be common sense, but I know of some people who were so excited about their cold frame that they unwittingly forgot about this and got a frame that is a bit larger than what they wanted. If you are not sure about the size, then measure how much area you need on the sides for kneeling or crouching while considering surrounding structures that can limit your access such as trees, plots, walls, or shrubs.
Some cold frames have heaters installed to provide a better controlled environment for your plants, so you have to check if your chosen cold frame will fit in an area that is closes to your electrical outlet. The cold frame should also be placed near your faucet or water supply so that you can easily water your plants. Have pets and children that are constantly running around your garden as if it’s under siege? Find a location that is away from all that activity because even the toughest cold frame will not stand long against the onslaught of baseballs, footballs, and odd balls.
Here are some of our reviews and recommendations for garden cold frames. I’ve spent a great deal of time reviewing all price ranges and sizes of cold frames, and have made every attempt to give my honest opinion. Some of these cold frames may currently be out of stock, however as we are quickly approaching the seeding and planting season more and more will be quickly restocked, so either put your name of their waiting list or check back frequently for current stock status.
Juwel 1000 Cold Frame – Price: $130.50
For the price, this is a good choice for a medium range cold frame. The two major complaints we were able to determine about this cold frame were difficulty in assembly and some reviewers felt it was flimsy. The assembly itself has been revised since many of these reviews were written, and you can review the assembly instructions plus an instructional video to determine for yourself how difficult you think it is.
As for durability, most reviewers felt it was durable. One “Windy City Chicago” reviewer was even extremely impressed with how well it held up during the extremely high winds. Easy to disassemble for winter storage.
39.37″ X 35.43″ X 15.74″
Double-Decker Cold Frame (Aluminum Frame) – Price: $40.00
The advantages of this cold frame is that the aluminum will not rust, plus the twin walled polypropylene provides a high level of insulation.
However, you need to keep in mind that at the price range of $40 you’re not going to be getting a heavy duty cold frame. This one is lightweight and may not hold up to some extremely high wind conditions.
It does come with 6 seed starting trays, and since it’s double decker you can have the advantage of placing “seedlings” on the bottom deck and starting new seeds on the upper level.
15.7″H x 30″L x 15.4″W
Single Cold Frame (Galvanized Frame) – Price: $49.00
New gardeners will love this cold frame because of its ease of use. The good thing about this is that it’s made up of durable galvanized steel that can last for several winters or hardening, with the lids made up of clear, UV coated material.
Though it may look relatively easy, one reviewer experienced difficulties in assembling the cold frame by himself. With some help, though, the cold frame was quickly assembled and showed promise in lasting for a long time.
Size: 15″H x 36″W x 24″D
Juwel Double Cold Frame – Price: $159.99
If you are in a hurry to start your cold frame gardening, or have some difficulty holding handyman tools, then this may be the perfect cold frame for you. This cold frame comes with a patented ‘easy-fix-click-system” that makes both assembly and disassembly a breeze.
The Juwel Double Cold Frame comes in a winged light design that has two height adjusters for support and stability. It also has four window brackets that hold the windows open and prevents the lid from flying along with a heavy gust of wind. The child-proof rounded edges makes the Juwel Double Cold Frame relatively safe for children.
Peak Height 17” Comes with “child-proof” rounded edges, with 8mm Polycarbonate panels that give extra durability that can carry as much as 6 feet of snow.
48”L x 40” W x 12”D
Juwel Bio Star 1500 Deluxe Cold Frame – Price: $389.98
This is a larger version of the Juwel Double, fit for a serious farmer with large gardening needs.
Reviewers like this for cold frame gardening because of two things: you can grow crops all year round, and because of the optional thermal control that adjusts the openings of the lights to allow cool air to circulate. All reviewers like this particular option especially during the summer when temperatures are too high. This is very helpful for those who are not certain if the heat inside the cold frame is adequate or too much for the plants, and one reviewer finds this very useful as she’s working and no one is at home to check her plants. The “no-drip” coating system prevents condensation from forming on the leaves, thus preventing the growth of mildew.
This added thermal regulation is a bit expensive as a special thermometer is needed to signal the arm to raise or lower itself accordingly. Still, it’s a worthy investment as the plants continue to thrive all year round.
Size: 59″ x 31.5″ x 19.68″
Solar Bell Single Cold Frame (3 Pack) – Price: $35.00
The Solar Bell Single Cold frame is ideal if you are trying to germinate a very small batch of seeds, or if you wish to protect a very small seedling or plants during heavy rains or snow. The material is made up of high quality plastic that is as clear as glass, with an adjustable vent at the top to help you control the temperature inside the cold frame.
Since it’s very light weight (about 1lb), it may topple over with just the slight gust of wind. However, this can be easily remedied with ground stakes or strong twigs.
Size: 13 inches in diameter (base), 10” H.
Victorian Greenhouse Decorative Cold Frame – Price: $55.95
The Victorian Greenhouse Decorative Cold Frame brings over-wintering and hardening to a new level. What makes this interesting is that your seedlings will be protected inside a miniature house, sheltered from the wind and cold. The loop handle makes it easy to lift and tend to your seedlings for watering or transferring to a better sunny location as the days transition from one season to another.
Reviewers like it because it brings an interesting accent to a home or garden. You would think that a bird lives inside the house and not potted plants. However, because of the numerous square panels, it is unavoidable that you get some shadowing inside the cold frame. Your best solution is to put it in a sunny spot to get the most sun and away from a shade.
Made with glass and cast iron with a rusted finish for an aged and beautiful Victorian look.
11.4″L x 9.1″W x12.4”H
Advantech Garden Cold Frames – Price: $58.95
The Advantech Garden Cold Frame is made up of durable fir lumber. This cold frame greenhouse is loved by reviewers with small spaces as the compact design makes it perfect for small areas like balconies and terraces. The lock lid design also gives it better control against accidental opening and closing due to sudden gusts of wind.
One reviewer, however, is skeptical about the construction of the design because it’s very lightweight, about 11lbs. Others do not have find any issues with this, and the light weight construction can actually be your blessing if you have the need to move your cold frame from one area to another.
Size: 15” H x 39” W x 23” D
Riverstone Genesis 3′ x 3′ Cold Frame – Price: $89.99
Design and functionally meet together in this Riverstone Genesis Cold Frame. The rust-resistant frame is painted with a rich forest green color that makes it an interesting focal point in your garden. The opaque windows are made up of UV protected plastic resin that allow light and heat while protecting your precious plants and seedlings against sun damage. The lids are large, allowing easy access to your plants. Not only does this cold frame protect your plants from frost, it also keeps them safe from pests, deer, and rodents that always get to be the first to eat your crops before you do. The Riverstone Genesis Cold Frame is also designed for easy storage and portability when not in use.
One reviewer liked the Riverstone Genesis Cold Frame because he finds the design most interesting compared to other cold frames in the market. All reviewers were able to assemble the unit within 15 minutes, which holds true to the manufacturer’s claim of easy assembly.
If you wish or require to keep your plants inside a cold frame for a longer period, get this one as the Riverstone Genesis Cold Frame has one of the highest peaks, about 19 feet in height.
18.9″ H x 39.4″ W x 37.8″ D
Sunshine Cold Frame Starter Kit – Price: $139.99
This is another miniature greenhouse that is perfect for those who are just trying out cold frame gardening for the first time. It’s made up of weather and pest resistant redwood and double-walled polycarbonate panels, yet light weight enough to be moved around your garden if necessary.
One reviewer is skeptical over how strong the lid would stand against wind since it only has one locking hinge to keep it in place. However, the double-wall polycarbonate panels are guaranteed to not crack or shatter just in case the lid got snapped shut accidentally.
Good for direct soil or container gardening.
49″ W x 25″ L x 16″ H
Single Garden Cold Frame - Price: $49.99
This cold frame acts like a miniature greenhouse that can help you grow or harden your plants either directly from your garden or in pots. The structure is made up of Crystal-clear polycarbonate SnapGlas™ roof panels that allows maximum light transmission and visibility. The body is made up of hard polypropylene panels supported by corrosion resistant aluminum. The Poly-Tex Single Cold Frame Greenhouse comes with hold-down spikes that will enforce your cold frame on top of a wooden or concrete base.
The instructions for assembly are fairly simple. Some of the reviewers, though, had problems with assembly as the side panels seem to bulge out, causing some heat to escape. However, there are also some reviewers who are satisfied with the product and did not encounter bulging panels. They reported that as long as the assembly is done right, all the panels will fit together and the lid will close over the cold frame nicely. Sloping lids permit maximum sunlight and rain runoff.
Size: 41” W-18” H – 22” D.
Double Garden Cold Frame – Price: $89.99
Last but not least in our suggested line of garden cold frames is this Double Garden Cold Frame. It comes in a winged lid design that allows access to your plants easily. The panels are made up of high-impact durable panels that can withstand heat, rain, hail, and heavy snow.
Reviewers like this because the lid is clear, allowing them to see the plants without having to open up the lid. You won’t have any problems with high winds knocking off the cold frame because there are pegs that can hold down the corners when needed.
One reviewer felt that the materials used for the Double Cold Frame are not sturdy enough because the frame feels a bit light and flimsy. The light design is due to the use of aluminum, which is known for its light yet corrosive resistant property while capable of keeping its shape and form for years. The frame comes with a 5-year warranty, meaning you can and should expect your garden cold frame to last for years. Sloping lid allows maximum sun exposure and rain runoff.
41” W x 21” H x 41” D.
If you have the tools and the skills and want to build your own cold frame, then you can get a great description and visuals on how to build a cold frame greenhouse here. By building your own wooden cold frame you get to be in charge of the size and durability.
Have you ever used a cold frame? If so, would you mind sharing your thoughts to help other fellow gardeners who are considering purchasing a cold frame. Thanks!
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