The Best Cold Frame Greenhouses
Updated: Feb. 29, 2024
Extend the growing season with a cold frame greenhouse. It's more of a box than a house, perfect for protecting seeds and starts from cold weather.
Our editors and experts handpick every product we feature. We may earn a commission from your purchases.
Want to start your seeds early and get a jump on the growing season? There are a couple of ways to do it.
If you don’t have room for an actual greenhouse, stake out an area in your basement or garage and purchase grow lights. If you do have the space, there’s another way: Set up a cold frame greenhouse right in the garden. It uses the heat of the sun to provide an environment that’s five to 10 degrees warmer than its surroundings—similar to the growing conditions 500 miles farther south.
In general, a cold frame is a greenhouse with no heat source. While there are large walk-in ones, the most common are small, and many are portable. They’re essentially one or two-foot tall boxes with open bottoms, clear or opaque sides and transparent lids.
You can set a cold frame directly on the ground or partially bury the sides for extra insulation. Most are built with a slight slope facing south to better catch the sun.
A cold frame is simple enough to DIY, and many people do. But if that’s not your thing, we found the best cold frame greenhouses to suit every type of grower.
via merchant
Best High-End Cold Frame
Juwel Biostar Cold Frame
The Juwel Biostar Cold Frame is made of twin-wall polycarbonate panels for excellent heat retention, with three lids that open and close independently. Twenty inches high, it features a 3- x 5-ft. footprint.
The no-drip interior coating protects plants from condensation, and the unit comes with four corner stakes to anchor it securely to the ground. It’s made in Austria, a country on the leading edge of cold frame technology, which accounts for its high price.
via merchant
Best Budget Cold Frame
Hanover Single Garden Bed Cold Frame
The Hanover Single Garden Bed Cold Frame can do everything any other cold frame can do for about one-third the cost, so it’s a great buy for first-time and experienced growers alike. With an aluminum frame and double-walled polycarbonate panels, the unit is light enough to move around the garden.
Two top panels open independently so it’s easy to access plants, and the 3- x 2-ft. space inside provides plenty of growing room. The roof has adjustable latches for ventilation.
via merchant
Best Multi-Tier Cold Frame
Outsunny Three-Tier Cold Frame
The lean-to Outsunny Three-Tier Cold Frame stands just under five feet tall with a 2- x 4-ft. footprint. The three shelves provide plenty of space to organize your plants and even store garden tools. It’s supported from the back by another structure.
The frame is mostly aluminum with a galvanized steel base, providing strength to resist the wind. The polycarbonate panels admit 90 percent of the sun’s light, giving plants the warmth they need on cold days.
via merchant
Best Wooden Cold Frame
MCombo Cold Frame
If you’re going to DIY a cold frame, you’ll most likely make it from wood. But why bother when you can purchase the MCombo Cold Frame instead?
The three-foot-square base provides lots of growing room. The polycarbonate panels diffuse incoming light and guarantee maximum absorption without overheating.
The two top panels of triangular roof open to provide access from both sides. It’s easy to set up in the garden, on a patio or anywhere else you want to start seeds or tend seedlings.
via merchant
Best Pop-Up Cold Frame
Zenport Cold Frame Greenhouse
The Zenport 4- x 4-ft. Cold Frame Greenhouse comes with an easy-to assemble triangular aluminum frame, plus a vinyl top covering that rolls back for ventilation.
It’s easy to set up over an existing garden bed, providing a controlled microclimate for fragile flowers and vegetables. It lets you to cultivate plants that wouldn’t otherwise grow in your climate zone. It’s lightweight enough to move from place to place in the garden.
via merchant
Best Modular Cold Frame
Delta Park Gable Roof Cold Frame
What happens when you run out of space in your cold frame? If you have Delta Park Gable Roof Cold Frame, you simply add another one with the brackets provided. Each module provides one square meter (39.4- x 39.4-in.) of growing space.
This cold frame features polycarbonate side and roof panels that are adjustable and removable for ventilation, with good light transmission and insulation.
via merchant
Best Hoop-Style Cold Frame
Haxnicks Mini Greenhouse
The Haxnicks Mini Greenhouse provides 1.67- x 3.25-ft. of growing space, and the curved roof lets light in from every angle. A handle makes this small cold frame easy to move.
It features a black galvanized steel frame and UV-resistant clear plastic cover, with adjustable air vents on each end. Ideal for kitchen growing, this fits as well on a porch or patio as it does in the garden.
via merchant
Best Handmade Cold Frame
Cedar Cold Frame Garden
Another wooden cold frame, the Cedar Cold Frame Garden from Home Garden LLC features long-lasting, well-insulating cedar frame, a double-walled polycarbonate lid and 2- x 4-ft. of growing space.
Heavier than most, this will probably stay in one spot, but it’s attractive enough to be a centerpiece wherever you put it. And did we mention it’s handmade? It comes in sections easily assembled with a screwdriver, thanks to the easy-to-follow instructions.
What to Consider When Buying Cold Frame Greenhouses
- Size: Cold frames are built with little headroom to maximize warming, but footprints vary. Anything less than 4- x 8-ft. is considered portable. Larger cold frames are best left in one place.
- Lids: Hinged lids allow access to what’s inside. Some cold frames have more than one lid so you can reach some plants or germinating seeds without disturbing others.
- Frame material: Common greenhouse materials include glass, wood, polycarbonate, fiberglass and aluminum. Wood, the heaviest and best-insulating material, is most suited for a stationary installation. Aluminum is generally the priciest and longest-lasting. Some frames feature an aluminum structure supporting polycarbonate or glass panels.
- Lid material: Because the lid must be transparent, these are usually glass and polycarbonate. Glass weighs more and it’s stronger, so it’s better for windy conditions.
- Ventilation: Most cold frames feature hinged lids that can be adjusted or removed. If the lid can’t come off, there should be vents on the sides.
Why You Should Trust Us
With more than four decades of experience in the building trades, I have a wealth of hands-on expertise. As the co-owner of a California property independent of the electric grid, I have a deep understanding of solar power and its applications. This makes me well-versed in the specific needs and benefits of cold frame greenhouses. I’ve also contributed to major construction projects and co-established landscaping companies. In addition, I’ve worked extensively as a carpenter, landscape builder and furniture refinisher.
Since turning my focus to writing, I’ve published and consulted on more than 10,000 articles for Family Handyman, Hunker.com and more. I’ve also served as an online building consultant for Home Depot’s Pro Referral service, further establishing me as a trusted source for reliable home improvement advice.
How We Found the Best Cold Frame Greenhouses
When selecting the best cold frame greenhouses, we researched a wide range of options to understand the features and benefits offered by different models. Next, we analyzed customer reviews to gain insights into real-world experiences with these products. Our evaluation focused on factors such as durability, insulation, size, affordability and ease of assembly. We also looked at the effectiveness of extending the growing season. The result is a curated list of the best cold frame greenhouses to suit every space and budget.
FAQ
What is the purpose of a cold frame greenhouse?
A cold frame greenhouse is designed to extend the growing season by providing a protected environment for plants. It helps to retain heat from the sun, which creates a microclimate that is warmer than the surrounding outdoor temperatures. This allows gardeners to start planting earlier in the spring and continue growing later into the fall.
Does a cold frame need to be in the sun?
Ideally, you should place a cold frame greenhouse in a sunny location to maximize its effectiveness. The sunlight helps to heat up the interior of the cold frame, which creates a more favorable environment for plant growth.
Originally Published: July 26, 2022
