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What is a Cold Frame Greenhouse? And Everything Else You Need to Know

cold frame greenhouses

When buying a greenhouse, one of the most important questions you need to ask yourself is whether you want a cold frame greenhouse or a traditional greenhouse. Unfortunately, this is not an easy question to answer, especially when it's hard to determine what a cold frame greenhouse actually is.

Don't worry. We've got you covered.

In this post, we will go over what a cold frame greenhouse is and everything else you need to know about cold frame greenhouses before you buy one. 

What Is a Cold Frame Greenhouse?

A cold frame greenhouse is a structure that is designed to protect plants and extend their growing season. Cold frame greenhouses don’t use any external heat or ventilation sources, such as electric heaters, gas heaters, or fans, like traditional greenhouses. 

Most cold frame greenhouses are smaller structures compared to traditional greenhouses. But, cold frame greenhouses can be larger structures as well. Often, cold greenhouses are used by commercial growers.

 

When To Use A Cold Frame Greenhouse?

It’s not always clear when you should use a cold frame greenhouse over a greenhouse. Below are some instances when a cold frame might be better than a traditional greenhouse. 

 

1. Extend your growing seasons

Cold frame greenhouses are a great way to extend your growing season. This is especially true if your region experiences moderate weather conditions such as light rain or snow. Oftentimes, moderate weather will cause gardeners to harvest their vegetables sooner than they would like. With a cold frame greenhouse, they can continue growing even when the weather is not ideal.

 

2. Protect your plants from harsh weather

If you have full-grown tropical plants or vegetables cold frame greenhouses are a great way to protect your plants. Cold frame greenhouses can protect your plants from harsh weather conditions such as rain or snow with the covered walls and roof.

In addition, if the weather gets too cold, a cold frame greenhouse can provide insulation. The insulation will prevent the outside temperatures from reaching your plants. In addition, the insulation also helps trap any heat during the day to prevent your plants from getting too cold at night. 

They are able to provide protection when the conditions are not ideal while still allowing your plants to take advantage of any light or heat when it is available by using a clear cover. 

The cold is not the only danger to many plants. Extreme heat can also cause extreme damage to your plants. Cold frame greenhouses are a great way to protect your plants from the heat as well. You can use a cover that is opaque, reducing the light and heat that reaches your plants. In addition, if your cold frame greenhouse already has a clear cover, you can use shade covers to reduce the amount of heat and light that reach your plants. 

 

3. Start Seedlings Earlier 

Another common use for cold frame greenhouses is to start growing your seedlings earlier. This means that growers can start several weeks or months earlier than they usually wood. 

Rather than waiting for the temperature to reach the ideal temperature. You can use your cold frame greenhouse to create the ideal environment earlier than it would. 

For example, you can start seedlings as winter ends rather than waiting until the temperature starts to warm up. On the other hand, you can also start growing seedlings as summer or autumn ends rather than waiting for a complete change in seasons or weather. 

 

4. Overwintering of Plants 

Cold frame greenhouses offer an easy way to protect your plants so that they can overwinter your plants. Some plants require overwintering to experience a proper growing season. 

On the other hand, some growers use cold frames as a way to overwinter their plants and help them survive cold temperatures. 

In either situation, cold frame greenhouses are great for overwintering because they are inexpensive and versatile. They are easy to move, come in a variety of sizes, can either be purchased or made yourself depending on your needs and are also moved easily. 

 

5. Hardening off your seedlings 

Hardening is required for a proper transition of your seedlings. The process involves getting your seedlings accustomed to the outdoor or new environment that they will be growing as they mature. 

Without a cold frame, this process includes leaving your plants outside for short periods of time over a week or longer. With a cold frame, the process is much easier. 

A cold frame greenhouse will allow you to easily harden your seedlings. You can do this by storing them in a cold frame greenhouse. With the lid on, they are protected and are not being hardened. When you remove or lift the lid, you begin to harden your seedlings. 

You can repeat this process over a week or two until your seedling is ready to experience its new growing conditions. With certain cold frame greenhouses, you can either transport the seedlings to their permanent growing location or simply remove the cold frame greenhouse and keep your seedlings in their current position. 

 

Advantages of a Cold Frame Greenhouse

The main advantages of cold frame greenhouses are that they are inexpensive and easy to build. You can make them out of a variety of materials or out of traditional materials as well. 

  • Inexpensive compared to traditional greenhouses 
  • Can be homemade or DIY kit 
  • Extends the growing season 
  • Protect plants from weather conditions 
  • Easy to move and reposition if necessary
  • Doesn’t require external heating sources 
  • Usually smaller or lower to the ground for easy growing. 
  • Easy to adjust the size to meet your growing needs
  • Low maintenance and easy to repair

 

Disadvantages of Cold Frame Greenhouses

Cold frame greenhouses don’t come without their disadvantages. The key disadvantage of cold frame greenhouses is that they can’t handle the same harsh conditions that traditional greenhouses can. In addition, traditional greenhouses offer greater control over the conditions inside the greenhouse. 

  • Smaller than traditional greenhouses 
  • Limits growing space, can’t grow larger plants
  • Can’t withstand harsh weather conditions 
  •  Difficult to regulate temperature
  • Low to the ground requires lots of bending down and crouching.

 

How do you keep cold frame greenhouses warm at night? 

There are a few different options you can use to keep your cold frame greenhouse warm. 

  1. Use additional insulation to maintain any heat it absorbs during the day 
  2. Make sure your cold frame is properly sealed to trap heat inside and keep cold out
  3. Use manure - since manure releases heat as it decomposes 
  4. Place items around the outside of your greenhouse to keep it warm 
  5. Make your cold frame greenhouse a hotbed by adding an insulated heating cable 
  6. Place your cold frame in a position that maximizes the amount of sun it receives
  7. Use a clear lid and other heat-absorbing materials to trap as much heat as possible during the day

Since cold frames don’t use any electrical or other external sources of heat - you will need to think of ways to trap or absorb heat as much as possible. 

 

Types of Cold Frame Greenhouses

There is a common misconception that cold frame greenhouses are small structures that are close to the ground. This is not the case, a cold frame greenhouse can take and size and shape. 

 

1. Raised Garden Bed Cold Frame Greenhouse 

Raised garden bed cold frame greenhouses are one of the most common types of cold frame greenhouses. These greenhouses are simple; they are raised garden beds with some type of cover over them. The covers can either be flat lids, A-frame lids, or any other type of lid with some type of clear, insulated cover. 

 

2. Elevated Planter Cold Frame Greenhouses

These are your common planters that are typically handing or elevated with some kind of base. In these cases, the elevated planters have an insulating, clear cover that allows sunlight inside but also protects the plants from the elements on the outside. 

 

3. Shade House Cold Frame Greenhouses 

A common misconception is that cold frame greenhouses are small structures that are close to the ground. This is not the case, cold frame greenhouses can be large structures. These types of structures are commonly used by commercial growers. 

These structures are referred to as shade houses since they don’t have end walls and only have top and sidewalls. These structures are also considered cold frame greenhouses. 

Shade houses are also cold-frame greenhouses. They can take several shapes, including a tunnel, A-frame, gables, or gothic frame. 

  • Gothic Frame Cold Frame Greenhouse
  • Tunnel  Cold Frame Greenhouse
  • A-Frame Cold Frame Greenhouse
  • Gothic Arc Cold Frame Greenhouse

 

4. Row Cover Cold Frame Greenhouses

Row cover cold frame greenhouses are short covers that cover rows of plants. These row covers are typically short and low to the ground. These are ideal for growing short plants, growing seedlings, or bush-style plants. 

Row cover cold frame greenhouses are around between two feet and five feet tall and two to three feet wide. Therefore, these cold frame greenhouses are often thought of as shorter and smaller tunnel cold frame greenhouses. 

 

5. Shelf Cold Frame Greenhouse

These cold frame greenhouses are designed as a shelf, with clear glass doors in front as well as the top that allow light to enter through. This allows your plants to get sufficient sunlight while protecting them from harsh weather conditions. 

The benefit of shelf cold frame greenhouses is that you don’t have to bend down frequently. The shelf style makes it easy to access your plants, but it does require separate planters to store all your plants properly. 

 

What can you grow in a cold frame greenhouse during winter? 

You can grow plants in all four seasons of the year, not only in the cold or hot months of the year. Cold frame greenhouses are a great way to ensure you can provide protection when necessary. 

Below are some plants and vegetables that perform well in a cold frame greenhouse in particular during winter.

  • Carrots
  • Leeks
  • Radishes
  • Salad greens 
  • Arugula
  • Spinach
  • Mache
  • Lettuce
  • Beets 
  • Radish
  • Turnips 
  • Kale 
  • Mustard 
  • Green Onion 
  • Chard 
  • Broccoli

 

Is a cold frame as good as a greenhouse? 

Yes, a cold frame greenhouse can be as good as a greenhouse. Cold frame greenhouses are ideal for areas that don’t experience extreme weather conditions. 

Cold frame greenhouses are less expensive, easier to maintain, and easier to build than traditional greenhouses. 

It's important to remember that cold frame greenhouses don’t use any source of heat or ventilation as a greenhouse would. This does not mean that they don’t come with some clear disadvantages.

 

Is a cold frame greenhouse worth it?

Yes, cold frame greenhouses are worth it. One of the main reasons they are worth it is that they provide key benefits for your plants such as extending your growing season, protecting your plants from harsh weather conditions, allowing for earlier growing seasons, and providing ideal growing conditions for seedlings. 

One of the major advantages of a cold frame greenhouse is that they are easier to build, requires fewer materials, and is less expensive than traditional greenhouses. 

 

Can you start seeds in a cold frame? 

Yes, you can start seeds in a cold frame greenhouse. You can also use cold frame greenhouses to harden your seedlings. 

Cold frame greenhouses are a great way to protect your seeds from the weather conditions outdoors. In addition, it allows you to create an ideal growing environment that otherwise wouldn’t be available outdoors. 

The benefit is that these cold frame greenhouses are typically smaller and shorter, making it easier to control and create an ideal environment. This makes them easier to build, insulate, and cool. 

 

Conclusion 

After reading this article, you should know everything you need to know about cold frame greenhouses if you were confused about cold frame greenhouses.

Now that you have a clear idea of what cold frame greenhouses offer as well as their advantages and disadvantages you can decide if a cold frame greenhouse is right for you. If you are in the market for a cold frame greenhouse, we provided a list of the best cold frame greenhouses on the market that you can use as a buying guide.