Will a Plastic Greenhouse Protect Plants From Frost?

Plastic greenhouses offer many benefits in the winter and are cheaper to start than costly glass greenhouses. However, if your plant’s longevity is at the forefront of your mind, you might well ask: Will a plastic greenhouse protect your plants from the winter’s cold? 

A plastic greenhouse will protect plants from frost. Typically a plastic greenhouse can maintain a temperature a few degrees higher than the outside temperature. Though not as effective as glass, plastic is better than leaving plants exposed to the cold and offers insulation.

If your budget is tight, there is no reason why you can’t use plastic to protect your plants in winter. In the rest of this article, I will discuss plastic greenhouses’ effectiveness, pros and cons, and how to keep your greenhouse warmer in the winter. So if you want to learn more about plastic greenhouses and the best way to use them when it’s cold, let’s get started.  

Is a Plastic Greenhouse Effective at Protecting Plants From Frost?

Indeed, plastic greenhouses are not as effective as the typical glass ones. However, plastic greenhouse designs are only getting better as time goes on. Plus, having some sort of protection for your plants from the cold air is always a good idea. 

A plastic greenhouse is effective at protecting plants from frost to a certain degree and is much better than leaving your plants exposed to icy conditions. However, there are many ways to improve your plastic greenhouse insulation and even plastic-friendly heating options. 

It’s also important to note that people use a wide variety of plastic for greenhouses, and not all plastics are created equal. For example, some plastics do a far better job of insulating, while others tend to take on whatever temperature is outdoors. 

Pros of Using a Plastic Greenhouse

Plastic greenhouses can be an excellent way to house and keep your plants warm if you know what to do. But, as with any product, there will be benefits and drawbacks to using it. So I will first talk about some pros of using a plastic greenhouse to house your plants. 

Plastic greenhouse pros:

  • Increases inside temperature by 4-5 degrees: Lighter plastic greenhouses can slightly increase the temperature inside their house, providing your plants much-needed warmth. Just monitor the temperature at night as it can easily fall when it gets too cold. 
  • Cost-effective: Plastic greenhouses come in various models to suit your particular needs. Plus, they are pretty cheap to purchase and maintain. A plastic greenhouse is an excellent option for a gardening beginner looking not to spend too much. 
  • Relocatable: Plastic greenhouses are light and meant to be portable. You can change the location of your greenhouse until you find a spot that works perfectly for your plant’s needs. 
  • Easy Assembly: Plastic greenhouses tend to be far simpler to put together and can easily be set up and taken down whenever needed. 
  • Light filtering: The plastic in the greenhouse can do a great job filtering harsh rays that may scorch your plants during the hotter months. 

So as you can see, plastic greenhouses work, and there are quite a few benefits to using one. Those living in warmer, more tropical environments often opt to use a plastic greenhouse as it fits their needs perfectly. 

Cons of Using a Plastic Greenhouse

Now that you understand the benefits of this type of greenhouse, it’s time to talk about the downsides of using a plastic greenhouse. They are indeed a great invention, but there are several drawbacks you should consider before investing in one. 

Plastic greenhouse cons:

  • Susceptible to high winds: Because plastic greenhouses are so lightweight, they are far more likely to blow away or be knocked over in a windstorm. However, you can certainly take steps to prevent this, like bringing your greenhouse inside when it’s windy or weighing it down. 
  • Not biodegradable: Since this type of greenhouse is plastic, it will never decompose, so it’ll sit in a landfill if you decide to get rid of it. However, you can certainly try to have it recycled. 
  • Wears down: Sadly, plastic will have a shorter lifespan than a typical glass greenhouse. Plastic is highly susceptible to extreme temperatures and, over time, will begin to break and wear down. 
  • Becomes sun warped: Plastic is susceptible to UV light and will eventually melt or break apart under the sun’s harsh glare. You can combat this by providing shade, but it will ultimately happen if you live somewhere with constant intense sun. 
  • Difficulty maintaining temperatures: Plastic greenhouses can get quite hot during the summer, scorching your plants. While in the winter, the opposite happens, and your plants might freeze. 

So there are about as many drawbacks as there are benefits to using a plastic greenhouse, and honestly, everyone’s gardening needs will be different, so if a plastic greenhouse works best for you, that is great. 

Not to mention that you can address many of these disadvantages with some work. Plus, a greenhouse is always better for growing your plants than outside in direct sunlight.

How To Combat Cold Temperatures in a Plastic Greenhouse

So now that you know some of the pros and cons of using plastic greenhouses, it’s time to talk about how you can improve their ability to function in cold weather. As with any design, you can continuously improve your plastic greenhouse. 

Ways to insulate your plastic greenhouse for the winter:

  • Sheets of bubble wrap: Bubble wrap can help trap in the heat during the wintertime. Simply take some bubble wrap sheets and secure them outside your structure. 
  • Wool blankets: Heavy or wool blankets can be fastened outside your greenhouse to help trap the heat at night. 
  • Plastic bottles: Placing cut-off plastic bottles over every plant in your greenhouse can be an excellent way to ensure each plant has its own added protection during the cold months. 
  • Use compost: Compost can act as a heater, and by placing some hot compost into your plastic greenhouse, your structure will be better able to maintain its temperature throughout the winter.
  • A heater: You can use a heater in a plastic greenhouse if the structure is large enough and you are EXTREMELY careful. Using a heater in a plastic greenhouse can be a fire hazard, so you only want to run the device sparingly. 
  • Large rocks: Placing large rocks at the bottom of your greenhouse to collect heat throughout the day can help maintain the greenhouse’s temperature during chilly nights. 
  • Bring your greenhouse inside: If your greenhouse is small and portable, you should consider wheeling it inside when the temperature drops at night. This action will help your plants stay warm and away from harmful frost. 

You can take several steps to ensure that your plastic greenhouse maintains its heat and that your plants don’t become frostbitten. Plastic greenhouses exist for a reason; they do work. You will simply have to pay more attention to the weather and take steps to insulate when it’s cold. 

Frequently Asked Questions 

Should I Open My Plastic Greenhouse During the Day?

You should open your plastic greenhouse during the day if the temperature inside of the greenhouse is too hot for your plants. In contrast, you may want to keep the door closed to trap the day’s heat for cold winter nights. 

What Type of Plastic Is Best for Greenhouses?

The best type of plastic for greenhouses is polyethylene plastic. This plastic type holds up better under the sun’s harsh rays and does a better job insulating your greenhouse, especially during the cold winter. 


Ultimately, plastic greenhouses can do a great job protecting your plants from frost. However, depending on the plastic used, you may need to install additional insulation to keep your plants safe during harsh winters. So depending on your specific gardening needs, a plastic greenhouse might be perfect for you.

Alexander Picot

Alexander Picot is the principal creator of TheGrowingLeaf.com, a website dedicated to gardening tips. Inspired by his mother’s love of gardening, Alex has a passion for taking care of plants and turning backyards into feel-good places and loves to share his experience with the rest of the world.

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