When you grow plants not hardy to your particular zone or microclimate, you need to have more control over the temperature, humidity, and ventilation along with several other growing conditions.
A greenhouse gives you that control and allows you to grow tropical plants in cold zones. A polytunnel also serves the same purpose. So which one should you use?
Is a polytunnel as good as a greenhouse? In terms of climate control and ventilation, a polytunnel has the same qualities as a greenhouse. However, a polytunnel is easier to install, and it provides better ventilation for the plants. In terms of heat retention and light transmission, a greenhouse is a better option than a polytunnel.
If you’re still undecided between the greenhouse and the polytunnel, read more to find out which one is better for your specific purposes.
Polytunnel or Greenhouse – How To Decide
There are a lot of factors that help you decide whether to go for a greenhouse or install a polytunnel for your plants.
Some of these factors include ventilation, heat retention, shading, durability, and other design considerations.
While greenhouses are typically made of glass and sit on a foundation, polytunnels use a simple frame covered with plastic and can be set up directly on the ground.
Because of their design and ability to transmit light, greenhouses are better suited for growing flowers, exotic plants, and other tropical plants that need specific growing conditions.
A polytunnel, on the other hand, is more suitable for growing large crops, fruits, and vegetables.
A polytunnel, like this one, is easy to install and can be set up and ready to use in a single day. However, you need to find a spot sheltered from strong winds to protect the polytunnel.
A greenhouse is a more elaborate structure that takes a lot of work to get everything installed.
On average a polytunnel would cost around $3,500. However, you could find smaller and cheaper polytunnels. A greenhouse is more costly.
If you build the greenhouse yourself, it could cost a little over $7,000 for the materials. A ready-made greenhouse sells by the square foot and costs between $25 to $35 per square foot.
Heat Retention / Climate Control
Both the polytunnel and a greenhouse do a good job controlling the climate and providing the right temperature and humidity levels for the plants.
However, polytunnels have a problem with condensation and need thermal anti-fog covers to solve this problem.
A greenhouse is better with heat retention, and it allows more light inside than the polytunnel.
Both the greenhouse and polytunnel can last for many years, but a greenhouse is more durable and can last for a lifetime.
Keep in mind that the plastic covering of a polytunnel will degrade over time, especially under direct sunlight.
Replacing the cover will need to be done every 4-5 years or so, and it can be a big job depending on the size of the structure.
They both have the same functionality, but a greenhouse is more designed for planting flowers and exotic plants.
A polytunnel is a more cost-effective option for growing large crops of veggies and fruits.
Maintenance & Repairs
A greenhouse is a more complex structure than a polytunnel. This reflects on the maintenance and repair work required to keep each structure in good shape.
You’ll spend more time maintaining your greenhouse than you would with a polytunnel.
Common Questions About Polytunnels
Are Polytunnels Warmer Than Greenhouses?
A polytunnel covered with thermal polythene is warmer than a greenhouse with all the ventilation drafts.
In a way, a polytunnel is more protected against the elements and provides warmer temperatures during the winter.
Disadvantages of Polytunnels
Condensation is a major problem with polytunnels. The plastic is flimsy and requires replacement every 4-5 years on average, which can add to the overall cost and maintenance work.
How Long Do Polytunnels Last?
Polytunnels can last for several years before needing new covers. However, the frame itself can last for decades if well cared for.
What’s the Best Plastic for Polytunnels?
The best plastic for polytunnels is standard light-diffusing polythene. It allows as much as 89% of the daylight inside.
How Do You Shade a Polytunnel?
You can keep the inside of the polytunnel cool with a shade net. Install the net on the roof of the tunnel from the inside.
Can You Heat a Polytunnel?
You can heat the polytunnel. However, this is a costly process considering the large area inside of the tunnel and the flimsy plastic walls, which are not great at retaining heat, especially when it’s freezing outside.
Whether you want to install a polytunnel or a greenhouse, factors like cost, type of crops you will grow, and durability should help you make your decision.
A polytunnel is easy to install in one day, and it costs less than a greenhouse. It’s more suited for large crops of veggies and fruits, but it can have issues with condensation and light transmission.