POLYTUNNEL AND GREENHOUSE COMPARISON IN THE UK
Before buying a polytunnel or a greenhouse it's worthwhile comparing the two options. Much of what is described below may seem to be just common sense but drawing together all the plus and minus points in one document can often be useful.
We have significant experience of growing plants in both, the ideal solution, if money and space allow, is a greenhouse and a polytunnel! Read on though to come to a conclusion as to which is best for you.
This comparison section covers the following:
- COSTS OF BUYING
As far as costs are concerned polytunnels are, by a long way, the cheapest option and this is especially the case the larger the area covered. A basic, cheap as chips 2.5m x 2m (approx 8ft x 6ft) polytunnel can be yours for as little at £50 delivered to your door. We are not recommending them at this price but they do satisfy the needs of some gardeners on a budget. The cheapest greenhouse of that size will cost you well over £200.
- EASE OF CONSTRUCTION
The polytunnel wins hands down in this area as well. Two people and a day are normally more than enough to erect a basic polytunnel. A greenhouse will take far longer to build and is far more complicated although not beyond the abilities of two amateur gardeners. Expect to take at least two days to build a greenhouse, significantly longer if the site is not basically flat.
If diy capabilities are a concern we can recommend the Northern Polytunnels easy build range. Very strong polytunnels can be built using this system very easily. Click here for our news item on this range of polytunnels which explains it all in more detail.
- SITE PREPARATION
Be prepared for significant work preparing the site for a greenhouse, it needs to be on level and even ground. A polytunnel will benefit of course from ground preparation but they can be erected on some rather rough ground quite effectively. Also, the site can be on a slight slope.
- HEAT RETENTION
A greenhouse is definitely the best option if you want maximum heat retention. They will allow you to grow crops over a longer period of time and help them to successfully grow better if late or early frosts occur. Polytunnels do a good job of heat retention but not as well.
Greenhouses win on this comparison easily. Some of the timber framed ones can be considered almost as garden ornamentation but they are extremely costly.
Many greenhouses can last a lifetime if they are looked after well. A good quality polytunnel on the other hand might last 15 years in the same circumstances and the covering will need replacement after five years or so.
Growing plants under any form of cover in the UK runs the risk of the internal temperatures becoming too high which may damage plant growth. To get round this problem adequate ventilation is necessary. Opening doors is always an option with any structure and a door at either end to allow free air circulation is a good idea. Greenhouses can have thermostatically controlled opening panels whereas polytunnels (for amateurs) do not have this option although often the sides at the base can be opened for additional ventilation.
Greenhouses can get very hot and in most years the glass will need to painted to provide some shade. Polytunnels on the other hand are cooler because the polythene does the job of painting. Polythene also tends to diffuse light reasonably well whereas glass results in hot spots.
Greenhouses can be moved but it's a very time-consuming exercise and the risk of damaging panels is ever-present. Polytunnels on the other hand can be moved much more easily and the likelihood of damage is far less.
If you have kids (or a dog for that matter) and they use the garden then any structure made from glass is not really an option. Even if the kids don't get cut by the glass they will almost certainly end up breaking panels on an annoyingly regular basis.
- WATER COLLECTION
This is becoming increasingly more important and, on allotment with no water supply, an essential. Greenhouses can easily be adapted to collect water into a water butt, with polytunnels this is possible but more challenging.