Glass cloche or plastic cloche? Which are the best garden cloches for your organic garden?
There’s no doubt that a good cloche can help your plants to grow effectively and without interruption from birds or other pests. The air temperature is raised and young plants are protected from sudden frosts, heavy rain and wind.
You can also warm the soil early by setting out garden cloches. This means that crops can be started sooner than would otherwise be possible.
The glass cloche has been with us for a good long time. - since Victorian times, at least. Now there’s a wide selection of plastic and other materials to choose from. So which are the best garden cloches for green living? Which offer the best value for money and which are the most durable?
Here’s a look at some of the best cloche materials, from glass to acrylic and fleece. Cloches are also known as row covers - we'll use the terms interchangeably.
A glass cloche should last for years if you store it carefully. It will be impervious to most weather conditions. Snow will just build up on it and will be unlikely to cause any damage unless conditions are really extreme. Frost and temperature changes should be no problem. But even a sturdy glass cloche will not stop the lowest temperatures from doing some damage to tender plants.
But glass is heavy and relatively expensive. There is also the risk of breakage and the danger to other garden users such as children.
Most glass cloches are supplied with horticultural glass, which is made to a lower standard than glass for domestic use. It has more imperfections and is more prone to breakage. When it breaks it may shatter into large, extremely sharp shards. The main advantage of horticultural glass that it is cheaper than standard glass.
If you do decide to buy glass garden cloches, look for toughened glass as standard so that you don’t need to worry so much about accidents. Toughened glass is also easier to keep clean because of the lack of imperfections in the surface of the glass.
Victorian bell jars have become popular but they are of limited use if you want to grow a lot of crops. They tend to protect one or two plants at best. This is a relatively expensive way to care for your plants. The main advantages are that they look quite nice and they can easily be moved about.
Victorian times supply another inspiration; cast iron cloches with glass windows. They are sometimes called lantern cloches. These are heavy and relatively expensive but will do a good job as they are impervious to practically any normal weather. They are heavy enough to not blow away or cave in and the plants will remain snug at all times. The best ones are zinc coated to stop any possibility of rust forming. They are easy to use and can be moved about as required.
Poly(methyl methacrylate) (PMMA) is usually known as acrylic glass. It makes a good, light weight cloche but the two main disadvantages are that it scratches quite easily and can break if it suffers a direct impact. It‘s also known under trade names such as Plexiglass and Perspex.
Acrylic glass is not a real type of glass at all but a polymer that has wide uses in industry and modern life. Everything from shoes and dentures to fighter jets may contain this remarkable material. It’s yet another product which has its origins in petrochemicals.
Polymers vary in their life-span and capacity for degradation by light and heat. Look for the best quality to avoid problems with products with short life-spans. Many products made of polymers can be recycled, including acrylic glass made of PMMA.
Acrylic glass is relatively good at resisting impact and it has good light transmission, so it makes a good garden cloche material.
Most of these cloches are made from polyethylene and so are relatively cheap.
The main problem with using polyethylene is that it degrades in sunlight but not sufficiently to be biodegradable. Most of it deteriorates within a few years of use – and ends up in landfill. Look for ones using UV stabilised plastic for a slightly longer lifespan.
Polyester is also used for flexible garden cloches and this is rather better with regard to recyclability. It can be broken down and pelleted to make new plastic products – rather than just ending up as yet more landfill. Look for the PET symbol on the product description.
With a little care you may get several seasons use from your plastic cloche – but you are unlikely to be passing on your plastic garden cloches to your kids!
Plastic cloches are often in the form of mini-polytunnels with wire hoops to support the plastic. The ends can be tied or weighted to stop birds and other hungry beasties from getting into the growing area.
You can easily make homemade plastic cloches using scrap materials. Plastic cloches offer a cheap, flexible solution but do not expect durability. It’s probably better to buy either horticultural fleece or rigid polycarbonate row covers if you want a fairly cheap but durable option.
PVC cloches are also available and they tend to be quite durable and yet lighter than traditional glass. They are resistant to damage from sunlight so they will usually last a good few years. Most of the sunlight passes through them (about 85%) so they are quite effective for strong plant growth. Larger ones are sometimes available made from corrugated PVC. These are suitable for growing larger plants such as beans or courgettes.
Many PVC cloches are sold as long tunnel-like designs. Be aware that cloche designs featuring some form of ventilation are the best; plants will quickly die from overheating in hot sunlight. Many have panels that can be removed from the ends.
Floating cloches are increasingly popular. Horticultural fleece is simply cast over the plants and weighted down with stones or bricks to stop lift off in windy weather. Fleece is permeable to water and light so you do not need to remove it in order to water the plants.
Some firms now sell fleece supported by wire hoops. This seems like a good idea in theory – but in practice the fleece is likely to tear and snag on the wire.
Picture: Caveat emptor - buyer beware: A very biodegradable mini-polytunnel!
It is better to use plastic plumbers tubing and sheets of quality horticultural fleece to get the same effect in a more durable and cost-effective way. The quality of fleece used makes quite a difference.
See the picture, right, for the results of using cheap fleece with wire hoops. This product lasted for only a few short weeks before sunlight and weather degraded it to this extent.
Bamboo can be a good material for cloches as it is light yet flexible and creates shade without excluding light. If keeping wild birds and insects off your crop is your main concern these might be helpful. They also cut down the worst effects of strong winds and offer some protection against light frosts.
Bamboo is a relatively sustainable product as it grows quickly with few inputs.
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