Types of Garden Cloche
Types of cloches
Cloches are obtainable in a variety of sizes, shapes and materials.
Costs, naturally, are related to the size of the cloche, so it is prudent to decide what crops you intend growing under cloches before buying them.
If, for example, you plan to grow only early lettuces, a cloche 12in (305 mm) wide and 9in (230 mm) high is adequate. For growing melons to the fruiting stage, however, you will need cloches about 18in (455 mm) wide and 12in high.
Measure the row, then buy the required number of cloches to form unbroken protection over it. Remember to buy two end panels, as the cloche is not fully effective until these are placed in position.
Each type of material used for cloches has advantages and disadvantages.
Solid plastic cloches are cheaper than those made of glass but, initially, are dearer than polythene. They have a greater life expectancy than glass, which is easily broken, or polythene which must be replaced every few years.
Plastic cloches can be made of corrugated PVC, polypropylene, clear polystyrene or a number of proprietary materials.
Manufacturers have taken advantage of the flexibility and lightness of the plastic. Some cloches, for example, are 6 ft (1.8 m) long, a size that would be excessively heavy and cumbersome to handle in glass. Only three of these cloches are needed to cover a row 18 ft (5.5 m) long, so simplifying the task of moving them from crop to crop.
Widths of cloches vary from 7-½ in. (190 mm) for growing seedlings, to 2-½ ft (760 mm), in which two or three rows of vegetables can be grown to maturity.
Heights vary from 4in (100 mm), for seedlings, to 15in (380 mm), for fully grown plants such as bush tomatoes.
Solid Plastic Cloches
Solid plastic cloches are available with straight sides, or curved into hooped tunnels. Both designs are- equally effective, but some straight-sided models have the added refinement of ventilation flaps to reduce condensation and get air flowing. Condensation in solid plastic cloches is not, however, as serious as in polythene tunnels.
Polythene cloches are obtainable either as separate units, which are then put end to end, or as a complete tunnel cloche made from a length of polythene draped over wire hoops.
Polythene is obtainable in various gauges, or thicknesses. The thinnest, 150 gauge, is the cheapest form of cloche material but it will last only a year or two. Heavy-duty polythene, 500 gauge, is more expensive but it will last three or four years with reasonable care.
Polythene treated with an ultraviolet inhibitor to slow down deterioration is now available from horticultural suppliers. This lasts longer than untreated material.
Condensation is a problem with polythene. It can provide conditions for the spread of fungal diseases, so it is important to ventilate the cloches to clear the condensation and to get air circulating.
As polythene is light and unbreakable it has a big advantage over glass when being moved from one crop to another. Its lightness can be a disadvantage, however, in areas subject to high winds. If gales are forecast, anchor individual cloches with bricks, or form an inverted `V’ over them with canes driven into the ground. Tunnel cloches are satisfactorily anchored by their method of construction.
Glass cloches have proved their worth for many years, but the cost of glass and delivery have made them an expensive investment.
Many gardening centres now carry only a restricted stock, while firms that sell by mail order or on the internet, advertise only the wire supports and it is necessary to buy the glass from a local glazier. If you feel it is still worthwhile, order horticultural glass, which is cheaper than window glass.
Inevitable breakages also add to costs, but glass has some advantages over rigid plastic and polythene. When kept clean, glass cloches let in the maximum amount of light, and on cold, clear nights they retain heat better than polythene. Ventilation is good and on exposed, windy sites their weight makes them more secure than lighter materials.
There are three types of glass cloches — the tent, low barn and high barn.
A tent cloche consists of two sheets of glass about 24 x 12in (610 x 305 mm) fixed at the top by a galvanised-iron clip to form a pitched roof or tent.
Tent cloches are useful for raising seedlings or for single rows of crops such as lettuces, carrots and beetroots.
Barn cloches have four panes of glass, two forming sides’ and two the pitched roof. A low barn cloche is 2 ft (610 mm) long and 12in (305 mm) high. With a width of about 2 ft, it is possible to grow a central row of lettuces and outer rows of carrots or beetroot. The lettuces will be harvested first, leaving the other crops to mature.
A high barn cloche is as wide and long as a low barn but the height is about 19in (480 mm). A row of high barn cloches is useful for getting plants such as tomatoes, peppers and aubergines to a fairly advanced stage before protection is no longer necessary in high summer.