Gardening Tips: Choosing and using cloches
Cloches are one of the most important forms of plant protection. Used sensibly, and with good forward planning, cloches can help you to grow a number of crops with less effort, and to produce crops much earlier in the season. It is true that for some gardening jobs, such as the raising of young brassicas from seed, there is little to choose between a cloche or a frame, and for certain crops, like cucumber or, frames may have the advantage of extra width and height. Nevertheless, for the home grower cloches have a number of advantages which make them an attractive proposition: mobility, ease of watering and ventilation, the extra light that penetrates through the sides, and the lower cost per area covered compared with a frame.
Making the most of cloches
Cloches are excellent not only for raisingand hardening off plants, but also for growing many crops to maturity. The period of growth from sowing or planting to harvesting can be considerably shortened by the use of this form of protection. Used early in the season, cloches can give a crop like runner beans an early start, or they can effectively protect autumn crops like , tomatoes and strawberries.
It is possible to use one set of, say, three cloches or more on as many as four or five crops in a year, and intercropping—growing two crops together like lettuce and radish—could increase this number even more. For instance, two crops of spring lettuce, followed by, late summer or autumn-sown , then a late lettuce crop or is a practical proposition. The most efficient use of land and cover can be obtained by growing the succeeding crop immediately alongside the plants being protected. In this way a following crop like autumn lettuce can receive some from the wind. And when the cloches are removed they are transported the minimum of distance, saving time and effort and with less risk of damage. The crop you have uncovered will still receive some protection from wind from the cloches nearby. This system of growing rows of similar width alongside each other is often known as strip-cropping.
Principles of cloche gardening Your degree of success with cloche gardening will depend not only on your own efforts but also on a number of outside factors. The effect of a cloche is to create inside itself a milder climate compared with unprotected land, so climate is a key point. For example, gardeners in northern England and Scotland, with good cultivation, could expect to grow four crops a year under a set of cloches, whereas in southern and western parts of England and Wales it is possible to improve on five crops a year without difficulty. Early cropping is also affected by thetype, clay being slower to warm up in spring than sandy soils. With all soil types, however, cloches have a beneficial effect, even after quite brief periods. The soil is easier to work, being drier than wet, rain-sodden, unprotected land.
The temperature rises quite quickly under cloches placed in a sunny spot. Thus, both the plants and the soil beneath the cloches warm up quicker than the soil outside. At night, soil and air under cloches are also warmer due to lower heat loss. Therefore, by protecting crops from wind, rain, frost and snow, plant growth rates are accelerated.
Unfortunately, however, the warmer conditions, which favour more rapid growth and earlier crop development, may also encourage the build-up of pests, or diseases such as mildew and botrytis. Thus watering, feeding, and pest and disease control will require closer attention with cloche-grown crops than with unprotected crops outside, especially during spring and autumn.
Types of cloche
Modern cloches are predominantly of the continuous type, so called because they form an uninterrupted tunnel, unlike the old-fashioned ‘lantern’ or bell-shaped models. Materials used are either glass, or rigid or flexible plastics, with some means of metal or wood support and anchorage. The rigid models of cloche, constructed from fiat sheets, are generally more easily ventilated and have drier internal conditions, with less condensation on the skin, than the flexible types. Cloches constructed of glass tend to be heavier than rigid plastic, and break more easily, but are an odd degree or two warmer during both day and night. Regardless of type, cloches can give considerable protection from wind, provided the ends are sealed and they are placed close together without leaving wide gaps.
The cloche tunnel: various versions of this can either be bought or made at home, consisting of wire hoops pushed into the ground and covered with polythene sheeting anchored by soil, stones or bricks. The dimensions vary considerably, but 45 cm and 60 cm (18” and 24” widths are common. Such sheeting has to be handled carefully as it is very easily torn at the edges, especially where it is caught in between the wire hoops. It is also important to anchor it securely, so that the wind cannot get underneath and blow it up, or tear it. When erecting tunnels, do not put the wire hoops more than about 75 cm (2-½) apart, otherwise the sheeting tends to sag down onto the crops. Double skinned: a double layer of polythene, over a galvanized or plastic covered frame, is an inexpensive form of cover, but the method of anchorage needs to be effective. The shapes currently available include tent, barn and inverted ‘U’. One available form of galvanized section measures 75 cm long x 30 cm (12”) high x 30 cm (12”) wide, providing good growing conditions under a complete tunnel length. All types of continuous cloches, whether of the rigid or flexible variety, must have the ends closed to keep warm air in, and the wind and the birds out.
Siting the cloches
Select a sunny spot for the cloche garden, and keep the cloches together in units. Prepare the soil as well as you can; it should be well-drained and fertile, but capable of retaining moisture in summer. Low-lying land which is inclined to be waterlogged in winter can be improved in many cases by growing cloche crops on.
Manuring and feeding needs to be generous, particularly for crops that are gross feeders, such as celery and tomatoes. To get off to an early start, it is a good idea to place cloches over the ground to be used a week or two before you need to prepare it. This will warm up and dry out the soil, so that you can work the land easily at an earlier date than usual— otherwise it might have been too wet, or frosted. In districts which have a heavy rainfall, a 5 cm (2”) layer of ash cinders laid as a permanent path beside cloches will make walking and working easier and cleaner. In exposed and cold regions you may need to provide extra protection from freezing winds. In the short term, chestnut paling, fastened securely to posts no more than 1.8 m (6’) apart, will provide a useful temporary wind break. A thorn hedge or some more permanent protection is a good idea if you plan to go in for regular early and late cropping in colder areas. Whatever the type of windbreak, it must not overshadow the cloches, or more harm than good will be done. Cloches should be placed some distance away from hedgerows, as the roots from the hedgerow shrubs tend to rob the soil of nutrients. As a general guide, windbreaks are effective over a distance ten times their height, so your cloches will still get some protection from wind when sited up to 10 m (30’) away from a 1 m (3’) high hedge.
When the soil is finally prepared to receive plants and cloches, it is important to make it as level as possible—a level finish will ensure good contact between ground and cloche and prevent draughts.
Lightweight plastic cloches can be blown about, with both crops and cover being damaged, unless some effective means of securing them is used. Wire hoops can be very effective when inserted into the soil. Make sure you secure the end coverings. Hold a sheet of glass or plastic in place by canes at each end of a row.