Cloche: A low portable unit constructed of glass or rigid-plastic panes on a wire frame; used for the protection of plants, advancement of growth and warming of the soil. A polythene film stretched over wire hoops is known as ‘a low continuous polythene tunnel cloche.
Earthing-up: The drawing up of soil around plants, usually with a draw hoe or drag fork. It is carried out on potato crops to prevent greening of tubers and blight infection; also used on brassicas to prevent wind-rock, on leeks and celery to blanch the stems, and in layering and stooling of fruit-tree rootstocks, to encourage the formation of roots on the earthed-up shoots.
Forcing: The acceleration of a plant’s vegetative growth, flowering or fruiting, using the manipulation of temperature and light to ‘force’ the production of the growth desired. Rhubarb, chicory and hyacinths are commonly forced. Commercial forcing is carried out in specially designed greenhouses or sheds, often with additional bottom heat. In the domestic garden forcing is usually improvised in greenhouses and frames, or achieved with the use of forcing pots to cover individual plants.
Soil improver or soil conditioner: Any substance dug in to improve soil structure. This is generally organic matter, such as animal manure, garden compost, or leafmould, but could be an inert substance such as lime or gypsum. Synthetic soil stabilisers (e.g. polyvinyl alcohol, cellulose acetate, and polyacrylamide) are used commercially to prevent soil capping (formation of a surface crust on the soil when drying after heavy rain).