If your garden design includes a greenhouse then read on. Any garden, however small, can house a glass structure of some type and any greenhouse, however small, will add a new dimension to your garden.
All sorts of shapes and a wide range of sizes are available, but the fundamental difference between one type and another is the minimum temperature at which it is kept. The cold house is the simplest – no artificial means of heat are provided and so in the depths of winter the temperature can fall below freezing (33 deg. F). Despite this vulnerability to frost, the cold house extends the growing season by trapping the sun’s heat during the day. Here you can work protected from the elements with plants which are sheltered from the wind and rain and can enjoy day temperatures which are appreciably higher than the warmth outdoors.
Tomatoes are the favourite crop, during the rest of the year there are cuttings to take, seeds to raise and vegetables to force on. The range of the greenhouse is limited. You cannot grow frost-sensitive plants between late autumn and mid spring unless you provide heat. The usual practice is to turn it into a cool house (minimum temperature of 45 deg. F) and so open a whole new world. Now ‘greenhouse plants’ can be grown – Palms, Orchids, Fuchsias and so on. Half-hardy bedding plants can be raised for the garden and a year round display of blooms can be created for either greenhouse or living room. The installation of a heater transforms growing under glass into a year-round hobby.
An average sized greenhouse (8 ft long x 6 ft wide) would cost somewhere in the region of £200 – £300 if staging etc. is to be fitted. Before making this investment, carefully consider the points not made in most textbooks. Constant attention is needed, and this means every day during the summer months. There is watering, feeding, ventilating, misting and so on. There is also the fuel – keeping an 8 x 6 house at a minimum of 45 deg. F will cost over £100 during an average winter.
The purpose of the previous paragraph is not to discourage you, it is to avoid adding to the number of greenhouses owned by people with limited time to spare who after a year or two allow the structure to become a home for pots, boxes and various pieces of household equipment.
On a much more encouraging note, most people who buy a greenhouse run out of space for all the exciting things they want to grow. For them there is a different warning. If you have the time, money, and are keen on growing things – buy the next size larger than you have planned! Keep it as a cool house – the attraction of having a warm house (minimum temperature 55 – 60 deg. F) for exotics is obvious, but your fuel bill could be as high as £300 per year. Stove houses (minimum temperature 65 deg. F) have almost disappeared.