Although a greenhouse may not be cheap a simple glazed building can open up a new world of gardening. With just a little heat to keep the frost at bay you can grow tender bedding plants from seed, hardy fuchsias and tender cuttings throughout winter and enjoy exotic fruit and vegetables and hot house ornamentals that won't survive outside.
Even an unheated greenhouse extends the gardening year providing protection for alpines and shelter for hardy seedlings and cuttings through the winter.
Where should I site a greenhouse? Location.
Before investing in a greenhouse first decide where to put it as this will effect the size and style. The best position for a greenhouse is in a sheltered, sunny spot that is not in shade for several hours each day.
Orientation. For the best light in spring, when sowing seeds position the building on an east west axis so that the longest sides follow a line from east to west. In contrast, for maximum sunlight in summer important for fruit and vegetables that need sun and heat to ripen the longest sides should run north to south.
Against a wall. If you plan to buy a lean to greenhouse it is best to locate it on a house wall that does not face directly south. Brick walls absorb heat from the sun and the house, which makes south facing greenhouses too hot in summer and inhospitable for plants even those that enjoy tropical conditions.
Water and Access. Think about access from the house ensure you have a path leading to the greenhouse that's wide enough for a wheelbarrow. A nearby water supply is useful.
What Size. The size and style of greenhouse depends on your budget but buy the largest structure you can afford. It is easy to underestimate how much space the staging will take up benches how many plants you wish to grow. Tender fruit and vegetables take up space and need plenty of light.
Choosing a Style. There a huge choice available so you bound to find one to suit your needs. In a small garden you may be looking for a greenhouse that's decorative as well as functional. Wooden framed buildings complement a naturalist setting and be a feature in themselves.
Hardwood frames are most durable but do ensure that the wood is from a renewable source and paint or treat them with preservative every couple years.
Aluminium frames not as attractive but they are light strong need little or no maintenance.
Ventilation. Good air circulation is a must. Before you buy ensure the total area covered by windows and vents adds up to at least one sixth of floor area, if it doesn't order more. Install vents on each side of the greenhouse just above or below the staging and the roof..
Where warm air escapes from the top vents and cool air is then drawn in from below. Make sure that windows and vents are not directly opposite each other to prevent air from blowing in one side and straight out the other without circulating.
Fan ventilation systems where a fan extracts warm air and automatic systems that open vents when temperatures reach a preset level are sound investment.
Lowering Temperatures. Blinds and shading washes help to lower temperatures reduce evaporation and protect plants from scorching sunlight. Blinds fixed to outside of the greenhouse are convenient as they can be rolled up or down as temperatures fluctuate.
Meshes and fabrics can be fixed to greenhouse windows as required but like washes they are designed to remain all summer.