SITING THE GREENHOUSE
If possible, choose an open site where it can get all the sun available unless you are only interested in shade-loving plants.
The conventional rectangular greenhouse is best orientated east-west so that the best use can be made of winter sunlight. Also it may then only be necessary to shade the south side in summer. It is wise to put the greenhouse as near the dwelling as possible. This allows convenient running of electricity and mains water to the greenhouse. It also means less walking about in the open for the gardener during rainy or snowy weather and the greenhouse is more likely to get regular visits. Siting the greenhouse near the dwelling is particularly desirable if you have a hot water boiler that needs regular stoking or fuel to carry about.
Make sure the site is well drained. Hollow ground is best avoided since it can attract frost as well as water. On very exposed sites some form of windbreak on the side of prevailing wind is desirable. This can be a belt of conifers (small ones) at a reasonable distance so as not to cast shadow, or something like a wall or fence. don’t have trees anywhere near. They cast shade, make the glass dirty, endanger it by the possibility of falling branches, and may harbour pests and diseases likely to attack greenhouse plants. Their roots may upset foundations too. As already mentioned, a potting shed near at hand is desirable. If the ideal site is not possible, don’t be deterred from having a greenhouse. You will merely have to select plants that like the conditions you have to offer – theres always something that will grow anywhere.
POSITIONING HINTS AND MAINTENANCE
Putting up a prefabricated greenhouse is simple and it can often be done without help in a weekend or so. Elaborate foundations are rarely necessary, but when a frame is to be erected on dwarf walls of brick or concrete some care must be taken. It is wise to get a professional bricklayer to carry out the work if you are not familiar with such a job. Plans for the base are issued by the makers of the frame.
With most prefabricated greenhouses it is possible to obtain plinths of concrete to set them on. This gives an excellent firm foundation easy to lay. The ground should of course be properly levelled and firm. don’t use freshly dug and cleared ground unless it is well firmed. The manufacturers always issue erection instructions and preparation of the site hints. When it is necessary to make some form of concrete foundation it is usually easily done by digging a shallow trench and filling with a very fluid mix of concrete which can find its own level.
Concrete blocks or bricks can be set on top if necessary. All greenhouses with boarded base or glass-to-ground are best given a layer of brick or concrete to raise them just above ground level. If concrete plinths are supplied these will be adequate. This is to prevent the glass becoming splashed with mud from roof drip.
It is also wise to make a path of concrete or paving slabs close up to the glass and surrounding the house again, to prevent splash and also so that access for cleaning and maintenance can be achieved.
A prefabricated greenhouse is usually supplied with the glass cut to size. Should it be necessary to cut glass, place it on several layers of newspaper, mark the line of the cut with a wax pencil or ink pen, and score along the line with an ordinary steel wheel glass cutter available from any builders merchant. Use a straight edge to guide the cutter. A characteristic harsh hissing sound is emitted if the cutter is scoring the glass effectively.
Keep the cutter upright and press down firmly. Turn the glass over on the paper and then tap along the score mark with the hammer part of the cutter. The glass will usually crack easily along the line and can be pulled apart. Narrow edges can be removed by levering off with the notches in the glass cutter.
Never put putty over the glass when glazing a greenhouse. The putty is used as a bed for the glass. It should not be used to fill in the angle between the glass and the glazing bar as in domestic window glazing. Always be certain that the surface to be puttied is clean, free from flaking wood or paint, and dry.
Cedar is best coated with a solution of shellac in methylated spirit first (knotting). This gives better adhesion and seals in natural oils. Ordinary woods can be painted Erst.
Lead paints are no longer used or recommended for greenhouses. Lead compounds can dissolve in condensation and the drip may convey poisonous salts to salad and other edible crops.
Most modern, quick-drying, hard gloss paints are suitable for greenhouses, but obviously the surface must be properly prepared. For sealing cracks and leaks, glazing tapes are useful, and there are a variety of widths and types on the market.
For cleaning glass a solution of the water softener Calgon can be used. Just brush on with a soft brush and rinse off with clean water. This chemical is relatively harmless to plants and most greenhouse framework. In obstinate cases, a bath stain remover can be used, but this must be applied with care and kept off framework in most cases. It will generally clean off the most difficult grime including lime deposits. It should also not be allowed to contact plants. Use according to label instructions.