David Chaplin, via email
I am seeking guidance on how best to protect some of the plants, including orchids and bonsai, in my Adelaide garden. The hot summer seems to destroy the plants, and the lack of sunlight in winter slows them down. It looks like a glasshouse would take care of my plants from late autumn to early spring, but I’m afraid they would cook in the direct sun in summer, when it reaches 40°C. How do I address such issues? I don’t want to invest thousands in a glasshouse, then find out later that I’ve done the wrong thing.
Elizabeth Swane says
Coming from a nursery background, where one of our tasks was to whitewash the glasshouses each spring, if you decide on a glasshouse, I advise you to opt for some sort of protection from the searing summer sun. Shadecloth is easier than the fiddly annual application of whitewash. There are various knitted or woven shadecloth materials available, with density of shade ranging from about 30 per cent to 75 per cent. Choose shadecloth based on the main type of plants you want to protect. Ferns, for example, require 75 per cent shade, general plants and orchids 50 per cent and vegetables 30 to 50 per cent.
Look closely at the types of greenhouses and glasshouses used by local nurseries. Also consider your budget, as there is a big variance in cost between a shadehouse and a glasshouse. Take into account the cost of power for seasonal heating and cooling. Good air circulation is also important. In Australia, we can grow a wide range of plants outdoors almost year round, unlike the Northern Hemisphere, where glasshouses are common in home gardens. A glasshouse does have advantages, providing optimum conditions when propagating or growing plants out of their favoured climatic zones, and allowing you to get the jump on summer crops, such as tomatoes.