Cattleya plants like all other orchid genera require >good light + water+ good air movement so to grow Cattleyas successfully in South Australian Climate you will need at least a shade-house with 50%-70% shade-cloth having good ventilation and air movement for summer growing together with a fibreglass or similar covering for the roof for protection from our winter rains.
The house should be capable of being well ventilated in the summer months but also have to capacity to be able to close up during the winter months so as to retain winter warmth.
It is necessary to be able to damp down the floor in the summertime to create a humid atmosphere. To be able to retain this humidity the floor should be covered in sawdust/shaving, gravel. or bark.
Catleyas like most plants require as much light as possible not a direct light but diffused, so the leaves will not burn and unsightly to look at. A good guide to check if light is enough is to hold your hand over the plant and if it shows a slight shadow it is thought that’s about right.
Cattleya medium should be free draining and reasonably long lasting. Most growers use a bark based compost with other additives but as a guide 3 pots of medium sized bark 1 pot of horticultural type charcoal and 1 pot of shredded styrene foam mixed together form a satisfactory mix. Cattleya’s do not enjoy being over potted but should be contained in a pot which allows for 1-2 years space for growth.
This should be a high nitrogen type when the plants are showing either new growth or new roots, use on a weekly basis at half strength. When growth slows down and flowering commences revert to a low nitrogen fertilizer and blossom booster fertilizer NPK factor 11-13-16 or similar.
During Hot weather daily watering may be necessary to maintain humidity and moisture to the plant. In colder weather or winter weekly watering could suffice Cattleyas enjoy a damp moisture not continually wet nor must they be allowed to dry out completely.
Which type of Cattleya should grow cold
Most of the modern Hybrids have cooler growing varieties in their make up and will grow & flower in cold conditions. However a good guide to follow when purchasing your plant is to read the label and if it has Lc or Slc or C there is a very good chance it would be suitable for your conditions. A BLC type will also grow cold but prior to purchase check with the grower where he grows it.