Most wildflower seeds can be sown at almost any time, given the right conditions. However in temperate climates where these plants naturally occur, Autumn and Winter bring the rain while also having many sunny days. Sewing at these times in such areas generally gives best results.
The seeds germinate best at temperatures between 18o and 28o C meaning that, in colder climates, it may be better to sow in Spring or at earlier times under plastic or glass. While a cold snap with temperatures as low as 0o C can be a good time to sow as this helps to break the Summer dormancy of some seed types, it is best in most cases to sow after the risk of harsh frosts(eg. colder than -5oC) or heavy snow has passed. Use a glasshouse or make a small tent by placing a plastic bag over the seed tray.
In warmer or wetter climates it is always essential to use extremely free draining soil to avoid water-logging of the roots. Most Australian plants do not like boggy soils and may rot if exposed to such conditions for prolonged periods. It can help to build up the level of the garden bed for the plant to assist drainage. Clear mulch away from the stem of the plant to limit the risk of collar rot. In humid locations try to position the plants where good ventilation is available; a light to moderate breeze is always good for them.
The various types of Kangaroo Paw plants would be best avoided in wet tropical locations unless you are able to create dry, sunny conditions with light – medium humidity and reasonable ventilation. This would most likely mean a rather well set up glass-house suited to the purpose.
As always, in any location, much will depend on the local climate, soil types and the care and attention given by the gardener.