NotaNumber,
The dry season, in the region that petiolaris grow in, is summer in Australia. Petiolaris complex are in active growth during the winters, which, again in the areas where Petiolaris complex grow, are warm and wet.
While there may be a photoperiod trigger I suspect it is more to do with response to moisture. If you read any of Lowrie's literature, he notes that, by and large, the majority of plants of many of the species tend to be found in depressions or against stone faces where moisture retention is longer than the surrounding open areas. Plants found in such areas will be in active growth while another plant of the same species in a less protected but otherwise identical area are dormant.
D. fulva is a moderatly easy plant. It is not as easy as paradoxa so do not expect windowsill growth. Probably ranks in with petiolaris or falconeri for ease though.
* Summer: December to February
* Autumn: March to May
* Winter: June to August
* Spring: September to November
Australia's tropical regions
The tropical regions of Australia are in the north of the country. They include the central and northern parts of the Northern Territory and Queensland, and the northern parts of Western Australia. The weather in the Australian tropics has two very different seasons: the wet season and the dry season.
The wet season lasts about six months in summer and spring, between December and March. It is hotter than the dry season, with temperatures between 30 and 50 degrees Celsius. This is because of the high humidity during the wet, which is caused by large amounts of water in the air. During the wet there is a lot of rain, which frequently causes flooding.
The dry season lasts about six months in autumn and winter, usually between May and October. Temperatures are lower and the skies are generally clearer during the dry. The average temperature is around 20 degrees Celsius.
The 'build up' is the humid time of year between the wet and dry seasons. It usually lasts for three or four months. Things become quite tense during the 'build up' as people sit and swelter in the humidity while waiting and hoping for the first rains to come. The humidity continues day and night with no respite, so when the rains finally do come everyone enjoys their cooling relief.
Rain drops in summer but the temps are pretty constantly warm. Only 10 degrees average variance over the course of an entire year is pretty stable temp wise.