I grow D.cistiflora, and they're easy if you live in Cape Town
South Africa, I battle with linearis though, but have a few in the
fridge at the moment, it being Winter here. Spring will determine how
well they've faired, having only had them for a short time.
D.cistiflora are Winter growers, very similiar to the tuberous
species of Australia, instead of the roundish tuber they have a fleshy
root +-12cm in adult plants, which sustains them through the dryer
Summer dormant period. Some areas become bone dry, eg. the West Coast,
but areas nearer the cape remain damp a few cm. below the surface, even
during the hottest of Summers. The soil is usually sand or clay with a
bit of organic matter thrown in, dead leaves, twigs etc. As a growing
mix I use 9 washed river sand to 1 Canadian peat (by Volume) for seed
(slow to mature) or leaf cuttings. In Autumn, with the onset of our
rainy season and the daily early morning mist the plants rapidly pop up
and produce rosettes with the upright stem following shortly. Average
temps. in Winter are: nights 5 degrees centigrade, days 20, on rare
occasions the temperature has been known to go as low as 0. Rainfall:
lots, but in bursts, 2-3 days solid heavy rain and then often 5-10 days
without any, never snows and no frost, except on the highest mountain
peaks, eg. D.acaulis area.
D.cisti have a variety of flower colour forms, pink being the most
common, many shades of, though. Other colour forms I have seen are:
white, red/crimson/scarlet, purple and a pale yellow/creamish,
apparently there is an orange, but have yet to see it.
Hoping this helps with cultural instructions.
Allen Lowrie (Australia) and the British CP Soc. could possibly
help with seed of different forms.
ALL THE BEST Eric Green