In 2012 I took seed from a plant in the botanical garden of Gran Canaria (canarian Islands).
As far as I remember I sowed them in normal sowing soil with a cap on it until the first leaves showed. (I use to sow in boxes which are used for salads in supermarkets). There were so many that I gave away most of them.
They grow since that time but never flowered.
In nature they grow on the beach with a thick layer of sand between the bulb and the surface. So I planted them in a small high pot with about 8-10 cm soil on the bottom and the rest filles with sand.