Detailed instructions on cultivation of the Madagascar periwinkle are available.  As evidenced by its widespread naturalization in warm areas, the plant germinates readily from seed, requires little water or fertilizer, and is not choosy about soil type (though deep digging and use of compost are recommended to provide a loose, well-drained soil).  Pruning is advised to maintain a good shape, and the root ball of potted plants can also be pruned back annually.  Plants to be kept alive in hibernation over a temperate winter must be kept indoors, preferably at a temperature of at least 12°C.  Snoeijer (1996) found that seed germination is improved by covering a pot with plastic for increased humidity, sowing the seeds on top of the soil, and exposing them to light; however, other authorities favor germination in the dark.  Plants may also be propagated by cuttings.

References

A Guide for Commercial Production of Vinca

Dave’s Garden

Institute of Food and Agricultural Sciences, University of Florida

Snoeijer, W. 1996. Catharanthus roseus, the Madagascar Periwinkle, a review of its cultivars. Wageningen Agricultural University Papers 96(3): 47-120.