Mehndi / henna plants are available from garden suppliers on the Internet, but they do not do well in template climates. They are susceptible to many garden pests, and are fussy plants. Mehndi / henna grows well only in a climate where the nights are always warm, it never ever freezes, and there are at least 3 months of weather over 100 F every summer. Rajasthan (India), Israel, Egypt and places with climates like them, are excellent places to grow mehndi / henna.