Plant in full sun to light shade in average to well-drained soil and water regularly to occasionally - less in the shade. Hardy to below 0°F - to USDA Zone 6 (and is listed by some to Zone 5). While typically prostrate it can climb higher by scrambling on adjacent plants or other supports; cut it back as needed and cut to the ground in late fall. Geranium 'Mavis Simpson' is a long-cultivated sterile hybrid that is the presumed result of a cross between Geranium endressii and G. traversii. It was discovered as a chance seedling at the Royal Botanic Gardens at Kew and named for a garden staff member who found it. In England, where it has been cultivated for many years, it has proven itself to be a great hardy garden plant that exhibits hybrid vigor and blooms over a long period of time. It was awarded the 2002 Great Plant Pick from the Elisabeth Carey Miller Botanical Garden and winner of the Royal Horticultural Society (RHS) Award of Garden Merit (AGM) in July 2003.

The etymology of the genus name Geranium, and the family Geraniaceae, is derived from the Greek word, 'geranos' which means "crane" from the seed capsule's resemblance to beak of this bird. It is a large genus with over 430 species distributed throughout most of the world, except in lowland tropical areas. We grew this plant at San Marcos Growers from 2007 to 2009. 

The information about Geranium x riversleaianum 'Mavis Simpson' displayed on this web page is based on our research conducted in the nursery's horticultural library and from reliable online resources. We also include observations made about it as it grows in our nursery gardens and other gardens we have visited, as well how the crops have performed in containers in our nursery field. We will also incorporate comments we receive from others and welcome hearing from anyone with additional information, particularly if they can share cultural information that would aid others in growing this plant.