This hardy perennial39s semi45evergreen foliage is complemented by its plum coloured flowers these bell45shaped blooms appear on upright spikes in the spring summer and early autumn they can be easily distinguished by their white throats which make their purple petals appear all the more vivid however penstemon 39pensham plum jerkum39 doesn39t just look pretty the plant is extremely weather resistant because it39s been bred to survive in low temperatures this quality