Easy to grow, Penstemons continue to prove a winner with most gardeners wanting a long flowering, easily cultivated specimen, floriferous and resistant to drought. They are not bothered by pests, tolerate lime happily and will stand up on their own without any need of staking. What more could you ask of them!
The flowers resemble those of the foxglove and indeed, are of the same family. The species are native exclusively to the USA where they are very hardy but because of our higher rainfall, not all Penstemons, particularly the hybrids, grown in this country show the same hardiness. Their ideal site is a dry soil (sandy, limestone or just a well-drained neutral one), low humidity and full sun. Their tolerance is greatly improved by being given these conditions.
Many of the European garden hybrids are derived from Mexican species. Planted in groups they make outstanding garden impact. As a general rule of thumb those Penstemons with finer leaves show more hardiness than those with broader leaves.
Technically they are sub shrubs and benefit from leaving the old stems on during the winter giving added protection to the crown. These can be removed mid spring when new shoots are appearing from the base.
Description format - plant name, description and height. Substitutes to the nearest colour will be made if no indication is given to the contrary.