It’s also easy to grow them in any reasonably moist, free-draining soil in full sun or light shade. With no major pest and disease problems this group of perennials pretty much ticks all the boxes.
Throughout the flowering season it is beneficial if you regularly deadhead. Removing the spent flowers down to a new side shoot or a node will encourage new flowers and prevent the plant from putting energy into producing seed.
As the flowering season has come to the end for most perennials it’s a bonus there’s still the odd bit of colour from the penstemons. They will flower a little over the winter months.
Best cut them back as they can become woody and leggy if not pruned annually. The right time to prune is when new shoots are growing strongly from the base and the danger of the worst frosts is gone. Replace or divide every few years; they’re very easily grown from cuttings and some can be divided if the base is not too woody.
At Dunedin Botanic Garden, there’s an attractive display in front of the winter garden glasshouse: penstemon "Hidcote Pink" growing between the iceberg roses and near the grey foliage of artemisia ‘‘Powis Castle’’. There are many different penstemons planted throughout the botanic garden.
