Penstemon ‘Andenken an Friedrich Hahn’, also known as Penstemon ‘Garnet’, is a bushy, semi-evergreen hybrid with narrow dark green foliage. It grows to around a metre tall and has erect spikes of tubular bell-shaped, deep red wine-coloured flowers 3cm long, with delicate white flushing in each flower’s throat. It flowers from mid-July until late September.
You can see it growing near the Keble Gate in University Parks. ‘Garnet’ does best in moist, well-drained soil. It can tolerate an exposed site but does better with a little shelter. Members of the large Penstemon family generally like a sunny spot but are hardy through the winter. Regular dead-heading of the faded flowers will prolong the flowering period, so cut them back quite hard in the early spring. If you want to know more, there’s is a good book by D Way and P James entitled ‘The Gardener’s guide to growing Penstemons’, which gives a lot of detail about this interesting group of plants.