Autumn in herbaceous borders
This article was first published on 15 May 2015.
Salvia Leucantha ‘Midnight’
Photo by the Otago Daily Times
Herbaceous borders are regarded as a summer flowering collection of plants but they can still offer colour and other features over the late autumn and winter months.
Choosing late-flowering perennials helps extend the flowering season. Sages are a good choice. Looking stunning now is Salvia leucantha 'Midnight' which has lots of lovely long purple flower spikes above a nice mound of grey green leaves.
Penstemon are a good choice too - they can flower right through till spring when you cut them back and start again.
Penstemon 'Hidcote Pink' is a beautiful, clump-forming perennial with bright pink flowers above lovely clean, green foliage.
At Dunedin Botanic Garden Alstroemeria and Dahlia cultivars help round off the display. Near the main gates, red flowers contrast with the stunning dark red foliage of Dahlia 'Fire Mountain'. It has plenty of flowers and buds to open but the fleshy foliage on dahlias and alstroemerias will be the first casualties here after a decent frost.
Some plants we don’t cut back till the spring as the faded flowers offer another feature - on a frosty morning the flowers on Sedum 'Herbstfreude' (autumn joy) look fantastic covered in frost and the attractive dry flower heads left on astilbesand monardas are worth keeping.
Perennials also offer autumn foliage colour. Hosta leaves splash into colour as the leaves turn yellow and orange before dying down to meet the winter.
Linda Hellyer is curator of the herbaceous borders at Dunedin Botanic Garden.