October is the traditional end of the gardening season but not of garden interest. Mid-summer flowers which have gone over punctuate late season perennials which are still in their prime as the angled light of autumn picks up details lost to the saturation of July and August.
Aster Prairie Purple
Aster Anja’s Choice
Autumn colour of Gillenia trifoliata
Some plants, like the Asters, have been very slow flower this year and these will carry the season well into winter. Like the summer perennials you should be scared of plants whose flowers have finished and their seed heads will remain and their foliage often has good colour. Gillenia trifoliata, for example, finished flowering some time ago but it’s small black seed heads presage exceptional autumn foliage colour and it continues to impress. The Asters too will look great even once they have finished with their little daisy seed heads creating a haze.
Rudbeckia fulgida var. deamii
Flower heads of Echinacea in autumn
Rudbeckia have a long flowering time with large, mostly yellow daisy flowers and good black centres. These again will remain and, like Echinacea, provide a winter larder for birds and great texture in the late season garden.
Verbena bonariensis cuts a sharper profile at this time of year floating on slender vertical stems which burnish to a soft grey and will be cloaked in cobwebs caught by cold morning’s dew.
Down below, Ceratostigma plumbaginoides, is an exceptional spreading ground cover for sunny spots, tolerant of reasonable drought once established. It appears late with spoon-shaped glossy green leaves. In Autumn apple red buds appear before unexpectedly blue flowers just as the foliage begins to turn the most phenomenal reds and oranges.
Persicaria amplexicaulis is perhaps the hardest working plant in the garden through the late season. An essential garden plant, it’s slowly spreading rhizomes can form large clumps of attractive foliage which will smother weeds and cover the ground. From August to November masses of slender flowers heads made up of small flowers humming with pollinators rise above the foliage. Various colours are available but darker forms like P. ‘Blackfield’ are especially good with the colours of autumn. Ideal conditions are sun with heavy damp soil, where they will form very large plants, but they are tough enough to survive almost anywhere.
Grasses in autumn
What all these plants on their own miss is something to stitch them together. The grasses are the real star of the autumn show and these are what will carry your perennial border through until March. Grasses form the essential structure of an open border without the need for shrubs and their airy habits with flowers that turn silver and gold through winter are the perfect foil for reds, yellows, blues, and, ultimately black, of flowering perennials.
The most striking of the grasses at this time of year is Pennisetum macrourum. This grass forms a ‘good sized clump with upright bottle brush flowers from September which catch the light in the most dramatic fashion. It’s almost impossible not to be distracted by them.
Miscanthus are another fabulous late season grower with a variety of foliage forms and habits and elegant tassel flowers, typically with red tones when they emerge, turning silver through winter. Miscanthus nepalensis is a little different from the others and particularly striking with soft arching flowers in the most impossible silver-bronze. A very delicate looking plant which is actually very tough.
Pennisetum alopecuroides Hameln
Panicum, the switch grasses, are North American prairie grasses which produce tall slender foliage and a mist of little purple-tinted flowers in October which look wonderful backlit by the sun. The foliage can be green or green-blue and turn to lovely autumn colours in November, purple and yellow respectively. They appreciate an open sunny location where they take advantage of summer heat.
The fountain grasses, Pennisetum alopecuroides, are the other grass to consider for autumn and winter interest. These build over time into a large ‘knuckle’, a but like a fern, which will produce a dome of fine green foliage. In autumn, fluffy bottle brush flowers emerge in creams or purple and look well for weeks. They are best with a long hot summer and should be planted in your sunniest spot.