September can be a great month for time spent outdoors and in the garden. On the hills and along the coast, the skies are often clear, and the temperature is pleasant enough for long walks. In the garden, it's the perfect weather for planting: warm and rainy, so plants can establish their root systems before the cold weather sets in. It's also a wonderful time to plan next year's great adventures - whether new crops (berries galore) or new plans (a kitchen garden).
It's also a great time of year for colour, shape and texture in the garden. Here are a few of my favourite plants for September...
Abelia x grandiflora is a medium-size shrub with an arching habit. It's covered with small, creamy or pale pink bell-shaped flowers from mid-summer through to October. It really comes into its own in September, when few other shrubs are flowering. It prefers full sun and moist, well-drained soil, but it's also doing well for me in a sheltered but dry east-facing site, so you could stretch its reach a little.
Another interesting shrub is Physocarpus opulifolius. This has several cultivars, including 'Diabolo'. It is a tall shrub, growing to about 1.5-2m high, with wrinkled purple leaves ending in a graceful tip. The colour is similar to that of a purple beech (Fagus sylvatica purpurea), and is a lovely choice if you wish to create purple accents throughout your garden. It grows in full sun or part shade, and works well in the middle to back of your border. In summer it has clusters of small, white-pink flowers.
Of course, if you like purple accents in shrubs, then you can't go wrong with my absolute favourite, Cotinus 'Royal Purple.' The purple foliage become red-tinged as autumn progresses, while the pink-purple flower plumes are a sight to behold in summer. Almost delicious!
My favourite perennial for autumn is Penstemon 'Andenken an Friedrich Hahn' (syn. Garnet). I grew this in London, where it thrived despite heavy clay and a semi-shaded position. Penstemons are meant to be half-hardy, but mine are doing well here in Oxfordshire, where the frosts are heavy and last well into late May/early June.
Penstemon Andenken is not easy to get hold of, despite being well-known as the toughest of the numerous cultivars. But don't bother with many of the cultivars for sale - although they have large flower-heads, they're not tough, and the overlarge flower heads often droop unhappily.
To give penstemons a fighting chance, trim the foliage lightly in late autumn, after flowering, but wait until the spring to cut it back fully. This will provide some protection from frosts over the winter.
The other great perennial for this time of year, and for Oxfordshire soil, is the Sedum. It needs full sun and well-drained, poor soil to do well. There's a huge variety, from the small ground-creepers, to the taller, purple varieties like 'Morchen' (which can be seen at Waterperry Gardens). They're also great for splitting and potting on. I recently split and potted up several, and they're already ready for replanting after only 2-3 weeks, so they're a cheap way to fill your borders, or, if your garden is smaller, to add some colour to your patio plants.
Asters are also wonderful. We have too many of the washed-out pale pink ones in our garden, which are also prolific along the Thames this time of year. Choose, instead, some of the more striking cultivars, and consider visiting Waterperry Gardens for ideas - their aster display, along the main border, is amazing.
Cyclamen are lovely annual bulbs to pot up or plant in mixed beds for autumn colour, and I'm enjoying them right now.
Dahlias are, properly speaking, perennials, but are generally treated in England as annuals, as they are frost-tender. I first realised their potential when I visited a friend's garden in mid October. He had mixed a huge variety of dahlias together, higgedly piggedly, in one long border, and the view from his kitchen window was a sensational blaze of spiky, starry fireworks. This is the first year I've planted them. My display is not a patch on my friend's, but they're still a real pleasure to behold.