Gardens can look a little sad at this time of year, so make sure you plant some late summer stunners

IF you’re after a plant that flowers later in the season, look no further than Actaea simplex (formerly Cimicifuga simplex) and its cultivars. Not only do they flower from late August through to October, they offer height and a certain dark drama wherever you find them.

I’m a big fan of lush, dark foliage, which many cultivars offer in abundance. Even when not in flower, Actaea simplex is an excellent architectural beauty, adding contrast to surrounding green foliage and bright flowers. The scented flowers are often white, sometimes pink, star-shaped and arranged along elegant spikes.

Actaea are best suited to cool, moist (but not waterlogged) soils that are neutral to slightly acidic. They also need shade or semi-shade. Choose a spot carefully, giving them room to grow, as they prefer not to be transplanted too often whilst establishing. Once your Actaea has matured and is starting to get too large for its space, you can lift and divide it in spring. Be aware that the younger foliage can be damaged by frost so choose sheltered areas for your divisions. If you prefer to collect seed this must be sown as soon as it ripens as it doesn’t remain viable for long.

This year I planted up some containers with Actaea simplex ‘Hillside Black Beauty’, surrounded by the painted fern, Athyrium niponicum ‘Red Beauty’ and the Korean Rock Fern, Polystichum tsussimense, the textured fronds of which both complement the darker foliage of the Actaea wonderfully. For added interest I also added Heucherella ‘Tapestry’ which has dark purple veins on green leaves to echo the Actaea and long-lasting pink flower spikes. This combination would also work well as a shady bed or border, though a bit too stylised for the woodland itself. Other suitable companions include Tiarella ‘Spring Symphony’ and Anemone × hybrida 'Honorine Jobert', whose white flowers are offset by the dark foliage of the Actaea.

Cultivars of Actaea simplex offer a variety of foliage which darkens to various shades of brown, purple to near-black. The following are worth considering:

Actaea simplex Atropurpurea Group is widely available and one of the few cultivars that can handle some sun. It can grow up to 1.8m and offers cream-coloured flowers. If that’s not tall enough, A. simplex ‘Prichard’s Giant’ is said to reach up to 7ft.

Actaea simplex 'Brunette' has very dark purple-black leaves, growing to 1.8m, whilst A. simplex ‘James Compton’ is more compact at 1.2m, but with arguably darker foliage.

For something more than just flowers, Actaea pachypoda (80cm) has fluffy white flowers that ripen into white berries with black dots that are set on red spikes, giving the appearance of doll eyes. The berries themselves are poisonous so it is not a child-friendly plant to grow.

I can’t write about late summer interest without mentioning one of my all-time favourites: Kirengeshoma palmata. I honestly don’t know why it’s not planted more abundantly. It is worth growing for the elegant foliage alone, but in August its buds open to become waxy, pale yellow flowers that complement the leaves and gently arching stems beautifully. This is a plant for sheltered, semi-shaded positions and will sit happily amongst hostas and ferns. A moist, humus-rich and lime free soil is required for it to thrive.