Carol Klein heralds the season with glorious grasses and she answers your questions
Golden and glowing in autumn light, they're at their peak now
One of the joys of having all our garden in front of Glebe Cottage is we get a comprehensive view of it from our bedroom windows. Not only can we see a large part of the garden but we can also take in at a glance the big beeches which separate part of the garden from the wood beyond, and the field outlined in hedges and trees. Each morning it tells us about the weather but also puts us in touch with the season. From here we can watch the joy of spring unfold, be treated to the kaleidoscope of summer colour and watch it gradually mellow into the glowing hues of glorious autumn.
Within the garden itself we’re treated to these changes at close quarters and at this time the plants that are going through the most remarkable metamorphosis are the grasses. Though there are grasses which are noteworthy in spring and summer, it's now that the majority come to the fore. It's during September and October that they reach their prime.
Grasses are the most sociable of plants and love to mix and mingle with flowery perennials, witness any road verge or motorway embankment. The paramount consideration is which grasses will grow best. First and foremost we choose grasses that will love our soil, situation and the climate in our garden. Our soil is heavy and much of it is on the wet side; Molinia caerulea, the blue moor grass, will thrive here.
What a magical group of grasses they are, varieties varying in height and spread but all exhibiting graceful deportment, their two different personae emphasising the season. First, green, blue and purple, sometimes with dark stems, joining in with the late-summer kaleidoscope provided by phloxes, sanguisorba and the first of the rudbeckia. Then later, golden and glowing in the autumn light in close harmony with the russets and reds that abound in that season.
As you would expect from a moor grass, molinias prefer to grow in an open position where they can recite their soft, rustling poetry, blown this way and that. There are few height limitations in anyone’s garden and most of the group are light and airy, providing see-through features.
The sub species Molinia arundinacea provides the biggest group of these grasses. A personal favourite of mine is ‘Transparent’ and though this is a big grass it has a diaphonous presence and other perennial plants can be grown right up to its skirts.
For those on light sandy or chalky soils, pennisetum are a better option. They lack the stature of molinia or miscanthus but make up for it with a wealth of detail close to where their fascinating bottlebrush flowers can be enjoyed to the full.
Pennisetum orientale will feel completely at home in those conditions. It makes a dense clump, erupting with purple-pink bottlebrush flowers from July for months. Grow it where the sun can ripen its blades. Gardening in colder, wetter conditions, Pennisetum villosum would be a better bet. Many of the new pennisetum varieties and selections of Pennisetum alopecuroides have been developed in Holland and Germany. North American Panicum virgatum, the switch grass of the prairies, adds a different emphasis with twinkling inflorescences adorning its upright stems, from 1-2m (3¼-6½ft) tall, it's sometimes sea-green and blue, sometimes crimson and red, the season epitomised.
'The plants that are going through the most remarkable metamorphosis are the grasses'