Grasses in the border

Autumn is an exciting season in the garden; the colour palette turns to russets, oranges, deep reds and a whole spectrum of gentle buffs. The leaves of deciduous trees transform from summer dull green to vibrant shades that shine in the lowering autumn light.

September and October belong to the ornamental grasses, when many will be reaching their peak. To get the full benefit of their beauty, most are best planted backlit by the sun. The seedheads look stunning encapsulated with frost and provide a source of late season food for foraging birds.

A firm favourite at Rosemoor is Miscanthus sinensis 'Morning Light' AGM - subtly variegated, it will grow large, yet it is compact. Pink feather duster flowers emerge in early autumn, turning silvery beige as they set seed. M. sinensis 'China' AGM in the Hot Garden always impresses, with large panicles of silky flowers in early autumn.

Our native purple moor grass, Molinia caerulea subsp. arundinacea, has a graceful elegance, moving with every breath of wind. We use them in the Foliage Garden, either side of the path, so you brush against them as you walk onto the lawn.

Stipa gigantea AGM (golden oat grass) is used in the same way and although tall, it does not dominate, as the plants beyond can be seen through the graceful oat-like panicles, giving added depth to the border. Stipa tenuissima AGM (Mexican feather grass), is evergreen and is best in full sun and a lighter soil. It gives a delicate, fountain-like effect, dancing in the breeze and you cannot help but run your fingers through the soft feathery panicles. Groups of five or more will give a ripple effect as waves on a gentle sea.

Another tactile genus is Pennisetum (fountain grass) which have softly hairy flowerheads in early autumn, so plant within easy reach of outstretched fingers and where the early morning sun catches the dew collected by hairs on the flowerheads.

Panicum virgatum 'Northwind', up to 2m tall, is a fabulous plant, bolt upright with bright blue-green foliage lasting well into winter. We use it in the Cool Garden, repeated in groups to provide a structural contrast with the rounded shapes of clipped Pittosporum tenuifolium 'Golf Ball'.

Panicum virgatum 'Shenandoah' AGM, P. virgatum 'Hänse Herms' AGM and P. virgatum 'Squaw’ all have striking blood red tips to their mid-green leaves. These plants make a great combination with dark leaved plants such as Phormium tenax 'All Black' or the bright oranges and yellows of Crocosmia, Rudbeckia and Kniphofia cultivars.

Grasses can be used with a multitude of autumn flowering plants. For further inspiration, visit the Plant Heritage Autumn Fair here at Rosemoor on September 11th and 12th. Specialist nurseries will tempt you with a delicious array of plants, many rare and unusual, for your autumn borders.

The qualities grasses bring to the garden are incalculable; delicate autumn flowers that can endure through winter; a variety of leaf texture and of form; the way they catch and hold the light, seasonal changes and their sociability with other plants.

Top tips for early autumn

Spring bulbs

October is a good month to buy and plant spring flowering bulbs including daffodils, Crocus, Muscari and hyacinths. Plant tulips in November or December, when colder weather reduces the risk of disease.

Try large groups of species Narcissus such as N. obvallaris AGM in the lawn, border or pots to make an impact.

Muscari makes a good edging to borders or in containers. We use pale blue ‘Valerie Finnis’ which also attracts pollinators.

For something a bit different, you can try Scilla 'Blue Giant' which will produce a carpet of starry blue flowers with pale centres at a height of just 15cm.

In the vegetable garden

Dig up remaining potatoes before slug damage spoils them.

Plant out spring cabbages in October.

Divide established rhubarb crowns to create new plants.

In the ornamental garden

Divide herbaceous perennials (every 2-3 years) including ornamental grasses, to ensure healthy, vigorous plants and to multiply your plants.

Late autumn is a good time to plant herbaceous perennials, trees and spring bedding. Temperatures have cooled and soil moisture increased allowing plants the chance to get their roots down before the first frosts.

Prune climbing roses in late autumn.

Sheila Dearing, RHS Rosemoor

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