Thursday 19 September 2019

Diarmuid Gavin: Ornamental grass takes root

Stand-out grasses add useful ground cover and autumn texture

Fountain grass: Pennisetum
Fountain grass: Pennisetum
Pink dahlia

September in the garden has a distinct look as summer gently gives way to autumn.

Late autumn perennials display rich jewel colours such as red and pink dahlias, orange crocosmia, blue salvias and purple penstemons. It's also when many ornamental grasses are at their peak, with golden, silver and yellow flowers, bringing to mind fields of wheat and barley about to be harvested.

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Ornamental grasses have become hugely popular and with good reason. They can be utilised in so many different ways... from stand out as a specimen to massed planted drifts or useful ground covers. Grasses bring a different texture to the garden and interspersed among herbaceous perennials they create soft structural elements in the border and throughout the garden.

Your single specimen could be an elegant pampas grass, once considered naff but now edging towards being cool.

Surrounded by a lush lawn or a mass of late low flowering perennials they can look wonderfully dramatic.

Mass or drift planting makes a soft statement and is a good way to create a calm effect or deal with large tracts of gardens. They work well in a mixed border, a modern planting scheme as well as the cottage garden. They are the staple of 'prairie' style planting which uses ready available perennials and grasses to create a wild natural-looking border.

As with all planting, size and form is everything when it comes to grasses. They vary in size from the giant Miscanthus sinensis 'Goliath' which stands 2.5 metres tall to Deschampsia 'Tatra Gold', a neat little tuft with flowering stems that reach 30cm at most.

In general, grasses prefer a sunny position, but there is a grass for every location including shade if that's appropriate. Likewise there is a grass for every soil - some like it dry, others prefer to have their roots damp. Read the label when buying or if you're not sure, ask for advice - good garden centres and nurseries are full of enthusiastic gardeners who are delighted to share their knowledge and advice.

Here are some of my favourites that I find both functional and beautiful.

Pennisetum 'Hameln' - there are a number of varieties of fountain grass now available but for our climate, Hameln seems to be the most reliable for producing fluffy flowers. Prefers a sunny site with well drained soil and will tolerate drier soils.

Stipa gigantea - golden oats will reach 2 metres and over in the right conditions. It is one of the most magnificent grasses in full bloom and makes a striking specimen plant in the middle of a large border. Prefers well drained soil in full sun.

Pink dahlia

Calamagrostis 'Karl Foerster' and 'Overdam' are two very useful grasses - at 1.5 metres they have an excellent upright form and delightful blooms of soft seed heads that condense to a neater, narrower form over the season. They like full sun and moist soil.

Hakonechloa macra - Japanese forest grass is my favourite grass. I love its graceful green foliage and round mound shape. It performs in sun or partial shade so long as soil isn't too dry and the foliage flushes orange in the autumn.

Cortaderia richardii is a relative of the pampas grass and like his cousin needs a good bit of space. It's a large statement grass with beautiful feathery arching plumes. It likes moisture retentive soil.

Miscanthus have the most beautiful flowers which last well into winter. 'Ferner Osten' has silky purple heads which fade to silver - I have a row planted as a kind of hedge. 'Zebrinus' is an eye catching variegated plant with horizontal bands of yellow across the leaf.

READ MORE: Diarmuid Gavin: The autumn audit - it's time to get busy with that to-do list

Top Tip

Resist tidying up your grasses in autumn - many of their seed-heads will look good throughout winter - and you can chop them back in early spring to neaten things up.

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