Friday 23 March 2018

Diarmuid Gavin: How ornamental grasses can bring life to your garden this autumn

After a summer of blooms and colour, enduring ornamental grasses really come into their own this time of year

Mixed perennials and ornamental grasses in late summer border, September
Mixed perennials and ornamental grasses in late summer border, September
Pennisetum alopecuroides
Pampas Grass

What we term 'the Irish landscape' has always been an evolving picture, whether deciduous woodlands, peat bogs or farmed acreage. But our small island tends to be defined the world over by one colour - green!

In the gardens we create, however, we have adopted plants which have originated around the world, and in many cases we love them because they put on brilliant displays of colour when they flower.

Flowering is one of nature's ways of ensuring that plants are propagated, so often nature will conspire to produce bigger and better blooms in order to attract pollinators - insects, bees, butterflies moths and birds.

However, some of my favourite plants are not showy types in that sense. I love all types of what we term 'ornamental grasses'. This appreciation started because of a very non-garden grass - the dense, grey-green tufts of marram grass that are a familiar feature of our coastal sand dunes. Its spiky leaves feature in many games during long summer picnics at the beach, but marram grass is not just a convenient hiding place in Brittas Bay or Doonbeg. It also plays a vital role in stabilising the dunes, its fibrous, matted roots binding the sand down. Well-adapted to a harsh life at the coast, its glossy, rolled-up leaves protect it from drying out.

In our gardens, grasses have great versatility, there are varieties suitable for both sun and shade positions, damp or dry conditions. Taller columnar types make good focal points or upright accents in a border while the fountain shape types look really well in pots.

Grasses come into their own at this time of the year. Many ornamental grasses do flower, keeping us and our important pollinators happy. Contemporary gardening relies on them to provide interest once summer colour has faded. Not only do they tend to come into flower later, they are often valuable in winter as their sheaf-like flowers retain their silhouette. And as the sun gets lower in the sky, some magical effects can be achieved as the almost horizontal rays of sunshine illuminates their beauty.

They are relatively low-maintenance, though if you have a lot of them the annual cutting back can be quite a job. For even less maintenance, choose evergreen varieties such as carex morrowii. These can a get a little scruffy so can benefit from a cut back every few years to allow for fresh clean growth. And some can be quite invasive - much as I love stipa arundinacea for its leaf colour and the clouds of bronze flowers, it does self-seed absolutely everywhere.

Hakonechloa is the Japanese forest grass. It has a beautiful dome shape which I have dotted through my mixed borders, along with dome-shaped Buxus. The surprise every year is the amazing orange autumnal colour - really beautiful and a great candidate for a large pot.

Stipa teniussima is known as pony tail grass or Mexican father grass and is a small, fluffy blonde number. It loves the sun and is wonderful for introducing a light feathery effect.

Pennisetum alopecuroides

Many grasses invite you to feel their texture. Best amongst these are the pennisetums with their fluffy bottlebrush flowers. Pennisetum alopecuroides (above), 'Little Bunny', has delicate flowers in pink while pennisetum hameln has purple-tinged plumes. They're good choices for the mixed border or in patio pots.

Miscanthus is one of the later grasses to flower. Generally, they are better for a large garden as they are quite bulky and tall, for example miscanthus sacchariflorus which has large bamboo-like stems. For the smaller garden miscanthus 'morning light' with creamy margins would be better. Good flower tresses can remain over-winter - cut back to ground in spring.

Stipa gigantea is the graceful giant in the grass world, achieving heights of over 2.5 metres. A huge fountain of golden oat-like flowers make this a dramatic specimen plant in any garden. It's a grass that doesn't like disturbance so don't try division on this one.

Pampas Grass

Pampas grass (above) isn't everyone's cup of tea and there are wonderful urban myths involving the messages and signals being sent out by frisky homeowners if they display clumps of this dramatic grass in front garden lawns.

However, cortaderia richardii is worth growing, even if it gets the neighbours talking. It's a more refined version well worth seeking out - very elegant arching plumes.

If you like the unusual, you'll appreciate imperata cylindrica 'Rubra' - Japanese blood grass. Flat lime-green leaves that turn blood red from the tips towards the bases make a dramatic display. Grow in full sun or partial shade but keep them moist for optimal appearance.

So, I'm off out now to cut the grass, reminding myself of the importance of this species whether underfoot or in the borders.

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