Add interest in winter with the shapes and sounds of grasses

by Tom White, horticulturist

By now, flowers and blooms are fading in the garden but many berries, evergreen foliage, seed heads and grasses add interest on a dull day. At RHS Garden Harlow Carr we leave as many of the herbaceous perennials standing as they provide a valuable food source for wildlife over the winter months, the exception being slimy or collapsed foliage which we cut back and remove. Hardy geraniums, hostas and agapanthus will certainly need some attention. It is often easier to cut these types of plants back now before too much decay sets in as they are likely to jam secateurs, making a clean cut and finish hard to obtain.

Grasses look good in an herbaceous border during the summer months but contribute greatly during the autumn and winter. However, at this time of year the Miscanthus species really shine and stand proud. They nod gracefully in the wind amongst late flowering asters. Even on a damp, dewy morning droplets of dew sparkle from the flower racemes. Their flower heads look stunning during the autumn and continue to dazzle as winter arrives. As neighbouring perennials retreat, grasses have an even greater impact.

Each grass has its own personality and best use. Small gardens couldn’t accommodate some of the larger grasses. One of my favourite small grasses is Molinia caerulea Subsp.caerulea ‘Overdam’ as it has vertical needle-like foliage and very refined upright flower stems. It holds onto its shape and structure well through the winter, making this a perfect candidate for a tight area. You could say Miscanthus are the king of grasses producing the finest seed heads. They are varied in height, colour, shape and plumes. Another favourite of mine is Miscanthus ‘Ferner Osten’ as it is more compact than some, having fine colour and shape, and works well mixed with perennials as it’s not too dominating. Although some of the larger grasses give good height and structure, choose carefully as they can tend to abscise during windy conditions; Molinia ‘Skyracer’ is known for this. Most grasses require a well-drained soil but Miscanthus and Molinias will cope with a heavier soil. The key to adding any type of grass to your border is drainage, as they don’t like to be sat in wet or water-logged soil: adding grit is a great way to help break up clay particles.

The seed heads of many grasses look great architecturally even if there is no colour, giving silhouettes as they stand proud on frosty, wintery days. By leaving the foliage this will also give tender grasses such as Pennisetums and Sesleria some winter protection. These are best cut back in early spring when you start to see the new green growth emerging from the base. Our big cut down and chop on the borders is February. By this time many of the plants are in need of a good cut back and tidy, having done their job over the winter, ready for the season to start again in the spring. When growth is starting to show signs of life and warming up you can begin lifting and dividing. It is best to wait till you see new growth as planting too deeply can result in the crowns rotting off, as will mulching too deeply.

Jobs for the week

* Clear fallen leaves from lawns and pathways to make leaf mould.

* Continue bulb planting for a spring display.

* Start putting together a seed list of your favourite annuals.

* Make sure any tender perennials have been lifted for winter protection.

With thanks to Tom White, Horticulturist at RHS Garden Harlow Carr

DIARY DATES

Friday 2 December: Meet the Artist – Emma Ball

Visit the RHS Garden Harlow Carr Shop & Plant Centre and chat to well-known artist Emma Ball. Emma will be on hand from 1pm to talk about her festive ‘horticultural hares’ watercolour designs – including a tea towel, apron and Christmas cards - produced exclusively for the RHS.

2 – 4, 9 – 11 and 16 – 24 December: Magic of Christmas

Get in the festive spirit with our Christmas Activity Hunt; put on your best Christmas jumper and join our fluffy polar bears and penguins in the photo booth for a festive family snap. Get creative in the glitter emporium and make your own ‘Thank You Santa’ Christmas Eve kit. Normal garden admission.

Saturday 3 December: Meet the Author – Rob Cowen

Head to Harlow Carr’s bookshop at 2pm for the chance to chat to Common Ground author Rob Cowen who will be on hand to sign copies of his book and answer questions.

November - March: Winter Walk 10-Year Anniversary Harlow Carr celebrates the 10-year anniversary of its Winter Walk this year. To mark the occasion, 5,000 irises have been planted and will bloom as the garden moves into early spring. Adorned with daphnes, witch hazels, birch trees and maples, the striking stem colours and variety of forms, textures and scents make this a must-see from November through until March. Normal garden admission.