Friday, 18 January 2013

Winter interest: RHS Rosemoor

Keeping a garden looking at it's best all year round can be quite a challenge, but with careful planting it is possible to keep interest in the garden for 356 days of the year. Choosing what to grow and where to plant it can be daunting, so for inspiration I visited the RHS Garden at Rosemoor, Devon, in the first few days of 2013.
Rosemoor's Winter Garden
Rosemoor's Winter Garden is a fine example of what can be done to keep interest all year round. Careful planting means that this area is far from dull at any time, but in the cold and dark days of winter this area really comes into it's own. Every plant here contributes colour and/or shape to the scene, while careful planting gives the area a sense of being open and light- very important when the winter light isn't very strong. Evergreens provide structure and bulk, while the coloured stems of dogwoods (Cornus cvs.) and willows splash colour, and the branches of deciduous trees add an ethereal touch. Some of the trees, white stemmed Betula jacquemontii and the russet 'Paperbark Maple' Acer griseum, also provide interest thanks to their colourful bark. These are trees to be cherished in a garden- beautiful in summer, awesome in winter.
The border near Rosemoor's visitor centre is packed with evergreens to provide winter interest
Plants of different heights provide added interest; in the picture below we can see how the bulky mound of Viburnum davidii (bottom right corner) works well with the mass of low (and here sadly chlorotic-looking) Pachysandra, which in turn enhances the scale of the Camellia behind. Even though all three (usually) have dark green leaves, the different heights of the plants create an interesting grouping. Note also how the planting on the left is made up of good blocks of planting, helping to create more impact- you can get away with one plant tucked in amongst others during the riot of summer colour, but structure and mass are vital for winter impact. 
Winter colour
Although winter is mainly the domain of the shrubs, a few well chosen herbaceous plants add to the winter interest. Sadly neglected for too long, Bergenias ('Elephant's Ears) are making a welcome return to popularity. These bold herbaceous plants are known for their big thick and waxy leaves, green in summer and then usually turning deep red for winter. These leaves hold up well during bad weather, only really being affected by the very worst weather that nature can throw at them. At Rosemoor there is a very good planting that uses a mass of Bergenia 'Bressingham Ruby' (which this year looks slightly sorry for itself after the appallingly wet 'summer' of 2012) and a carpet of yellow-variegated Acorus 'Ogon'. The genus Acorus is rather interesting; previously classed as a member of the Arum family, it is now believed that these are the survivors of an ancient race of grasses!
Bergenia 'Bressingham Ruby' and Acorus 'Ogon'
Winter interest isn't limited to a carefully chosen palette of special plants, it can also come from the remains of summer and autumn. Unless destroyed by vicious storms, the stems of perennials and grasses can proved structure and subtle colour in the garden during winter. In the Square Garden (below) the RHS gardeners have left the stems of Miscanthus, Eupatorium and dozens of other herbaceous plants standing- these stems seem to glow in the winter sun and, providing they are cleared away in time for the new shoots to grow in spring, they create interest in an area of the garden that would otherwise be bare at this time of year.
The Square Garden in winter
Of course bare ground isn't a bad thing; in the same way that a large lawn gives you space to appreciate the impact of large borders, so bare space around certain trees and shrubs helps them to stand out. Keeping the trunk of the beautiful Betula costata below clear allows the trunk to be appreciated, while a low carpet of an ivy enhances and compliments the interesting leaves of Ilex aquifolium 'Lichtenthalii'. The newfound space left by dormant perennials (those that have disappeared naturally or are deemed to be not structural enough to stay for winter) is often itself a real asset in the winter garden.
Betula costata

Ilex aquifolium 'Lichtenthalii'

The Heroes of Winter
Whether or not you're into the hundreds of Snowdrops loved by so-called Galanthophiles (I occasionally dabble in this world, but would certainly not profess to expertise) I defy anyone to object to snowdrops. Those pure white (occasionally yellow, but again Galanthophilia) flowers are a real pleasure and joy during winter. Either grown with winter season shrubs (as with the red stemmed Cornus below) or carpeting space left bare by perennials or annuals, snowdrops are a delight. Tough and charming, and everyone should grow at least some! I'll dabble in the murky world of 'when to divide your snowdrops' in another post.
Galanthus atkinsii with Cornus alba 'Sanguinea'
Evergreen ferns add a lot of interest thanks to their structure and texture; being spoiled in the South West, I would recommend Blechnum chilense (below), but this can be tricky to grow in some areas. A tougher fern that is very much worth growing is Polystichum munitum, but certainly the chunky fronds of Blechnum chilense is my winter hero.
Blechnum chilense
An excellent choice for a wall is Garrya elliptica, and in particular the cultivar 'James Roof' which has especially long catkins. If you visit RHS Rosemoor in the winter the long catkins greet you by the main entrance, and certainly seem to generate interest among visitors. A superb shrub and pretty tough although it often has spots on the leaves, and these are caused by the imaginatively named 'Garry Leaf Spot' (there is no cure, but on a happy plant it is barely noticeable).
Garrya elliptica 'James Roof'
Scent is an important part of the winter garden, and queen among the scented shrubs is Daphne 'Jacqueline Postill'. Although a fairly large shrub, this bold evergreen bares small flowers with an exquisite scent in January- this crisp scent carries well in the garden. Providing you have the all-important soil type for a Daphne (slightly acidic, not too nutrient rich so don't feed it too much, and uniformly moist but not waterlogged) your plant will thrive. Received wisdom is that Daphnes do not like being moved, but I moved a 10ft+ Daphne 'Jacqueline Postill' last winter, in far from ideal conditions, and the plant has recovered from it's shock and is flowering it's heart out 12 months later!
Daphne bholua 'Jacqueline Postill'
Mahonias are a very underused shrub. OK, they're big and most are prickly, but in winter the deliciously scented yellow flowers are sublime. Given that not every bee species hibernates the Mahonias provide solidly reliable sources of nectar for bees when it's warm enough for them to fly. Mahonia x media 'Charity' is well known and nice enough, but M. x media 'Buckland' (below) is a nicer cultivar, as is M. x media 'Winter Sun' (a paler lemon yellow flower).
Mahonia x media 'Buckland'
Mahonias share a trait with another fabulous winter flowering shrub, the Witch Hazels (Hamamelis) – in both cases the yellow flowered cultivars are known for their scent, while red flowered cultivars are all but scent free. Having said this I don't doubt that there is some serious breeding work going on somewhere to rectify this, and even now there may be new cultivars on the market that combine red flowers with excellent scent... if you know any please get in touch! While the scent of the yellow flowered Hamamelis is a real treat during winter, the rich spice red flowers of Hamamelis x intermedia 'Diane' (below) are well worth compromising scent for.
Hamamelis x intermedia 'Diane'
You can't garden for winter scent without using at least one superb winter flowering Viburnum, and arguably best of these is V. x bodnantense. There are two cultivars that I would recommend, the well known and ever popular V. x bodnantense 'Dawn', and the equally good although less well known V. x bodnantense 'Charles Lamont' (below). Either or both are fantastic shrubs and deserve to be grown in any garden. Oh, and the corrugated leaves are interesting in spring and summer, and then there is usually very good autumn colour from both too!
Viburnum x bodnantense 'Charles Lamont'
Another Viburnum worth growing is the evergreen Viburnum davidii. Making a handsome low mound of large leaves, this Viburnum is an important structural plant for the garden. Sadly the flowers are of no great consequence, and the shiny black fruits are only borne on female plants (and plants of known sex seem scarce for some reason!), but the bold foliage makes up for these shortcomings.
Viburnum davidii
This is by no means a comprehensive list of good plants for winter interest, instead these are some of the plants used to great effect at Rosemoor. I haven't included the willows and dogwoods grown for their stem colour- these could easily warrant a blog entry of their own!

The RHS Garden at Rosemoor is a real gem and is well worth visiting at any time of the year. Originally set around an old Devon farmhouse, the garden has grown and developed since the garden was given to the RHS in 1988. Now it boasts a series of gardens set around themes, as well as large borders and an arboretum. Let's not forget the Winter Garden! Visit the Rosemoor pages on the RHS website here.