The Chelsea Flower Show may still be the top social date in the gardening calendar, but for me the most exciting garden opening this year has to be the 250-hectare (620 acre) Olympic Park, masterplanned by American landscape architect George Hargreaves in association with British practice LDA design. Within this are a series of compelling garden spaces by the talented garden designer Sarah Price, but perhaps the most innovative will be the 30 hectares of meadows that stitch the scheme together. These have been masterminded by two Sheffield University academics, Professor James Hitchmough and Dr Nigel Dunnett, and they should be spectacular.
The Sheffield duo have developed the techniques of creating meadows into a fine art. They have worked for the past 10 years on devising seed mixes to create low maintenance, colourful vegetation that could take the place of some of the high maintenance, stuffed shirt bedding schemes in our public parks.
The Olympic meadows will comprise colourful fields of annual flowers (exotic and native) and separate areas of native wildflowers that will be cut about six weeks before the games so that they regrow and flower on cue. They will be so packed with bloom that they will seem quite different from the grass-dominated hay meadows we are used to, and this is done intentionally to give greater impact over a short season. After the Olympics the perennial meadows will be over-sown with grass and they will gradually become more “normal” looking as the amount of grass in the mix increases.
A third type of seeding has been pioneered by Hitchmough and while this is not represented in the Olympic Park it is perhaps the most innovative and daring of all. This is the exotic perennial meadow.
Hitchmough looked at a range of species that would also extend the usual flowering season of the European meadow well in to summer and autumn and came up with a palette dominated by North American prairie plants with colourful Echinaceas, Rudbeckias and Asters forming the mainstay but with other plants from similar climatic zones all over the world.
In the resulting meadows there is a good balance between taller show stoppers such as Silphium laciniatum (the 2m tall compass plant) and more humble mound like plants that cover the ground. Typically a meadow might contain 30 or 40 species and many of them will be unfamiliar to everybody other than the most seasoned gardeners. So the mix might include South African Helichrysum, Asian Scutellaria, various different Penstemon species from Mexico and even a hemiparasite, Castilleja integra, which derives part of its nutrients from tapping in to the roots of other plants growing around it. It’s a catholic, pan-global bunch. Because the seedling plants cannot compete with native weeds, it is very important that the seeding is done under controlled conditions. It must be scattered on to a 75mm layer of coarse sand, which makes a well-drained seed bed and suppresses the weeds in the soil underneath, then the bed is covered in a loose weave jute fishnet (manufactured for erosion control on slopes), to prevent birds and squirrels digging it up. Add water and watch it grow.
It is eight years since Hitchmough sowed the first meadow in Sheffield Botanic garden, which is still going strong. Since then I have collaborated with him on five different projects using this technique, including a post-graduate garden for Corpus Christi College in Cambridge, an acre of meadow around a company headquarters in Kent and perhaps most prominently, a meadow of about 500 sq metres next to the Royal Horticultural Society’s Bicentenary Glasshouse at Wisley.
The technique is now getting more attention. One of the attractions is cost. Seeding is cheaper than conventional planting because even though seed is eye-wateringly pricey it goes a very long way. A bag of seed for a new meadow in my own garden, which I sowed 18 months ago, (it was, I admit, the equivalent of a super luxury muesli) set me back nearly £6,000 for an area of 1,400 sq metres. This would amount to £17,000 an acre. But the material and establishment costs in the first year are probably less than half that for conventional planting and in the second year the real savings begin. This is partly due to the weed-suppressing layer of sand, but is mainly because the density of plants is about 100 per sq metre compared with about seven per sq metre in a planted area, so there really isn’t much room for other stuff to get in. Also, in contrast to the annual meadows, you don’t have to redo it every year.
The technique, like seeding of native meadows, works best on sites of comparatively low fertility, so there is no need to improve the soil. Maintenance is limited to the occasional bit of vigilant weeding and then burning it all in spring. At Wisley they estimate the maintenance, four years on, to be about 60 per cent of that in the conventionally planted areas, but on other sites where burning is practised it is more like 10 per cent. The Sheffield site is weeded and burnt just once a year. The flowers and grasses, being used to this sort of treatment on the prairies, don’t turn a hair.
So far, Hitchmough is probably the only person in the UK competent to devise a seed mix for an exotic meadow, but he is collaborating with German seed producer Jelitto, which is the leading European supplier of perennial plant seed, to devise a number of mixes for different soil types (not available yet), so that the technique would be more available to the general public.
I think it is realistic to imagine the exotic meadow becoming a regular feature in our gardens and parks, sometimes interwoven with other types of planting and sometimes as the glue that holds the whole composition together. The gardening then becomes more about managing a complex and dynamic patch of vegetation rather than cosseting lots of individual specimens. More about giving a gentle steer rather than a serial makeover. For many, this less interventionist, more ecologically inspired approach will have considerable appeal, especially when the result is a complex naturalism that is all but impossible to achieve by conventional means.
Tom Stuart-Smith has won eight gold medals and three best in shows at Chelsea