A BURST OF COLOUR
As autumn sets in, Tom Stuart-smith’s experimental garden in Hertfordshire provides an eye-catching pyrotechnic display
As autumn sets in, Tom Stuart-smith’s experimental garden provides an eye-catching pyrotechnic display
Peep into Tom Stuart-smith’s prairie garden in Hertfordshire in midjune and you will be met by a sea of dense, lush green foliage – layer upon layer of texture and varying leaf shape, as the framework of mostly native North American perennials builds. Here and there, the fresh green is dotted with magenta pink as the first flower heads of Dianthus carthusianorum and Knautia macedonica emerge. The colouring-in has just begun. Return at this time of year, in late September or early October, and you will be mesmerised by the change of scene. It is as if a dozen Impressionists have been hard at work in the interim, artfully daubing it with the sunshine yellows of rudbeckia and silphium; the purples, sky-blues and lavender-blues of asters; the purple-red tri-lobed leaves of Coreopsis tripteris, known as tall tickseed, and the grey of Eryngium yuccifolium. The effect is stunning. Grass paths that curve between the beds have become all but invisible – impassable in places – as the perennials reach for the sky, some having now peaked at close to three metres high, with their heads waving in the breeze. There is no staking to be done, no feeding and not even any weeding (at this stage, at least). The forest of perennials is so thick, there is no room left for interlopers and each plant obligingly supports its neighbours. The whole scene can just be enjoyed for what it is. Landscape designer Tom sowed the prairie in January 2010 and it has fared extremely well since, still earning its place in his farmland garden at The Barn near Watford, only a mile or two from the M1 and M25. It continues to be experimental and Tom has been pleased with the effect it creates, especially as it provides such a wealth of flower colour later in the year. “It was quite a challenge to get it established – we had to deal with an explosion of buttercups to start with – and only a year ago I paid two people to pull up excess asters for a whole week in the autumn, just to redress the balance of species, but overall it has been a great success.”
Tom relied upon James Hitchmough, professor of horticultural ecology at the University of Sheffield, who worked on the wonderful planting schemes at London’s Olympic Park, to come up with tailor-made seed mixes. These suit the various soils found on the site, which are mostly sandy and free-draining but with an area of heavy clay at the eastern end. He used a combination of more than 50 species of tough perennials in a relatively high sowing density of between 96 and 130 seedlings per square metre.
Tom’s gardener Brian Maslin describes how it was made: “The land, previously meadow grassland and surrounded by hedges, was sprayed off, turned over with a digger and levelled.” Tom had designed a series of sinuous organic shapes, separated by two-metre-wide grass paths and a gravel walkway along the side nearest the house. “Once these were marked out, we loaded each one up with 75mm of sand to discourage weeds
“It is as if half a dozen Impressionists have been daubing with sunshine yellows and lavender blues”
and make a free-draining seedbed, then scattered the seed over each area by hand.” The seed had been weighed out and bagged up individually for each of the different areas and then mixed with large quantities of sawdust so that it could be more evenly distributed. “Of course, it was vital that it was done on a windless day,” Brian adds.
After seeding, jute matting was spread over the beds and pinned in place, to prevent the seed blowing away and to discourage birds. Over time, this has rotted down and disappeared but it provided useful protection initially. One of the joys (and, perhaps, sometimes one of the frustrations) of this method of garden-making is the randomness of it. “There is no control over the clumps,” Brian says. “They come up where they come up.”
An enormous amount of weeding had to be done in the first year to get on top of invaders such as buttercups and couch grass. Similar prairie gardens (including the one at RHS Garden Wisley) have not been such a great success, which Tom puts down to the sheer challenge of weed management. Even now, seven years on, spring weeding has to be assiduous from February until the beginning of June. “After that we can’t get into the beds because everything has grown together, which helps crowd the weeds out,” Brian says. “So we just pull out anything we can reach from the paths.” Once established,
the prairie garden pretty much looks after itself from early June until the end of January, when it is all cut down and either composted or burnt. Before that, in early winter it is alive with flocks of goldfinches, all vying for the thousands of seedheads that provide them with winter sustenance – a spectacle that Tom and his wife Sue take great delight in. It is a magical place for several months, changing day by day.
As the prairie has developed, species come and go at will. Veronicastrums have started to seed into it from adjoining areas of garden. Viola sororia has found its way here, which Tom is very happy about. He has added dieramas (Angel’s fishing rods) and latterly some purple sedums and goldenrod
Solidago rugosa, both of which he feels less sure about. For anyone contemplating sowing a similar prairie garden, Tom advises that an area of at least 200 square metres is needed and he feels that a boundary – either a hedge or a wall – is essential to contain and make sense of the planting. Of course, the species he has chosen can still be used in much smaller gardens in more conservative quantities, among mixed planting, to brighten the space in late summer and autumn. Asters (which are now renamed Symphyotrichum) are tough and reliable, and rudbeckia bring a burst of late-summer sunshine, while eryngiums provide long-lasting seedheads to punctuate the borders.
The prairie garden has been one of Tom’s test beds. “I felt I had to try it for myself. I design gardens for other people but with this concept I wanted to own it, manage it and watch how it behaves. That’s the way to learn.”
ABOVE New England aster ‘Septemberrubin’ and seedheads of Echinacea pallida are an attractive pairing OPPOSITE Therich yellow of Rudbeckia fulgida var. deamii contrasts with the aromatic aster Symphyotrichum oblongifolius
CLOCKWISE, FROM LEFT The architectural splendour ofEryngium yuccifolium with skyblue aster Symphyotrichumazureus and ruby S. novaeangliae ‘Septemberrubin’; sunny Rudbeckia fulgida var. deamii; Silphium terebinthinaceum
ABOVE The leaves of the yellow daisy-like Coreopsistripteris turn a deep purplered in autumn. It thrives in full sun BELOW The striking dark brown seedheads ofRudbeckia maxima stand out in low light