Gardening: The seed of an idea on the verge . . . . . . to be sown at home: Anna Pavord admires the grasses and flowers on a chalkland bypass and explains how you can adopt the technique

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Bringing the good news from Ghent to Aix must have been a doddle compared with trying to compliment our local roads department. I wanted to thank someone for the verges, particularly on the new cutting of the bypass west of Dorchester in Dorset. In spring, its chalk slopes were thick with cowslips. Now there are ox-eye daisies, scabious, lady's bedstraw and vetch.

I had to call seven different offices before I found Derek Fowler, a civil engineer, who with extreme caution said that, yes, he had something to do with the verges in question. It helped, he said, that the cutting had been made through chalk. The rich topsoil had been removed, leaving subsoil that had been buried deeply enough to be free of the seeds of nettle, dock and other rampant weeds. Such seeds in rich soil most often scupper attempts to make wild-flower gardens.

Road engineers, he explains, need cover to prevent erosion of their verge slopes. For years, the standard Department of Transport mix for verge seeding has consisted of lush types of grass spiced with clover. The resulting sward needs frequent mowing and provides impossible competition for most wild flowers.

The county ecologist developed a mix using low-growing, unaggressive grasses to stabilise the slopes - grasses that co-exist with wild flowers on chalk downland, where flowers are followed by butterflies and grasshoppers, small mammals and birds, each group attacking the next in the way that pleases environmentalists.

'Why the change of heart?' I asked Mr Fowler. He shrugged, unable to pinpoint the moment verges began to be seen as an asset rather than a necessary evil of road building. Seeding with wild flowers is scarcely more expensive than other treatments; it cost only pounds 2,000 out of the pounds 2m bypass budget.

The idea is catching on, even along the trunk roads and motorways within the DoT's remit. I concentrate too much on staying alive on the M25 to notice wild flowers there, but they certainly flourish on the M32 north of Bristol. The DoT used a slightly different technique there; of the 30,000 wild-flower plants introduced, ox-eye daisy, of course, does well, but you will also see cranesbill, musk mallow, ragged robin, knapweed and sainfoin.

The plants were raised from seed by High Value Horticulture of Uxbridge. The DoT is still monitoring its M32 planting, but already common blue, large skipper, marbled white and meadow brown butterflies have been seen along the verges. Now I am waiting for green- winged orchids on the M1.

To grow a wild-flower sward on dry chalk soil start with a grass mix made up of roughly equal quantities of three fescues. The following make a good base. Festuca rubra subsp. rubra (creeping fescue) has low-growing, narrow leaves and flowers in May and June on long, erect spikelets. It is common in meadows, hedgebanks, dry grasslands and dunes. Festuca rubra subsp. commutata is similar, but without rhizomes. It is now extremely common on dry soils, downs and road sides. Festuca ovina (sheep's fescue) has narrow, inrolled leaves and rarely grows taller than eight inches. It is common on heaths and moors where it flowers between May and July.

To this base add smaller quantities of the two grasses below, using one third of the measure you have used for the fescues. Anthoxanthum odoratum (scented vernal grass) has a compact, flowering spike of two to three inches on an unbranched stem. It flowers from April to June and is abundant everywhere. Cynosorus cristatus (crested dog's tail) grows one or two feet high and has pointed leaves and an upright flower spike arranged in a series of regular whorls. It flowers between June and August in meadows and grassland.

Add a final seasoning of the following two grasses, with half the measure used for the vernal grass and the dog's tail. Briza media (common quaking grass) has light, airy flower spikes and a series of small, woven lockets dangling on thread-like stems. It flowers between June and August on dry grassland, especially on chalk. Trisetum flavescens (yellow oat grass) grows to one or two feet and has flat, pointed leaves and broad, feathery heads of pale-yellow flowers between June and July.

Then add a selection of native wild flowers to the grass mix. The ones I suggest all have a fighting chance of germinating from seed which can be mixed with the grass seed and sown at the same time. Aggressive species such as the ox- eye daisy are best left out and sown separately in patches.

Betonica officinalis (betony): grows to about a foot and has dense heads of lippy, red-purple flowers June-Sept. Campanula glomerata (clustered bell flower): deep-blue bells at the end of 6-8in stems, May-Sept. Campanula rotundifolia (harebell): lighter and airier, with a bigger, bell flowers, July-Sept. Conopodium majus (pignut): feathery leaved umbellifer and flat, broad heads of white flowers flourishing in shade, May-June. Galium verum (lady's bedstraw): grows to 18ins, with narrow leaves in whorls around the stem. Plumes of tiny yellow flowers July-Sept. Helianthemum nummularium (rock rose): a low, spreading sub-shrub with showy yellow flowers July-Sept. Leontodon hispidus (rough hawkbit): hairy stems carry yellow dandelion-like flowers Jun-Sep. Leucanthemum vulgare (tansy): flowers appear as yellow buttons on top of two-foot stems with aromatic leaves. Common on hedge banks, Jul-Sep. Lotus corniculatus (bird's foot trefoil): creeping trefoil leaves topped by bright-yellow bonnetted flowers on five-inch stems, Jun-Aug. Plantago media (hoary plantain): wide, ground- hugging leaves and a bottle-brush flower of greyish white, Jun-Sep. Primula veris (cowslip): heads of bright-yellow flowers like bunches of small primroses, Apr-May. Poterium sanguisorba (salad burnet): round, purple flower heads on foot-tall stems, the leaves small and sparse, common on dry chalk pasture, May-Aug. Ranunculus bulbosus (bulbous buttercup): fine leaved buttercup growing from a bulbous root common in dry pastures, May-Jul. Scabiosa columbaria (scabious): wiry two- foot stems topped with large greyish blue flowers, Jul-Aug. Succisa pratensis (devil's bit scabious): the 18-inch stem is topped with rounded flowers of typical scabious blue, favours slightly damper ground than the true scabious, June-Sep.

All these have a fighting chance of germinating from seed which can be mixed in with the grass seed and sown at the same time. Aggressive species such as the ox eye daisy are best left out of the overall mix and sown separately in patches. Betonica officinalis (betony) Growing to about a foot and flowering with dense heads of lippy red-purple flowers, Jun-Sep. Campanula glomerata (clustered bell flower) Deep blue bells at the end of 6-8in stems, May-Sep. Campanula rotundifolia (harebell) Lighter, airier than the above with a bigger, more generous blue bell flower. Grows to one foot, Jul-Sep. Conopodium majus (pignut) Feathery leaved umbellifer with flat broad heads of white flowers flourishing in shade, May-Jun. Galium verum (lady's bedstraw) Grows to 18ins with small narrow leaves arranged in whorls around the stem. Plumes of tiny yellow flowers, Jul-Sep. Helianthemum nummularium (rock rose) Low, spreading sub-shrub with showy yellow flowers, an inch across, Jul- Sep. Leontodon hispidus (rough hawkbit) Hairy stems carry yellow dandelion-like flowers, drooping in bud. Common on chalky soils, Jun-Sep. Leucanthemum vulgare (tansy) Flowers appear as yellow buttons on top of two foot stems with aromatic leaves. Common on hedge banks, Jul-Sep. Lotus corniculatus (bird's foot trefoil) Creeping trefoil leaves topped by bright yellow bonnetted flowers on five inch stems, Jun-Aug. Plantago media (hoary plantain) Wide ground hugging leaves from which springs a strong stalk topped by a bottle brush flower of greyish white, Jun-Sep. Primula veris (cowslip) Heads of bright yellow flowers like bunches of small primroses, Apr-May. Poterium sanguisorba (salad burnet) Round purple flower heads on foot-tall stems, the leaves small and sparse, common on dry chalk pasture, May-Aug. Ranunculus bulbosus (bulbous buttercup) Fine leaved buttercup growing from a bulbous root common in dry pastures, May-Jul. Scabiosa columbaria (scabious) Wiry two foot stems topped with large greyish blue flowers, wider petalled than the devil's bit scabious, Jul-Aug. Succisa pratensis (devil's bit scabious) The 18 inch stem is topped with rounded flowers of typical scabious blue, favours slightly damper ground than the true scabious, June-Sep. Wild flower seed and plants available from Kingsfield Conservation Nursery, Broadenham Lane, Winsham, Chard, Somerset TA20 4JF (Tel: 0460 30070), The Wild Flower Centre, Church Farm, Sisland, Loddon, Norwich, Norfolk NR14 6EF (Tel: 0508 520235), Hewthorn Herbs and Wild Flowers, Simkins Farm, Adbolton Lane, West Bridgford, Nottingham NG2 5AS (Tel: 0602 812861).

(Photograph omitted)

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