The garden inspector: Nun's Acre, Oxfordshire PROBLEM THREE How to make more of an under-used flat area INSPECTOR'S RECOMMENDATION Edge with boards and cover with grit for pétanque The most remarkable thing about Nun's Acre, a cul-de-sac of Seventies-built houses with neat and flowery front gardens on the edge of Goring-on-Thames in Oxfordshire, is its unremarkableness. Until I noticed the trees; a weeping beech dominates almost a whole garden, and the entire place has a backdrop of evergreen North American giants. Nun's Acre has a special secret: behind this ordinary collection of modern homes, and jointly owned by all its residents, there is a large tract of land. Some 98ft (30m) square, sloping down to the edge of the Thames, the spacious lawn traversed by broad gravel paths and with a diminishing population of elderly trees, is all that remains of the grounds of one of those dark, unmanageable Victorian houses that were demolished to make way for the 20th-century "boxes" (as one resident describes them). Chris, with husband Tim, neighbour Janet and other residents, has been managing this communal space for three decades. I wondered why they had called me in. After all, the place is kempt, attractive in a low-key way, with neat paths. It is mown by a contractor, and twice a year all residents help with maintenance blitzes. But these regular "Tuesday gardeners" wanted to make the space more "interesting" on a tight budget. However, closer questioning revealed little in the way of grand horticultural ambitions. The place has always been a social space - for dog-walking, boating and fishing, child exercising, that sort of thing. "Drinking," it turned out, is a favourite summer activity - tea in the afternoon, tipple of choice once the sun is over the yardarm and barbecues in clement weather. I spied several picnic tables cowering under the canopy of the mightiest "giant" (a western red cedar). These are brought out on to the grass in good weather. Great, I thought. I've got my work cut out. First thoughts Chris and I were in touch before my visit, and she had sent me a detailed history of Nun's Acre, with photographs of the house and garden in its heyday and in a later incarnation when it was owned by the Civil Service Motoring Club. Fresh from visiting a couple of restored National Trust gardens, I imagined that the residents might want to echo the spirit of the property's former glory. They had planted a mini-avenue of ornamental cherry trees close to the original entrance steps, to flank the path to the river's edge. I thought they might go for another "formal" touch - roses on ropes swagged across the river frontage in line with that main path, perhaps? These ideas fell on stony ground: winter flooding was a problem, I was told. I had to settle for encouraging them to extend the cherry avenue down the slope. The last thing on the minds of this hedonistic bunch was that I should encourage them to do any more gardening. In fact, I got the impression that they wouldn't mind doing considerably less. Tough love With more gardening and any restoration out of the question, I decided to take the group in hand. If all they wanted to do was sit around drinking and picnicking (that reads badly, but it isn't meant to), why not create a decent space in which to do it? Using the residents as props, I mapped out how they could extend the paths to make a people-friendly apron of gravel on the riverfront, perhaps edging it with flood-tolerant plants - red-stemmed cornus, bog irises, primulas. Some got the idea. Others were less sure about the work involved. I pressed on. Why was the only usable flat space blighted by the low canopy of the giant red cedar? Couldn't this make an easy-to-supervise children's play area? They replied that the local authority, to which they had to apply before undertaking any tree work, had forbidden them to raise the canopy of this, the biggest tree. This seemed totally unreasonable. I urged them to go back to the department armed with photographs (the canopy was farther from the ground in the old CSMC days) and try harder. A grand tour It was time we took a tour, to identify any labour-saving wheezes and provide the "fresh pair of eyes" that they were expecting. I liked the informal boundary hedge, consisting of shrub roses (R. pimpinellifolia and R. 'Hansa"), blackthorn and other natives that they had planted three years previously. The native hedging plants would probably outstrip the roses, so I encouraged them to plant more of them. Then ping! In idle discussion, the residents revealed that they would like more roses - specifically low-maintenance scented rugosas. We next came upon a lozenge-shaped flower bed where weeds threatened to gain the upper hand. We decided that it was worth gutting this, then recreating it as a larger crescent-shaped rose bed, making a pleasant picnic spot away from the river. Naturally thicket-forming, scented rugosa roses would sit well here, with the ground between them mulched with bark to keep weeds at bay. The only other flower bed, wrapped around the base of a tree, was well planted with spring flowers, ferns and hardy geraniums, and looked rather good. It could be expanded, I told them. Next we went to an area at the top corner of the garden, where a mass of snowberry was being grubbed out by hand and with Roundup. Chris asked for suggestions for this area, at the centre of which was an attractive charred stump. Seeing that perennial weeds were still in evidence, I suggested it was too soon to replant. An early-autumn treatment with Roundup would probably see off the last of them. With the coast clear next spring, they could plant a mixture of easy "old garden" shrubs - weigelas, philadelphus and big, berrying cotoneasters. Let's have a ball It was nearly time to leave, and I still felt that I needed to encourage these people to do something more in their wonderful space. Then it came to me. At the top of the sloping garden, the main path was flat. If they widened it, replaced the coarse surface with finer grit and edged it with boards, it would be ideal for pétanque. I borrowed the dog's ball and made everyone line up for the photographer for a game of "virtual pétanque." Try to look French, I said. Shrug, remove imaginary berets, point at invisible boules and look incredulous (that bit was easy). This time next year, I said, you'll all be at it. They smiled indulgently, rolled their eyes in an un-Gallic way and sloped back for tea. I reckon they might go for the pétanque, though. Tips and tricks For low-maintenance, albeit unsophisticated, rose beds, choose naturally suckering rugosa roses, for example R. rugosa 'Alba" and 'Rubra" (these hybrids are grafted and will not produce flowering suckers). Rugosa roses will be disease-free, thicken up like a hedge and can be simply pruned by half each spring. Deadhead initially, but leave later blooms to form hips for autumn. Mulch beds thickly to quash weed growth and cut down on maintenance. If perennial weeds defeat you in the summer, treat them with glyphosate (Roundup) in early autumn when their leaves are dying down. It should kill the roots before the following spring. John Lewis Boules Set, £8 (020 7629 7711). 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