Urban Gardener: Calm before the storm

If adrenaline had a smell, you'd get a mighty whiff of it in the grounds of the Royal Hospital this weekend. Exhibitors at this year's Chelsea Flower Show depend on it for the next 48 hours as almost a year's planning reaches its zenith. At the Bupa Garden, we have until 8am on Monday morning to nip, tuck and titivate before the Royal Horticultural Society judges don their serious faces, examine their notes and pick any holes they can find before awarding the appropriate medals. Most exhibitors aim to finish their garden by close of play today. This will allow plants to settle and look all the more natural, rather than a scruffy, stuffed appearance that betrays nothing but panic. If the weather is kind in the final three weeks then a few might achieve this, but the reality is that most will work until the last possible moment – lest the rim of a pot, a faded bloom or leaking pond lose them vital points and the chance of a decent medal.

On paper, the Bupa Garden looks like a fairly straightforward affair (a path through planting to a large sculpted boulle, with several pausing opportunities along the way), but it has turned out to be quite a challenge. The garden will be re-located to Meadbank Care Home in Battersea, south London, after the show, where many residents have either Alzheimer's or Parkinson's disease, so experts at Bupa have been careful to point out certain restrictions. No steps or slopes for a start. Surfaces must also be non-slip and allow safe movement for residents, some of whom will be in wheelchairs. Dead-ends can cause confusion, as does varying types of paving material. An early idea to have polished decorative plaques on the boundary wall was vetoed because catching sight of your own reflection walking towards you can be disturbing for anyone with dementia. But for all this the garden has to be a sensory experience.

All gardens have some sensory value, so the biggest challenge has been trying to deal with all the baggage that comes with the term "sensory" (think brutal raised beds and wind chimes), without it becoming a slave to the stereotype. A well-designed garden should be able to stand on its own two feet without water, scent or even sound and excessive colour. Few, including me, would be brave enough to explore this angle at an event so prestigious, but my aim is to exercise just a little self-restraint (just one raised bed and no wind chimes). Instead of a check-list of sensory clichés, my hope is that a strong sense of place will be enough to improve one's well-being. For while the sight and scent of a rose might be a potent memory trigger, an abiding sense that the garden is a pleasant space to ponder or seek solace – long after the rose has faded – is ultimately more important.

Mary Keen sums it up beautifully in "Gardens as Theatre", a chapter in the BBC book Gardens of Inspiration: "The real point is the place and what it does to you as a person and how, having drained and smoothed the mind, so that all the worries evaporate, it leaves you free to walk or sit so that your head can be filled with something calmer than the trivia which we all collect in our brains ... such gardens have no rival. Imagine shade when you are hot, and space when you feel crowded; add to that a sense that nothing else matters except what is here and now, that time has stopped, and all is well with the world and will be so forever."

The chapter has become my Holy Grail. I don't honestly know if I've reached it yet in a real garden and of course it will be impossible to find it in a show garden that hasn't had the time to develop. But if there's one part of the Bupa Garden that can momentarily diffuse the cacophony of crowds, cameras or public address systems, and provide a small window of dream-time, I'll know that even if it doesn't win the medal we all secretly desire, it will certainly be well-equipped to develop and fulfil an altogether more important quest.