Urban gardener: Realm of the senses

Last summer I got a call from Bupa asking if I'd design a garden for them at this year's Chelsea Flower Show. The aim would be to highlight their work in the care-home sector, especially their work for people with dementia or Parkinson's disease. While I was delighted to be asked, it was touch and go as to whether I could oblige. A viral infection (a parting gift from a trip to Nepal) had knocked me for six and, with creativity in the doldrums, meeting the RHS deadline for submissions seemed unlikely. Fortunately, a lucid moment kick-started just enough imagination to meet the brief – to create a sensory garden to emphasise Bupa's promise ("caring for you as an individual"). The garden would then relocate to a real care home after the show.

I'm sure I'm not the only designer who shudders every time "sensory garden" is mentioned, but it really wasn't fair to say it to someone already running a fever. Every garden ever created has some sort of sensory credential and of course they are invaluable in care homes, especially for people with dementia where even the most fleeting recollection might be enough to carry someone through the day. But such gardens almost inevitably carry the risk of garden indigestion, where too many elements vie for attention – making both the space and the experience feel muddled and disjointed. Looking back, I'm wondering whether my malady might have worked to my advantage as, like a Method actor, I was able to use my temporary infirmity to understand exactly what one might want from a garden during a low ebb.

I'm making this sound a lot more dramatic than it actually was, but on the odd occasion I felt well enough to sit outside, it brought home the power of green space, not necessarily in terms of physical healing but simple comfort. In good health I am occasionally inclined to feel anxious about things that need attention in the garden, but illness cuts through to what really matters. Sun on skin, a gentle breeze, foliage and birdsong. The shifting sounds and scents of my verdant sanctuary served to lift my spirits. Here was a place to breathe, relax, and feel safe.

Of course the Bupa garden will have most of the raw ingredients you might expect in a sensory garden: colour, scent, texture, the sound of running water and a powerful sculpture to add a touch of drama and wonder. But what about taste? While there will be amelanchier berries to pick later in the season or mint and lemon verbena to make tea with, I've resisted the temptation to include a space to grow vegetables. The garden might be altered slightly to suit the specific needs of the care home it ends up in, and this may well include space for food to encourage a more hands-on approach, but the danger in a show garden is paying lip service to everything and, in doing so, weakening its overall impression. A raised bed will also feature, allowing those in wheelchairs more intimacy with plants, but even this, as practical as it might be, can kill a space if not handled correctly.

But for all that, movement through the space will be one of the most important elements. Surfaces have to be non-slip and level. Dementia causes confusion so paths should not change colour or pattern too often, as they may cause insecurity and impede movement. Dead-ends, too, can be unnerving, which is why the most effective designs are derived from the figure eight. The design for Bupa has metamorphosed from this number into a network of paths to and around a large sculpted sphere. With a diameter of 2.2m (just over 7ft) the giant boule is dominant yet serene and conveniently symbolic of Bupa's global values. Whether these ingredients will be enough to capture the invisible but all-important sense of place among the bustle of Chelsea, only time will tell. If it's dramatic enough to tempt entry and carries enough charm to make people linger I'll be happy. Who knows, along the way, we may even come up with another name for sensory garden.