The RHS expects one-million visitors a year at Bridgewater and already gets one-million at Wisley. It sees Bridgewater as a way to tap into a northern market where it has little presence and believes Wisley can be even more popular and useful than it is now if the site is developed.
Landscape architects are now in place to work on the gardens - Tom Stuart-Smith (Bridgewater) and Christopher Bradley-Hole (Wisley). Stuart-Smith redesigned the Italian garden with contemporary perennial planting in an historic framework at Trentham a decade ago. But he said he has a lot more scope at Bridgewater because there is so little left at the derelict 19th century garden compared to all the archaeological structures that were at Trentham.
"There's quite a lot left in the woodland garden," he added. "Though it is not of huge variety there are some very good trees, but there's very little left in the walled garden so one has very little constraint with what one does with planting. The bigger area of debate is that relation to precedent and history, and the Nesfield Terraces and to what extent one works with historic precedent there.
"There might be some desire from some people to put it back, as it were. I suspect the RHS is not in the business of doing English Heritage restorations. That would be neither appropriate nor sustainable. These gardens are highly managed and maintained in a way that we couldn't hope to do now and wouldn't be talking to RHS members in a way that is relevant to the way they garden today. Finding a line between restoration and a contemporary garden is going to be very interesting." He said the 4ha walled garden will give him full rein on what can be achieved in such a space, with it being "much too big" for just fruit and vegetable growing. Overall, Stuart-Smith wants the site to be "relevant". More tree removal is ongoing at Bridgewater. There is an arboretum planned and catering, retail and visitor services are certain to be finished by 2019.
Bradley-Hole will work on a garden around the planned Wisley Hilltop new science and education centre, but his footprint will be most obvious at the entrance, where the shops between the car park and the 1916 Laboratory arts and crafts building are to be replaced by landscaping. Garden History Society president Dominic Cole said the job is "a jigsaw masterplanning exercise" that Bradley-Hole will excel at because "he is a thoughtful and clever designer who is good with hard surfaces, which is what they need with the footfall."
Visitor flow and telling horticultural stories will be a focus, though Bradley-Hole's use of plants will "shake up" the garden as much as any structural redesign. He said: "The two capital projects are catalysts for giving Wisley a new context."
A new building from architects Carmody Groake will be at the entrance. The architects were to renovate RHS Lindley Library in Westminster but that plan is on hold.
Bradley-Hole, who will be on site in 2016, said visitors enter Wisley by a "circuitous route at an awkward place" and his new approach will give visitors a new experience. While he is "very fond" of Wisley and aware that many say it is their favourite garden, the whole site has developed "piecemeal" and does not flow as well as it can. He said he does not believe there are any restrictions in place on designs, though "it's good to have a historical context - it will make the scheme richer, though it doesn't mean it will be backward-looking at all".
Revamps: Garden experts look ahead to key priorities for work
Garden Museum director Christopher Woodward has said retaining a feel of the Victorian/Edwardian garden is more important than a slavish reconstruction. "The main thing is what Tim Smit showed at the Lost Gardens of Heligan — what excited people at the time the garden was made," he explained.
"At Heligan it was the moment when the seed catalogue arrived with the head gardener to see the new varieties available." He said the restoration of Hampton Court gardens in the 1980s "showed how much you can deliver into a garden thought to have disappeared by using archaeology. But some gardens are scrupulously restored without any life in them."
The Gardens Trust president Dominic Cole has welcomed the appointment of the designers and said Bridgewater has been an important but overgrown garden, like the Lost Gardens of Heligan. His experience at Heligan tells him that there will be good-quality soil under what he calls the "scribble" of scrub. He added that a restoration "is a really simple job using the historical plans and analysis of what was there," but the designer "will want to import the present day".