But they have also warned there are several barriers to that happening, including lack of plant knowledge among designers and the challenge for growers of supplying a wide and unpredictable range of plants.
Dr Nigel Dunnett, professor of planting design at the University of Sheffield, has in Horticulture Week called on designers to apply the principles of the "new perennial" style of planting to their shrubs (HW, 15 April). These "new shrubanistas" could take inspiration from the way plants grow in the wild, planting in less rigid groups and encouraging a more ecological approach to shrub and small-tree planting.
Certainly shrubs offer a better range, effect, all-year-round appeal, flower colour and scent than any other group or planting "movement", according to Coles Nurseries key account manager Vince Edwards. These aspects should appeal to designers and specifiers who must deliver plants that fit the design brief while also offering value for money.
"The beauty of the shrub is that it can be used as the structure and focus of the design while also allowing for herbaceous and grasses to add a seasonal lift," he said. But shrubs are often "victims of their own success" because they come to dominate the plantings, he added.
"In order to promote and ensure we utilise the vast numbers of shrubs available, perhaps we need to look towards the maintenance and skills required to keep the shrubs in balance with the rest of the scheme, while allowing for seasonal lifts from other partners. Management is the key to bringing the shrub back to the forefront of any design. The selection and use of the shrubs needs to also reflect the theme, location and appearance of the finished area."
Edwards added that designers must be careful that the "natural look" doesn't become "something that the wider public confuse with scruffy, one-dimensional and out of place".
Boningale Nurseries chairman Tim Edwards said herbaceous plants put on a great show but shrubs give a design height and depth as well as adding different microclimates. "There has been a move away from vast use of a small number of shrubs - think cotoneaster - and I think moving away from that was a good thing. I'm just not entirely comfortable that we've moved so convincingly to herbaceous plants."
That is partly because the range of herbaceous plants requested of nurseries is vast and unpredictable, with designers constantly finding new sources of inspiration - the palette has not stabilised over time. This makes it "exceedingly difficult" to satisfy demand, he said.
On the other hand, "when they think of shrubs they refer to a limited number of well-known books and the list of shrubs doesn't expand as quickly as that of perennials, and so we produce shrubs in line with that".
Many designers may have been taking their cues from garden centres that fill small planterias with high-turnover plants that are at their peak. "This approach sells more plants but leaves little room for shrubs, which might provide a garden's framework but rarely look as impressive as a herbaceous plant at it's most exotic, so don't do so well on impulse," said Edwards. "I think many designers have been swept up with this approach and have overlooked shrubs as they see garden centres concentrate on herbaceous ranges."
The frustration with landscape architects' lack of plant education is also a theme. Edwards said: "You do find some who know about plants, but most will admit they are taught very little about plants throughout their training. Those that do understand plants have usually learned what they know elsewhere." That situation would need to improve before most designers could really use a wide range of shrubs to good effect, or at a minimum they could be provided with some sort of design palettes. That would also direct designers to a standard range that growers could produce with some reliability, he added.
Hillier Nurseries commercial division director Hossein Arshadi said he also wants more shrubs to be used, particularly in big jobs and commercial areas where there is adequate space. But it would have to be subject to each site's unique challenges and they must be allowed to "do their thing", unlike former years that saw many shrubs treated as glorified hedges.
Arshadi said he does not want to see the pendulum swing back to shrubs and away from perennials but a mix of both. "Generally speaking a larger project with big spacing needs to mix medium to large shrubs and small trees, like amelanchier, cercis, viburnums and pines, with more perennials and grasses," he explained. "That type of plant will give structure and height and the others could do their thing later on."
While some designers follow this approach, too many use just grasses and herbaceous, partly out of a fear of shrubs growing too big and becoming messy. However, perennials can also leave a mess, as Dunnett highlighted. "I definitely agree with where Nigel is coming from," said Arshadi. "Where the space allows, you need to plant larger structural plants and let them do their own thing and grow in their natural shape. Say Viburnum plicatum - that needs to be left alone to do its own thing rather than being clipped and butchered. So it is horses for courses.
"There are some public sites that use very high-quality granite paving with large trees and street furniture and very little else, and it looks lovely and smart. You don't need a lot of shrubs or herbaceous to mess it up. But in other areas there are residents who need a bit of colour. In public parks and walkways they need more than trees, but then whoever manages these sites needs to have the budgets to maintain them."
Arshadi added that there are "some fantastic, very talented designers, and the knowledge is there, but I think maybe the restriction comes from the site, budgets and the space".
Landscape designer Janine Pattison agreed that shrubs are long overdue for a reappraisal. But Pattison, who has a background as a professional gardener, warned that shrubs require much more skill to work with successfully.
"Perennials and grasses are very forgiving. They will cope with poorer soil preparation, can be planted in high-density and still perform well. They need little care during the growing season and most can be simply chopped back in the autumn/winter," she said. "It takes skill to design with them well, but they can be maintained with less skill. They are high-impact from the first year. They are very economical."
Shrubs, on the other hand, require good knowledge of growth rates for spacing, better soil preparation and patience, and additional weeding while they establish. "Pruning requires skill to avoid the 'blob chop' favoured by most maintenance contractors," said Pattison. "Pruning needs to be done at the right time of year to allow flowering. If camellias are pruned in the autumn, all the spring buds will be lost."
Modern gardens are often too small for most shrubs and the upfront cost is high for good-quality shrubs, she added. "But they provide vital structure and interest in a garden. We always use a proportion of evergreen shrubs - hebes are a favourite as well as Laurus and Taxus."
Shrub expert and former Hillier managing director Andy McIndoe said much of the focus on perennials, particularly in garden centres, is because they are cheap and quick to produce. But he said the move away from shrubs has not really happened in domestic gardens - only in the landscape design world.
"You know when you go to Chelseas that they will be crammed with bearded irises, black cow parsley, alliums - it's always the same. It's what's ready at this time of year. There are no middle layers in show gardens, unless it's a bloody mirror."
However, the general public are still shrub enthuasiasts, he added. "What actual designers are doing has remarkably little influence (on the public) although they might think otherwise. If you're talking about the popularity of shrubs (some are) phenomenal, like hydrangeas. There are new introductions all the time."