It was heralded as the “credit-crunch Chelsea” — several big show-garden sponsors had dropped out and, late in the day, the RHS invited Sarah Eberle, the 2007 Best in Show winner, to design three low-budget front gardens — but a stroll down Main Avenue at this year’s flower show reveals that the business of creating innovative, exuberant and inspiring gardens is alive and well.

The urban gardens, which for the first time are intermingled with the main show gardens, have gained two metres — they now measure 7x5m. This has given the designers more scope to make real-size gardens rather than mini-versions of larger ones.

Several designers across all the categories have opted for styles of gardens that visitors could easily re-create themselves. The QVC Garden by Adam Frost has a central seating area with a fire pit and raised herb bed surrounded by romantic planting and flowing water. The four front gardens designed by Ian Dexter for the Marshalls Living Street combine practical considerations — car parking, water collection, storage, composting — with generous planting. Mark Gregory’s elegant urban garden for the Children’s Society includes such backgarden necessities as a washing line (his rectractable model is ingeniously housed in the framework of the garden room).

Two hotly tipped gardens for Best in Show, Ulf Nordfjell’s design for The Daily Telegraph and Luciano Giubbilei’s Laurent Perrier Garden, are aspirational in their scale and structures. Giubbilei’s tiers of clipped yew and box and an allée of pleached hornbeams enclose squares of exquisite tapestry planting using peonies, astrantias, salvias, irises and bronze fennel.

Nordfjell’s contemporary black-framed garden room looks on to several areas of tightly controlled planting that offer delightful combinations such as harebells floating above the silver-leaved Antennaria dioica and cushions of Festuca gautieri.

The more specialised gardens include Tom Hoblyn’s Foreign and Colonial Investments’ Garden, which celebrates the fragile bogs of Carolina and pairs endangered plants such as the lime-green Sarracenia flava with British moisture-lovers such as the inky Iris ‘Dorothy Robinson’ and dark-green Cooper’s rush.

For those who prefer edgy designs Tony Smith’s Quilted Velvet Garden is an unsettling juxtaposition of pink busy lizzies, grey slate and spiky yuccas, palms and cordylines, while the Canary Islands Spa Garden relies on the texture and shapes of the green exotics — no colourful flowers here — to offset the expanses of black stone.

Among the small gardens Nick Dexter’s contemporary design for Witan Investment Trust introduces the idea of having your own rushing brook in the back garden which you can look down on while stretched out on your concrete recliner on a glass deck.

Many of the designers have returned to recent Chelsea favourites for their plant palettes, including Cornus kausa, multi-stemmed birches and swathes of irises, aquilegias (especially the claret coloured ‘Ruby Port’), alliums, astrantias and foxgloves. Ian Dexter chose Angelica gigas as a unifying element in his four gardens, and its architectural form appears in several of the other show gardens. It is used to great effect in the Great Pavilion too, in Jekka McVicar’s vibrant display of medicinal herbs which includes orange calendulas and nasturtiums, bright-yellow woad, golden gorse, red field poppies, mauve thymes and lavenders. Planted a safe distance back from the passing crowds is a clump of innocent-looking brown and green bell-shaped flowers. This turns out to be Belladonna atropa belladonna, famed for the toxicity of its berries but whose roots and leaves are used by herbalists, and here making its Chelsea debut.

Other newcomers to look out for include the smart white dahlia with brown foliage named for Joe Swift from the National Dahlia Collection, Geranium phaeum ‘Mottisfont Rose’ with dark-pink edges and a white centre from the Hardy Plant Society, and four roses from David Austin including the cluster-flowering white ‘Kew’ which the grower Michael Marriott describes as “truly continuous”.

There is much spectacle in the Great Pavilion this year from cut flowers — exquisite arrangements from Jane Packer and Zita Elze, of the National Association of Flower Arrangement Societies, and vibrant displays from the West Indies using anthurias, strelitzias and heliconias.

A massed display of golden osteospermums and carpet bedding gerberas in red, yellow and orange is provided by the City of Durban, and there is a stunning re-creation of a coral reef from the Cayman Islands using euphorbias, succulents, ferns, grasses and sedges grown by Newington Nurseries to suggest the endangered corals.

There are also gloomy messages about global warming from Writtle College but it is hard to take them on board when just behind you is Downderry Nursery’s glorious spiral of lavenders and trellises smothered in perfect clematis from Thorncroft and Raymond Evison nurseries.

RHS Chelsea Flower Show runs until Saturday, May 23.