To exhibit at an RHS show requires nerves of steel. For the nurseries and garden designers at this year’s Spring Flower Show in Cardiff the unusually mild winter has propelled many plants into early flowering. As if she’s preparing for a marathon, Linda Kelway has spent the run-up to the show shifting her collection of peonies around her nursery, from shelter and warmth to cooler spots and back again, to try to get them into peak condition.

“Normally we move the plants out of the greenhouse in February, but this year they were so advanced it was December,” she explains. Even with a spell of ten days of refrigeration, many of the glorious blooms on her display were already shedding petals the day before judging. Those she could rescue, she had tied shut with string.

For Thomson & Morgan, the seed supplier, the last-minute problem was one of vandalism and theft. When Arthur Davies and his team entered the pavilion on Thursday to put the finishing touches to their display of vegetables they found that a squirrel had dragged down a basket of chili peppers and scattered them with gay abandon along the ground. This was clearly a squirrel with exotic tastes, as it bypassed a truss of polished Tomato Tomazing, one of the sweetest varieties on the market, on its climb up to the finger-sized “Heatwave” fruits. Or, suggested Davies, it was in fact a truly gourmet rodent and ignored the tomatoes because it knew that they had been grown out of season and so wouldn’t taste as good.

The earliest and youngest of the RHS’s major shows — this is Cardiff’s third year — also has the youngest participation. Competing for the best planted wheelbarrow are several hundred children from nursery and primary schools in the city. Their efforts are a celebration of the inventiveness of children and of how plants can fire their imaginations. One group wanted to make a sheep and so constructed a papier-mâché head, black plastic legs and mounded white daisies and violas, with twists of white plastic, for the body. There’s a prehistoric landscape of ivies and grasses, complete with plastic dinosaurs; a sand-filled barrow dotted with golden Viola cornuta and signs reminding us to be water conscious; and one mounded high with a cornucopia of vegetables and herbs.

A few steps away from the barrows is a model allotment set up to show the various stages of vegetable growing, from seedlings and chitted potatoes in raised beds, to salads, beetroots and carrots making a colourful display in 3ft-square plastic planters (ideal for tiny gardens or balconies). Members of the Welsh branch of the National Vegetable Society are on hand to demystify growing techniques.

More esoteric edibles make an appearance in the Ambrosial Forest show garden designed by Anthea Guthrie, who is also making gardens for Chelsea and Hampton Court. Using mossy logs from the fields around her home in Glamorgan, and fruitful trees such as hazel, crab apple, medlar and quince, she has created a tranquil semi-woodland scene where you could graze on various berries, leaves and petals at different times of the year.

The coastline at Lavernock and Southerdown has inspired the designer Christine Wilson to make a small contemporary garden for a young couple, complete with a grassy bed, aromatic plants creeping through sandstone paving, and a vertical water feature that mirrors the red clay cliffs .

Unlike Chelsea, where the show gardens dominate, Cardiff is more of a pick-and-mix experience, all on a small and manageable scale.

In the spacious pavilions many of the nurseries that exhibit in the other major shows can be found, but also some local growers such as Pembrokeshire Plants. These may not have the impeccable presentation of the old hands, but what they offer is a fresh palette of plants, as in Patrick Macnaghten’s eclectic mix of unusual but hardy species, such as Acacia longifolia, Geranium palmatum and the evergreen shrub Polygala x dalmaisiana that produces its butterfly-shaped cerise flowers right through the year in his garden. There is also a marquee filled with an array of Welsh foods, from cheeses to chutneys, and crafts.

Cardiff is definitely a family-friendly show — it’s just a short walk from the station and children under 16 are free — and afterwards there are the grassy expanses of Bute Park to play or picnic in.

RHS Spring Flower Show,

Bute Park, Cardiff, today 10am-5.30pm, tomorrow 10am-4.30pm (sell-off 4pm). £10, children under 16 free. www.rhs.org.uk/cardiff

Book now: Malvern Spring Gardening Show, May 10-13 www.threecounties.co.uk,

01684 584-924

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