Summer bedding is a British tradition that never quite falls out of favour, despite what trend-setters would have us believe. And no display is complete without petunias: generous, versatile plants with a long flowering season and easy-going nature.
Petunias originally come from South America, where they colonise poor, stony ground. They were brought to the UK by plant-hunters in the early 19th century and became part of a range of exotic half-hardy annuals used for complex - and expensive - bedding displays in Victorian parks and gardens.
Until recently, all petunias were seed-raised hybrids, probably crosses of P. axillaris and P. integrifolia. Since 1990, however, the introduction of vegetatively propagated strains has brought an explosion in the range of Petunia varieties. Cuttings-raised petunias, mainly bred for baskets and containers, make vigorous, free-branching plants. The Surfinia series featured some of the first cuttings-raised plants and still dominates the market, but its claim to be a true series is disputed because the brand name is attached to petunias with a wide variety of habits and flowers.
More uniform series include Tumbelina (double-flowered and trailing), Conchita (double, early-flowering) and Viva (large-flowered and trailing), with new variations coming out all the time. Breeders of cheaper seed-raised petunias have developed some equally good modern strains, and these are usually the preferred choice for bedding out in the garden, but superior promotion of cuttings-raised petunias has largely overshadowed them in the market.
The wide choice and the frequency with which new series are released have made petunias something of a victim of their own success. It is revealing that, of two RHS trials in 2002 and 2005, many varieties awarded the Award of Garden Merit are no longer easy to find. There is also confusion over the reclassification of some as Calibrachoa - C. Million Bells series, for example, is often mis-sold as Petunia.
Petunias are consistent sellers and it is not hard to find reasons for their enduring popularity. They flower from May to October and suffer few pests and diseases. Even the threat of tobacco mosaic virus - once a major scourge - has receded since an outbreak in the early 1990s led to a tightening of plant quality control. The continuing risk of virus, however, makes it essential to start with fresh stock each year.
Regular feeding, deadheading and cutting back leggy plants to encourage bushiness is all the maintenance that is required. Many larger-flowered varieties don't stand up to bad weather because their blossoms are damaged in heavy rainfall - but modern strains are breeding this negative tendency out.
WHAT THE SPECIALISTS SAY
- David Kerley, owner, DW & PG Kerley, Cambridgeshire
"'Series' is a bit of a problematic term: we try to breed series where plants are matched for earliness, habits and so on. One of the most famous series, Surfinia, isn't really a series at all - it's lots of different plants with the name Surfinia attached. It's a very good brand name, but the plants are not associated.
"We bred the world's first double Petunia with a hanging habit - 'Priscilla', the first of the Tumbelina series. It was introduced in 1997 and we've had demand from around the world. It's still probably our best variety. It's certainly our biggest seller. I do very much like the new Ripples, too - they're bicoloured and look stunning.
"Petunias are susceptible to infection, especially tobacco mosaic virus, which spreads very quickly. You have to start with clean stock every year.
"They like lots of sun - the flowers are damaged by heavy rain. Hanging baskets and tubs are what we breed for - we do plant them in the border but they look best in containers."
- Simon Crawford, product development manager, Young Plants, Warwickshire
"In the cuttings-raised sector Young Plants has stuck with Surfinia, primarily because the brand is so strong that our customers aren't looking for anything else.
"There are some nice seed-raised petunias but because of the branding and novelty value of cuttings-raised ones, they still hold sway. The true Wave series is seed-raised and a great performer.
"The market has expanded tremendously but now it's slowed. The single-flowered market is fairly flat. There are increases in sales in the doubles, though - the quality is unique. We keep adding new colours - there's still not a good yellow, and there's interest in the bicolours.
"We've got to be careful not to snow ourselves under with new varieties - we have to ask ourselves: 'How many petunias can the world stand?' At the end of the day, we've got to be honest and ask if they'll they do well in a garden situation."
"They are pretty foolproof. In high humidity powdery mildew and botrytis become a problem, but they don't suffer many pests or diseases. After the virus disaster in the 90s we learned a lot and I haven't seen any problems for at least 10 years."
Caroline Dumville, partner, Primrose Cottage Nurseries, Manchester
"We're finding petunias have declined in popularity this year. If you don't get a good summer, the rain marks the flowers.
"We mainly grow the Frenzy varieties because they've got such a good colour range and perform so well. 'Frenzy Velvet' is a deep burgundy colour and 'Frenzy Light Blue' is a lovely lavender that's very popular.
"There are lots of trailing varieties and they've taken sales away from the bedding petunias. We have trailing petunias in baskets and they just sell and sell when they're in flower."
- P. x hybrida 'Cascade Soft Pink' has bright, double flowers that are 10cm across and offer long-lasting colour.
- P. x hybrida 'Easy Wave Blue' is a trailing plant, growing to a height of 30cm and spread of 90cm.
- P. x hybrida grandiflora 'Superbissima' is a large-flowered Victorian variety with a variable habit, sometimes producing double flowers and sometimes singles with a dark eye. All come in shades of purple, mauve and pink, and have very frilly petals and exceptionally large blooms - though weather resistance is an issue.
- P. x hybrida 'Pearly Wave', like most of the seed-raised Wave series, has a sprawling habit and makes a sturdy plant with good staying power in the garden. It withstands bad weather well and produces pale pink flowers over a long period.
- P. x hybrida 'Prism Sunshine' is an award-winning grandiflora variety that remains very popular as a good yellow. Flowers are cream-edged with yellow throats.
- P. x hybrida 'Purple Wave' might be later to flower than many, but makes up for it with an abundance of blooms right through until the first frosts. One of the true Wave series, it is an excellent performer in a garden situation, with a trailing habit that makes it good for ground cover as well as baskets.
- P. x hybrida 'Ramblin' Scarlet' is one of a range of seed-raised, small-flowered petunias that make well-branched plants with a scrambling habit and are early to flower.
- P. x hybrida 'Surfinia Lime' is a subtly shaded petunia with large, trumpet-shaped flowers in creamy white with a green mouth. The plants are well-branched and robust, and have a trailing habit.
- P. x hybrida 'Surfinia Pink Ice' has pink flowers that are veined in purple, with variegated foliage and a compact habit.
- P. x hybrida 'Surfinia Sky Blue' Award of Garden Merit is one of the few Petunia varieties to get close to a true blue: the flowers start dark violet and fade to pale blue-mauve with age. It forms a large, bushy plant almost entirely covered in blooms when in flower. It also stands up to bad weather well and is lightly scented.
- P. x hybrida 'Tumbelina Candyfloss' has vivid pink, frilly-petalled, large, double flowers and - like all the Tumbelina series - performs well in hanging baskets.
- P. x hybrida 'Tumbelina Priscilla' was the first in the Tumbelina series and is still justifiably popular. It has deeply ruffled, fragrant, double flowers in mauve, with purple veining.
- P. x hybrida 'Tumbelina Rosy Ripples' is a new introduction, launched last year, with multicoloured, double flowers in pink, red and white with ruffled edges to the petals.
- P. x hybrida 'Viva Forest Fire' has very unusual reddish-orange colouring, which glows when the sun strikes it. A new introduction, it is one of the few varieties to approach the orange colour spectrum.