Many people will associate this genus with the invasive Himalayan balsam, I. glandulifera, an annual that has caused serious problems with our waterways. Fortunately, there are many more species that do not cause such problems.
Originating from the sub-tropics and tropics of Asia and Africa, there are around 850 species of Impatiens within the Balsaminaceae family. The genus consists of succulent stemmed annuals, evergreen perennials and sub-shrubs. Leaves are lush, occasionally semi-translucent and vary from being alternate, opposite and whorled. The flowers are its main attraction and are usually bright in colour, five-petalled, spurred and sometimes hooded. They can be borne singly, clustered or in racemes and scented, depending on the species.
There are basically two types of Impatiens, the bedding type and the non-bedding type. Bedding types are cultivars derived from species such as I. walleriana (busy Lizzies) and I. schlechteri, also known as I. hawkeri (New Guinea hybrids). These are fast-growing plants that can provide both pastel and vivid colours, suitable for many planting schemes.
Busy Lizzies and New Guineas are sub-shrubby perennials that are traditionally grown as fast-cropping annuals for bedding and container displays. There are hundreds of cultivars produced from these, with series of F1 hybrids providing large, showy, long-lasting flowers.
The species are less forceful on the eye than the traditional bedding hybrids but this makes them no less worthy of attention. Used similarly, forms such as I. niamniamensis 'Congo Cockatoo' and I. arguta will add a subtlety to displays and borders. I. tinctoria and I. scabrida can be used in herbaceous borders, while the 15cm-high I. omeiana has a spreading habit and is ideal as ground cover in shady areas.
A balanced feed should be introduced during planting with additional feeds occurring regularly throughout the season. Plant in a sheltered site in a humus-rich soil with good drainage. Most types are shade-tolerant but many, except the newer hybrids, will not withstand direct sunlight for prolonged periods.
Both annual and perennial species can be propagated from seed in spring and soft stem tip cuttings can be taken from perennials in spring or summer. Both are susceptible to damping off and scorching from direct sunlight. Botrytis can be troublesome to flowers if conditions are too damp. Red spider mite, aphids, whitefly and vine weevil all pose threats to glasshouse plants.
WHAT THE SPECIALISTS SAY
- David Spray, partner, Pentland Plants, Midlothian
"Busy Lizzies are probably our main line. They're good, colourful flowers and much cheaper than geraniums.
"Our most popular variety is Xtreme from Goldsmith. It's popular for parks and a mainstay of amenity planting. There are a lot of F1 hybrids and there are no bad ones.
"SunPatiens is expensive and doesn't do so well in the cool conditions we have in Scotland. New Guineas, though, are getting more popular - but more at retail.
"In the south of England there is a problem with downy mildew among cutting-raised plants. It can spread to seed-raised ones, and of course it's difficult to treat once they are planted out. We've never had it in Scotland, though - possibly because we don't import them."
- Alex Newey, managing director, Young Plants, Warwickshire
"We do three series, each with different habits. Xtreme is a compact pack product that's very grower-friendly. Accent is a little larger. But the one we have been promoting is Envoy from Bodger Seeds, which is a spreading, trailing form in eight colours that puts on a big show."
- Derry Watkins, proprietor, Special Plants, Wiltshire
"We specialise in tender perennials, which includes an interesting range of Impatiens species. One-third of these are hardy in the UK, like I. omeiana, I. arguta and I. tinctoria. The remaining ones we sell are tender species that provide colour, form and scent throughout the year under cover.
"They can also be used in borders and bedding schemes where a more subtle, shade-tolerant but ultimately interesting plant is required.
"Personal favourites include I. namchabarwensis, a rare blue-flowered species. Hybrids of I. kilimanjari are attention-grabbers, with thousands of tiny flowers creating a carpet of colour. I. tinctoria is borderline hardy, with purple-throated flowers. We also sell the new hardy annual I. scabrida, which has pale yellow flowers on dark foliage.
"We sell Impatiens in 7cm to 2-litre pots and they are popular with people who want something a little different and special in their displays. Being easy to propagate, they are excellent value."
- Brandon Cooke, Rowan Landscapes, Oxfordshire
"We mainly work on private contracts, carrying out maintenance and sward management. Many clients have bedding displays that we are responsible for designing, planting and maintaining.
"Impatiens plants are good to use in our circumstances where time is a major factor. They are reliable and require little maintenance, except for feeding every so often, and provide exceptional colour for a long season. We're using I. Xtreme 'Red' and Mosaic 'Orange' alongside Phormium 'Sundowner' for a really hot summer border this year."
SPECIES AND CULTIVARS
- I. arguta is a hardy species that has dark red, arching stems and big violet flowers. It grows to a height and spread of 45cm.
- I. balfourii has purple, pink and white hooded flowers with an overall height of 60cm. It self-seeds readily and is tolerant of shade.
- I. balsamina Tom Thumb series is dwarf, sparsely branched, slightly hairy annual with toothed leaves. The plants have double pink, scarlet, violet or white flowers. It grows to 30cm with a spread of 45cm.
- I. hawkeri Harmony series features vigorous yet compact plants with uniform growth. Varieties include 'Orange Blaze', 'Dark Red', 'Salmon', 'Pink Smile' and 'Violet'. Height and spread are 35-50cm.
- I. hawkeri Musica series features branched, compact shrubs ideal for bedding, containers and baskets. They are shade tolerant with colours ranging from 'White Blush' to 'Ruby Red' and 'Pink Blush'.
- I. kilimanjari subsp. kilimanjari is a tender plant useful for large areas of colour, with tiny pink and yellow flowers. It grows to 10cm with a spread of 75cm.
- I. kilimanjari x pseudoviola has small, red flowers which bloom en masse under glass. It grows to 10cm with a 75cm spread.
- I. namchabarwensis is a rare, blue-flowered species from Tibet, which is being tested for hardiness. Its height and spread are 35cm.
- I. niamniamensis 'Congo Cockatoo' is a short-lived perennial with narrow, hooded yellow and red flowers with distinctive spurs. It grows to 90cm with a 35cm spread.
- I. omeiana is a ground cover species growing to 15cm high. It prefers shade and has large, yellow flowers over dark foliage.
- I. scabrida is a rare hardy annual or tender perennial that reaches a height of 45cm and has large, pale yellow, white-lipped flowers.
- I. SunPatiens is a range of hybrids billed as the first sun- and heat-tolerant Impatiens when it was launched two years ago. It has since been expanded to include "compact" and "vigorous" series.
- I. walleriana Accent series features compact cultivars with flower colours including white and shades of orange, pink, crimson, red, lilac, violet and lavender-blue, some with central stars. Its height and spread are 20cm.
- I. walleriana Confection series has double or semi-double flowers in shades of red or pink.
- I. walleriana Mosaic series offers unusual marble-effect petals in three colours. It is effective in planters and windowboxes.
- I. walleriana Super Elfin series has oval leaves and small, flat, spurred, flowers. Its height and spread reaches 20cm.
- I. walleriana Swirl series has light green to red flushed stems and leaves. In summer the plants bear flattened, slender-spurred, pastel-coloured flowers with darker margins. It grows to 15-20cm high with a 60cm spread. It can be grown at a minimum temperature of 10 degsC.
- I. walleriana Xtreme series is fast-growing and uniform in shape. The series features a number of plants with Awards of Garden Merit including 'Salmon' and 'White', with a range of other colours from 'Deep Salmon' to 'Orange'.