Pretty Peas - native pea flowers
Chorizema cordatum and Prostanthera ovalifolia. Photo - Linda Ross
Australia's native peas are dazzling in the wild and offer splashes of colour, and some challenges, for the home gardener. Graham Ross goes pea pod casting.
Any trip into the Australian outback will inspire you to grow eye-catching wildflowers with pea-shaped, butterfly flowers. Who could fail to be impressed by square metres of flowering Sturt's Desert Peas, mounds of fiery orange Flame Peas and curtains of purple Hardenbergia dripping down from taller host trees?
All are distantly related to edible peas but it's their flowers that appeal, not their fruit pods. There's plenty of variety among the native peas: groundcovers, annuals, perennials, shrubs and trees. Their flowers have delicate perfumes, a range of rich colours and while not large, make up for their size in the numbers they produce each spring.
Many native pea flowers have a reputation for being short-lived, so gardeners have tended to avoid them in the past. However, as we learn more about their cultivation and as plant breeders turn their attention to creating new varieties, native peas are now being seen in more and more home gardens.
Native pea varieties
Perhaps the most commonly grown of the native peas is the purple-flowered climber Hardenbergia. The best planting of Hardenbergia I ever saw was in Perth. The plant was growing up the trunk of a towering local gum and spilling down 5m or more. The gardeners had added extra strands of wire to encourage branching across an area 6m wide. In this shady area, the cobalt blue pea-flowers glowed. What added to this vision splendid was the neighbouring plantings of another native pea, the local Hovea trisperma. It too was in full bloom with its mauve-blue flowers standing proud on upright branches. If you're like us and planting on the east coast, then the indigenous Hovea species, H. lanceolata, will work nicely with the Hardenbergia.
Hardenbergia. Photo - Linda Ross
Other common pea-bushes are the loosely grouped 'bacon and egg' plants. Many genera belong under this common name and all have the characteristic bi-coloured orange and yellow pea-shaped flowers. Some grow in barren, sandy soils and shallow rock pockets while others thrive in moist, almost swampy conditions. Sadly, many that were native to vast tracts of land have been almost eliminated to extinction by the colonial graziers – they were poisonous to stock. These days, home gardens house many of these beautiful wildflowers.
In the bush, the quaintly named Running Postman, Coral Pea and Black Coral Pea, which are all Kennedia species can be seen scrambling across the ground and devouring shrubs that get in their way. Come spring, they are covered with masses of red or black and yellow flowers. They are vigorous, hardy climbers and will last for years. Given there are few true black flowers Kennedia nigricans, is a novel but practical plant to grow. The Scarlet Runner Pea, K. rubicunda, is another groundcover that is easy to grow up a trellis fence and has bright red flowers in spring.
Black running postman, Kennedia nigricans. Photo alybaba/Shutterstock.com
Flame Peas, Chorizema spp, are impressive shrubs for their quick growth and stunning sprays of orange flowers when grown in sun or shade. Undoubtedly though, the queen of the pea flowers is the groundcover Sturt's Desert Pea, Swainsona formosa. With brilliant red, large pea-shaped flowers and a glossy, black boss in the centre, it's a worthy selection for South Australia's state floral emblem.
As for the tallest member of the pea family, it's the Black Bean, Castanospermum australe, with its huge yellow and red flowers appearing on the older branches of the tree. The large seed pods were always used as boats by the 'gunmnut babies' in the books created by Australian children's book author and illustrator May Gibbs.
You can grow native pea plants
Growing native peas will take you into the challenging world of Australian flora where the plants are more soil and climate specific than most found at your local garden centre. That said, there's still a huge range to choose from that are suitable for your garden. Native plants are some of the most beautiful and complex in the world but they are not mainstream. I advise you to visit native gardens in Australia's Open Garden Scheme and specialist native plant nurseries – and that's half the fun. Of course, your local garden centre will be able to offer lots of advice. In the meantime, here are some guidelines to get your native peas under way…
In the garden
The best way to grow ornamental flowering peas is to create a bush garden. If you place these native plants, with their specific cultivation needs, into a regular garden bed with roses and other exotics, one group will die out. A totally native garden is the way to go. Start by removing large areas of grass and installing a good sub-surface drainage system. Next, cover the area with a free-draining sandy loam. Then mound the soil in a natural, irregular way to create a series of gullies and ridges. Large pieces of stone will help with this.
Hardenbergia in our bush garden. Photo - Linda Ross
Select 5cm small tube plants instead of 15cm or 20cm pots as they establish more quickly than larger ones. Place in as natural an arrangement as possible, taking into account their ultimate size. This avoids overcrowding and permits each plant to display its attributes. Water in the entire area then apply a mulch. Regarding mulch, I've seen a 5cm layer of pea gravel used effectively, yet most people go for a natural bush-chip mulch. If you opt for it, always determine what trees have been chipped for your mulch - eucalyptus and other native trees are okay, but camphor laurel can give you problems later as the essential oils drain out of the mulch and stunt or poison native plants.
Avoid strong fertilisers – instead, mix a handful of pelletted manure with a bucket of natural, leaf litter and sprinkle around the soil. This is enough to feed most natives. Those with extra flowers will benefit from a light sprinkle of a low-phosphorous granular fertiliser. Seaweed solutions are a great plant tonic too.
Care and propagation
Native peas will benefit from a light annual trim removing only 10-15cm after each flush of flowers (which might occur 2-3 times during spring and summer). This will keep the plants compact, and encourage them to produce more new growth and flowers. It also strengthens the plant against disease and insect attack.
Many peas are difficult to strike from cuttings or germinate from seed. Each plant will be different. Some seeds will need soaking in warm water for 24 hours while other species will strike from cuttings at different times of the year. You'll find reference books like Australian Native Plants (5th edition), by John Wrigley & Murray Fagg (Reed New Holland, $100), most helpful, and I can personally guarantee you'll find the whole native pea thing a lot of fun!
Our Favourite Pretty Peas
1. False sarsparilla or Happy Wanderer
Plant name: Hardenbergia violacea 'Happy Wanderer'
Description: variable habit from trailing groundcover to climbing plant, narrow grey-green leaves with masses of pea-shaped purple flowers in late winter and spring.
Size: 3-4m on the ground, or along a fence; 2m up a trellis
Symbols: Full sun and semi-shade, not frost tolerant.
Special comments: There are several cultivars with Plant Breeders Rights (PBR) including, Hardenbergia violacea 'Bushy Blue' with purple flowers, 75cm tall; Hardenbergia violacea 'Mini-Haha', dwarf, erect compact habit to 15cm with deep mauve flowers; Hardenbergia violacea 'Mini Magic', low, spreading to 1m wide and 15cm tall, excellent for rockery.
Hardenbergia violacea. Photo - Linda Ross
2. Sturt's Desert Pea
Plant name: Swainsona formosa (now renamed Willdampia formosa after its 1699 discoverer William Dampier)
Description: annual with deep red pea-shaped flowers with a glossy black central boss, appearing after rain on trailing 1-2m stems covered with hairy grey leaves.
Symbols: Full sun, frost sensitive.
Special comments: Can also be grown successfully in rockeries, hanging baskets and towers of terracotta pipes filled with gravel. Must have well-drained soil and don't like disturbance once growth has commenced. Snails love the foliage. Grown from seed sown in March or April, or from grafted plants.
Sturt Pea. Photo - Linda Ross
3. Flame Pea
Plant name: Chorizema cordatum
Description: Lime green heart-shaped leaves and masses of bright orange-red flowers in early spring to early summer.
Size: Compact shrub, 1x1m.
Symbols: Full sun to light shade, frost tender.
Special comments: Prefers a sheltered spot with good mulch.
Flame pea. Photo - Shutterstock.com
4. Dusky Coral Pea
Plant name: Kennedia rubicunda
Description: Dark green leaves and dull red pea flowers in spring.
Size: Vigorous to 3m as groundcover, 4-5m when grown along fence.
Symbols: Full sun and part shade, frost sensitive.
Special comments: All Kennedias are quick growing: K. nigricans has black and yellow flowers; K. retrorsa is rare but frost hardy.
Coral Pea. Photo - Linda Ross
Where to buy
* Specialist native plant nurseries.
* Forestry Commission Nurseries.
* Australian Plants Society http://farrer.riv.csu.edu.au/ASGAP