Catriona McLeodSweet peas: elegant ladies (& a few gents)

One of the prettiest, sweetest-smelling and most prolific flowers of spring is the sweet pea, Lathyrus odoratus. Any Victorian or Regency garden of note had multiple trellises of this frost-hardy, twining, annual climber.

Lathyrus.odoratus. 'High.Scent'

Lathyrus odoratus ‘High Scent’

Victorian gardeners, particularly, planted for scent, high colour and exoticism. Their gardens featured swathes of Narcissus, stands of hollyhock and Delphinium, plots of bobbing Anemone hupehensis, snapdragons, asters, dahlias, collections of Galanthus and tiny alpines, hyacinths, petunias, tulips, Irises, kniphofias, salvias, lilies, paeonies, Oriental poppies, verbenas, vast beds of pansies and other bedding annuals, and of course, long-stemmed, multi-coloured sweet peas.

Sweet peas had been cultivated since the 1600s in their native Sicily. These original plants had weak stems and small flowers, but an intense ‘orange-jasmine-honey’ perfume. Some 6,500 sweet peas are now available, and these have been bred from just two plants. The first, Lathyrus odoratus, is an annual species with deep-blue and purple flowers and the same delicious perfume, which hails from coastal regions of the Mediterranean.

Lathyrus odoratus 'Painted Lady'

Lathyrus odoratus ‘Painted Lady’

The other probable parent is a pink and white pea known at the time as Lathyrus zeylanicus (now Lathyrus odoratus ‘Painted Lady’), first recorded in England in 1737 by Philip Miller, the then curator of the Chelsea Physic Garden. Early crossing, selecting and and re-crossing produced a pure white variety, followed by splashes (or ‘breaks’) of red, black and scarlet. During the late 19th century new commercially available varieties began to appear frequently and were sought by passionate gardeners and breeders, near and far.

Scot Henry Eckford (1823 – 1905) was the most famous breeder of sweet peas in the UK. Liberty Hyde Bailey, the American horticulturalist, botanist and cofounder of the American Society for Horticultural Science, described him as ‘the prince of specialists’. Eckford perfected the breeding of his Grandiflora Sweet Peas, which were a great improvement over previous varieties, and many became highly popular in America, and the UK.

Sweet Peas are now divided into three main groups.

Lathyrus odoratus (Cupani) Photo Magnus Manske

Lathyrus odoratus ‘Matucana’ or ‘Cupani’ Photo Magnus Manske

1. Old-fashioned varieties, bred from the Sicilian species Lathyrus odoratus, which includes ‘Matucana’ – also called ‘Cupani’ or ‘Cupani’s Original’. Sicilian monk Francesco Cupani first sent these seeds to England and Holland in 1699 and its seed was being sold commercially by 1724. ‘Matucana’ has a deliciously strong scent, although its purple and deep red, bi-colour flowers are quite small in comparison with more modern varieties. As this is a less vigorous variety it is suited to a large pot – supported by canes – making it a good balcony specimen.

2. Spencer cultivars – these are modern sweet peas, developed by the late Princess of Wales’ family. Silas Cole, the Head Gardener at Althorp Park (the Spencer family estate), discovered a particularly large, frilly, multi-flowered variety, which he named ‘Countess Spencer’, and a legion of Spencer varieties was born. There are now hundreds of Spencer Sweet Peas ranging from white, through to pink, violet, deep purple or bright red and they produce large flowers – four to five on a stem – on long, straight stalks.

Lathyrus odoratus 'Almost Black'

Lathyrus odoratus ‘Almost Black’

3. Modern Grandiflora Sweet Pea – Lathyrus odoratus ‘Almost Black’ (incredibly dark, luscious colour with an incredible scent) is an example of a Modern Grandiflora Sweet Pea. These have been developed to have lots of large flowers on the long stems of the Spencer types, with the fantastic scent of ‘Matucana’.

This year I am trialing five old-fashioned varieties purchased from an heirloom seed company in the UK. ’Fire & Ice’ is a tall grower (to two metres) and has a standard marked with a crimson flare, while the wings start with a purple Picotee edge, which slowly suffuses the petals as the flower matures. ‘Fire & Ice’ is one of the most vigorous and highly scented of the Grandiflora Sweet Peas. (Note: Picotee is a variety of flower whose edge colour differs from the flower’s base colour. The word is from the French picoté -‘marked with points’).

‘King Edward VII’ (one of the gents of the title) is a highly scented, heirloom, Grandiflora type introduced by Henry Eckford in 1903. Deep crimson with three strongly scented flowers per stem, it is taller and stronger growing that most Grandifloras and was awarded the RHS Award of Garden Merit (AGM) in 1995.

Lathyrus odoratus 'Dorothy Eckford'

Lathyrus odoratus ‘Dorothy Eckford’

‘Dorothy Eckford’ is an outstanding pure white heirloom sweet pea introduced by Eckford in 1901 and awarded the RHS Award of Garden Merit (AGM) two years later. It was considered superior to the early pure white Spencer Sweet Peas and it remained an important commercial cut flower until about 1920, although it has regained recent favour due to its beautiful form and perfume. Dorothy and King Edward have been very slow to germinate for me this season and I may have to plant more, or re-plant the same seeds, after scarifying them by rubbing the testa (seed coat) with very fine sandpaper, and soaking them overnight in warm water.

Lathyrus odoratus 'Sweet Velvet'

Lathyrus odoratus ‘Sweet Velvet’

As noted, ‘Painted Lady’ was one of the first Sweet Peas to be bred and named by plant enthusiasts. It is a soft rose, pastel pink and cream bi-colour that is highly scented, early flowering and heat tolerant. I am also growing, from my own seed, ‘Sweet Velvet’. Originally collected from an old cottage garden in Hobart, this old-fashioned sweet pea has amazing deep maroon fragrant flowers and long stems; however, my greatest success has been with ‘High Scent’ (also known as ‘King’s High Scent’ or ‘April in Paris’).

Lathyrus.odoratus.'High.Scent' copy

Lathyrus odoratus ‘High Scent’

This is a super-fragrant, large-flowered, and delicately coloured Sweet Pea: the blooms are a creamy shade of white edged in lavender. ‘Sweet Velvet’ and ‘High Scent’ look and smell wonderful if placed in a vase together.

Sweet peas are really so easy to grow. The seeds are best if soaked for 24 hours before planting. I never sow mine directly because of the blackbirds and their need to dig over every seed and seedling in the garden at this time of the year. I keep the seedlings only lightly watered and warm (I put them out in the sun and bring them in at night). When they have developed a good set of leaves and are about 100mm tall I plant them out into a prepared bed, according to the pH of the soil (do a soil test first). Knowing they hate the wind means I select a sunny, calm area for a trellis or cane pyramids.

Sweet Pea seedlings in coastal sun

Sweet Pea seedlings in coastal sun

Lathyrus sativus Photo Llez

Lathyrus sativus Photo Llez

I am a devotee of sweet peas and I adore their pretty frilly faces and their uplifting perfume. A vase of long-stemmed sweet peas will brighten any dark corner or grey afternoon. But take care; unlike common peas, the seed of the sweet pea is highly poisonous. Although no records of toxicity have been found for this plant, the seed of some species in this genus contain a toxic amino acid that can cause a severe disease of the nervous system known as ‘lathyrism’ if they are eaten in large amounts. Lathyrism (or neurolathyrism) is a neurological disease of humans and domestic animals and the problem is most commonly associated with Lathyrus sativus (‘Grass pea’, ‘Kesari Dhal’ or ‘Khesari Dhal’). The lathyrism resulting from the ingestion of Lathyrus odoratus seeds (Sweet Peas) is often referred to as ‘odoratism’ or ‘osteolathyrism’ and is caused by a toxin that affects the linking of collagen in the cell tissue. Suffice to say, a stomach upset may result from acute ingestion.

Lathyrus latifolius 'White Perle'

Lathyrus latifolius ‘White Pearl’

As an afterword, Lathyrus latifolius is a perennial sweet pea, which can reach two or more metres by means of twining tendrils. It is frost-hardy, long-lived and slowly spreading. It is less strongly scented than Lathyrus odoratus, with which it is often confused, and the flowers are smaller and usually single-coloured. Numerous cultivars have been selected as garden subjects, including Lathyrus latifolius (pink), ‘Alba’ (white), Lathyrus latifolius ‘Rosa Perle’ (syn. ‘Pink Pearl’, pale pink), and Lathyrus latifolius ‘White Pearl’ (white). I have grown the latter two cultivars. They are really tough repeat performers and worthy of a sunny position where they can scramble and roam …

… but nothing makes a nicer gift than a bunch of annual sweet peas, picked with the dew still on them, for their sunny warmth and heady scent.

The odor of the sweet pea is so offensive to flies that it will drive them out of a sick-room, though not in the slightest degree disagreeable to the patient.
[A tip from The 1899 Old Farmer’s Almanac]

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Catriona McLeod

About Catriona McLeod

Dr. Catriona McLeod is a writer, environmental & cultural consultant, horticulturalist and designer based in Tasmania. Catriona worked as a horticulturalist in plant nurseries, while studying architecture and landscape architecture in Brisbane. After travelling, and working as a designer and horticultural consultant, she completed a PhD in green design. Until 2012 she taught design principles, landscape architecture, ecology, design theory, horticulture and sustainable practices at the University of Tasmania. She is a passionate advocate of wild places and the preservation of threatened environments and species and is, of course, an avid and always-learning gardener.

7 thoughts on “Sweet peas: elegant ladies (& a few gents)

  1. Sandra Pullman on said:

    Your sweet peas look gorgeous. I planted some but the rats or possums ate them. Before I plant any more need to work out how to protect them. Not happy Jan.

    • Catriona McLeod on said:

      HI Sandra,

      Sadly, I don’t know what to recommend, apart from encasing the plants in chicken wire. I have both possums and rabbits where I live but they seem to leave them alone. The blackbirds, snails and slugs are more of a concern.

      The Sustainable Gardening Australia website has some great ideas for keeping possums away from plants: http://www.sgaonline.org.au/living-with-possums/

      Cheers, Catriona

  2. Lynn on said:

    Hi Catriona – I love sweet peas too. Planted them on Anzac Day – just like you’re supposed too – and they’ve been razed to the ground by rabbits, possums or mice – not sure of which. So now I have to put chicken wire all around them which is definitely NOT attractive in the garden. Where can I buy the special cultivars (I just get my seeds from Bunnings – very boring!). I’d like to try and plant a few of the different species. Also, I get a lot of green growth but not a lot of flowers – do I need to add something to the soil?
    Thanks,
    Lynn
    Interesting about the toxicity…didn’t know that. Hasn’t killed the horses yet!

    • Catriona McLeod on said:

      Hi Lynn,

      I usually source my sweet peas from local heirloom growers here in Tasmania, but I will track others down on the internet. A lot of the commercially available seeds are F1 Hybrids, which can mean four things:

      1. They don’t always come true from seed in successive years, as they are the result of controlled (not open) cross pollination.
      2. F1 hybrids may be reliant on intensive cultivation based around chemicals.
      3. They are often more expensive.
      4. They are often less robust than heirloom varieties.

      That said, there are some very good sweet pea hybrids and cultivars available, particularly online. I think the proof is the reliability in successive years. I bought ‘High Scent’ from a well-known commercial supplier of seeds and it hasn’t let me down in three years. The supplier from whom I sought seed in the UK sent them very quickly and they passed through customs/quarantine efficiently. I also ask neighbouring gardeners for a few seeds if I spy a sweet pea performing well in their garden. Garden markets are also a good source of seed, information and swapping!

      In terms of all of the green growth – you are being way too kind and feeding them with too much nitrogen. Find a liquid fertiliser in which the N:P:K ratio favours Potassium; the general dictum being Nitrogen for green leafy growth, Phosphorus for healthy root and shoot growth, and Potassium for flowering, fruiting and general hardiness.

      It isn’t too late this season to have another go, but you may have summer flowers instead.

      Hope this helps,

      Catriona

      • Lynn on said:

        Thanks Catriona for the update. I will check commercial suppliers…

  3. Lovely post .. adore sweet peas… have never grown them, but always buy a bunch when I see them on sale.
    They got me into big trouble when I was seven years old and an aunt gave me a bunch for my mother on my way home from school. BUT – I was not supposed to be at this cousin’s house and feared what my mother would say when she discovered I’d gone there, disobeying her. So I threw the bunch away before I got home. I was outed anyway, cos the two subsequently talked and the topic of the sweet peas arose. I was so busted!
    Did not turn me off these lovely blooms, though. Just makes me chuckle recalling the drama of it all.

    • Catriona McLeod on said:

      Hi Julie,

      Thank you for your compliment and story. I too got into trouble regarding sweet peas – but in this case it was for pinching the ones that hung down low over a neighbour’s fence. They have been beguiling me for decades!

      Cheers

      Catriona

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