How to grow Sweet Peas

Named for their fragrance and pretty pastel colours, Sweet Peas found their way into our gardens (and our hearts) over 300 years ago. Today, there’s a vast range of flower colours available, including deep velvety shades of blue and maroon, crimson-and-white streaked, and ruffled floral forms. They are an excellent cut flower, easy to grow, and many varieties will self-seed.

I have never grown Sweet Peas. Happily, this is about to change. I do not intend to spend the rest of my life thinking, if only I’d gotten around to growing Sweet Peas! My son is coming to visit and we’re going to create some brand new beds in my sunny front garden.

I’ll be planting climbing Sweet Peas. Dwarf varieties are available, but I prefer the traditional. I have fond memories of grandfather’s trellises, which seemed to tower overhead, and the fragrant posies he picked for me to take home.


The simple beauty of Sweet Peas

I haven’t yet decided whether to use a trellis, a tepee, or biodegradable netting strung between poles, to support the plants. The structure must be sturdy enough to last through 6 months of growth during autumn and winter, and the spring flowering. Whatever support I use will be set up before sowing, to avoid damaging the young seedlings as they establish.

Short day length (“winter-flowering”) types, that initiate flower in 10 hours of daylight (the Australian Early varieties are this type- more about these, below), should be planted in autumn. These will actually flower in the short-day months of early spring, and hopefully there will be two flowerings. There are also “spring/summer flowering” types, that initiate flower in 11-12 hours of daylight. I don’t know if this latter type is suitable for our summer climate here in the Central West.

Sweet Peas will grow in any soil, but (unsurprisingly!) perform best in a rich and friable loam. I’ll add organic matter to my rather clayey soil to help ensure the roots have access to soil moisture in the warmer weather. After adding the organic matter I’ll test the soil pH (for information about soil pH test kits, see my post My Big Gardening Weekend) and if the pH is under 7 I will add some hydrated lime before sowing.

Tradition dictates that Sweet Peas should be planted on St Patrick’s Day, 17th March. I will plant my seeds direct on that date, and will take precautions to protect the seedlings from snails and slugs. They can be raised in seedling trays and planted out. I may do this as well, if the extreme heat persists through March.

If successful I’ll be doing everything I can to ensure extended flowering. It’s very important to pick the flowers as they open. Flowers not picked will mature into seed pods and the plant will stop producing more flowers. Regular watering will also help to extend the flowering.


Self-seeded, fragrant and glorious in Mudgee

Sweet Peas were some of the earliest flowers to be selectively bred for domestic gardens. In 1699 a Sicilian Monk, Father Francisco Cupani, sent a few seeds of the wild Lathyrus odoratus to his friend Dr Uvedale in the UK. The flowers all had a purple standard and a sky blue wing petal, but the seeds contained the genes for all the colours, and forms, and the fragrance, that we now enjoy.

Around 1720, some flowers were sent to the London Flower Market where they received their enduring nickname, ‘Sweet Pea’.

The pink and white flowered Painted Lady was the first named cultivar offered in 1731. For the next 100 years, only a handful of colours were available. That changed when, towards the end of the nineteenth century, English and American growers began sharing their seeds and knowledge, giving rise to an explosion of varieties on both sides of the Atlantic.


A lovely posy, with rosemary for remembrance, in my grandmother’s vase

In England, in 1901, the Earl of Spencer’s Head Gardener, Silas Cole, presented, at the National Sweet Pea Society’s first ever show, a variety he named after Princess Diana’s grandmother, Countess Spencer. It was unique in having a waved standard petal.

By 1918, in America, the Philadelphia based seedsmen, W. Atlee Burpee & Co were offering over 170 Sweet Pea varieties.

Most of the Sweet Peas offered in Australia in the first half of the twentieth century were Australian Early Flowering Sweet Peas. Apparently, the tradition of sowing Sweet Peas on St Patricks Day was a specific requirement of Yates’ early flowering “Yarrawa” variety, and is not necessarily applicable to varieties originating from other stock. As far as I’m concerned, that technicality can be overlooked!

Have you tried the long day-length varieties? Let me know!

Do you have childhood memories of Sweet Peas? I’d like to hear about them.


5 Comments Add yours

  1. janesmudgeegarden says:

    I grew sweet peas for the first time last year. They rapidly became unruly,and the stems very short, I suspect because I didn’t pick enough of the flowers. I didn’t know there are different kinds, so your blog, full of interesting information, is most timely.

  2. tonytomeo says:

    The season here is SO brief for them. My niece still grows them annually. She really digs the fragrance.

  3. margaret says:

    I would love to grow sweet peas this year. When I have tried previously, mildew has been a big problem.

    1. My Dream Garden says:

      That’s a shame. Our dry climate means mildew is not so much of a problem, although it does affect pumpkins and zucchini in the summer. This year I finally had success by training cucumbers up a trellis, which I think got them out of the more humid zone close to the ground. They’re still going!

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