Home Propagation Sweet peas

Sweet peas

Sowing in spring, autumn or late winter

I can go a little overboard with my enthusiasm for sweet peas – in 2015, I ended up with nine packets, most of which I gave away.

It’s fair to say, 2016 wasn’t a vintage year for sweet peas. Best performer by far was old standby Cupani (www.mr-fothergills.co.uk). You can’t beat the fragrance and although the flowers aren’t as big as some of the modern hybrids, they’re an intense burgundy red/purple bicolour.

New variety Harrogate Gem from Matthewman’s (www.sweetpeasonline.co.uk), new for 2016, bred to commemorate the 40th anniversary of the Harrogate Autumn Flower Show performed reasonably well. It’s a long-stemmed red variety with very large, scented frilly blooms.

Singing the Blues, (www.mr-fothergills.co.uk) was a free packet, a mixture ranging from rich deep blues to pastel shades. Mixed with Cupani, it did very well.

Lastly, there was Eleanore Udall, a new form with graduated pink petals and good scent. It’s available from Thompson & Morgan and is raising funds for Thrive, the leading charity in the field of disability and gardening. For more information visit www.thrive.org.uk. Eleanore Udall has been named after the wife of Thrive’s founder, Geoffrey Udall. Fifty per cent of the money generated from each sale will go to Thrive.

Sadly, it didn’t flower well at all, I’m hoping because of a very slow start to the summer – it didn’t ever catch up.


potted-guide-logoPotted guide: sweet peas

Sweet pea Harrogate Gem
Sweet pea Harrogate Gem, early March
  • SOWING TIME: January-March or September-October under glass; April-May directly outdoors.
  • FLOWERING TIME: May-October. Pick blooms regularly to prolong the flowering season.
  • PLANTING DISTANCE: 30cm (9″-1ft) apart.
  • ASPECT AND SOIL: Full sun, well-drained – support needed for tall varieties.
  • HARDINESS: Protect against frost.
  • DIFFICULTY: Quite easy – but wait until March if you are sowing indoors without a propagator or light source. Protect seedlings against bird damage with short twigs.

Late winter and spring sowing

Sweet pea Hi-Scent
Sweet pea Hi-Scent – terrific perfume

There are rituals surrounding sweet pea seeds: soaking them overnight to soften the seedcase; filing a spot on the coat.

I don’t do either of these and have always had a good germination rate, as long as the soil is moist and the temperature constant.

Sow indoors, January-March, 1.5cm (½”) deep, either five seeds per 12cm (5″) pot of compost or 3-4 seeds in a family-sized yoghurt pot.

Water well and place in a greenhouse, cool windowsill or thermostatically-controlled propagator at a temperature of 15°C (60°F). Keep the pots moist, germination occurs in 12-21 days.

Once through, make sure the seedlings have good light, to avoid weak, leggy growth. Pinch out the growing tip, when two pairs of leaves have formed, to encourage bushy growth.

Gradually harden plants off before planting out into well-drained soil, April-May, 30cm (12″) apart and support with tall canes or netting. Protect from frost.

You can sow directly outdoors in April-May, where they are to flower, 1.5cm (½”) deep. Station sow two seeds together, every 30cm (12″), then remove the weaker. Easier, but flowers are much later.


Autumn sowing

Some people swear by sowing sweet peas in pots in September/October, for earlier flowering, but they need to be overwintered in frost-free conditions.

Sweet pea Old Spice
Old Spice, still flowering on November 1

 Sow 1.5cm (½”) deep, either five seeds per 12cm (5″) pot of compost, or I find 3-4 seeds in a family-sized yoghurt pot works well, as they like a deep root run.

 Water well and place in a greenhouse, windowsill or thermostatically-controlled propagator at a temperature of 15°C (60°F). Keep the pots moist, germination occurs in 12-21 days.

 Once through, grow on in cooler conditions, making sure the seedlings have good light, to avoid weak, leggy growth, especially important when overwintering. Pinch out the growing tip, when two pairs of leaves have formed, to encourage bushy growth.

 To overwinter seedlings, you’re aiming for plants with maximum root growth, not top growth. Keep them in a frost-free place, such as an unheated greenhouse, porch or cold frame. They will survive temperatures as low as -5°C, but not prolonged freezing. Even if all top foliage dies off, if there’s a strong root system, there’s a chance they will recover.

The last thing they need is keeping them too warm, as that will lead to weak growth, susceptible to colder weather and pests. Give them plenty of ventilation – you should only have 4-6″ of growth by spring.

Protect from slugs, snails, and mice. Gradually harden plants off before planting out into well-drained soil, from mid-March (if your soil is drying out and warming up – if in doubt, wait), 30cm (12″) apart and support with tall canes or netting.

Protect from late frosts with fleece.


Cottage garden plant’s exotic heritage

Heritage sweet pea Cupani

Although seen as an English cottage garden plant, sweet peas most probably came from Sicily, or Malta.

Francisco Cupani recorded it as being a new plant on Sicily in 1695. He was charged with the care of the botanical garden in Misilmeri, near Palermo.

British botanist Dr Robert Uvedale introduced the sweet pea in his garden, with an herbarium specimen from 1700 surviving, now in the Natural History Museum.

Sweet pea Robert Uvedale
Sweet pea Robert Uvedale

Both men have varieties named after them – Cupani is a Grandiflora heritage variety, similar to the old plant, with very strongly-scented small bicolour flowers.

Robert Uvedale made its debut in 2014, bright pink with large frilly blooms.

Silas Cole, a gardener working for the Spencer family (of Diana, Princess of Wales fame), bred a plant with bigger flowers and a wavy petal edge in 1900. It was bright pink and named Countess Spencer, the first of many ‘Spencer’ introductions.