Sweet pea (Lathyrus odoratus) and Baby's breath (Gypsophila elegans). Sweet peas

Sweet pea (Lathyrus odoratus) and Baby's breath (Gypsophila elegans). © Juni da Kyoto and reused under https://creativecommons.org/licenses/by/2.0/

Fact file: sweet peas

Latin name: Lathyrus odoratus

Type: hardy annual, climber

Origin: Sicily – first grown in Britain in 1697

I have a soft spot for sweet peas and they are easy to grow. Follow these straightforward steps to grow beautiful plants and fill the house and garden with colour and scent.

When to sow

You get the best flowers for longer if you sow sweet peas in pots with a bit of protection now, in March.

What to sow

Sweet peas come in a range of lovely pastel colours. Most are scented but, just to be sure, make sure that scent is mentioned in the description when you choose your seeds. Try a semi-grandiflora variety for scent, size of flowers and length of stem.

How to sow

Other people swear by soaking or nicking sweet pea seeds, and by using root trainers or tubes from loo rolls. Like Monty Don, we will keep sowing sweet peas simple.

  1. Sow three seeds to a 8cm/3in pot in normal peat-free potting compost.
  2. Fill the pot three-quarters full of compost and tap it on the bench a few times to settle it.
  3. Place the seeds on the surface of the compost and cover with a handful more, say 1cm/½in, of potting compost.
  4. Put the pots in a tray and place it somewhere cool with a little bit of protection – a cold frame, the greenhouse, on a cool window ledge, in the porch, or in the conservatory if it’s not too warm.
  5. The seeds will germinate quite fast at this time of year. Keeping them cool (they tolerate down to -5C) will ensure that roots develop well and the shoots stay firm.

Caring for your seedlings

You want your sweet pea plants to be strong and bushy, not weak and willowy. To achieve this, pinch out the tip of the seedling (using your thumb and finger) when it’s about 10cm/4in high. This will encourage strong side branches. (As ever in gardening, not everyone agrees that this is necessary …)

Harden off the young plants by putting them outside for increasing periods of time before planting them out in late April or May, depending where you are in the country.

Plant them out

Sweet peas are happy to grow in a container or in the open ground but they do best in fertile, well-drained, humus-rich soil. Add some garden compost to the planting spot. They like a nice sunny place but can perform even better and longer in very light dappled shade.

Plant out the groups of seedlings just as they are, about 20-25cm/8-10in apart. After planting, water them well and don’t let them dry out during dry spells. They will probably need some protection from slugs and snails as young seedlings are easy and tasty to eat.

Give your sweet peas some support

Sweet peas climb using tendrils which curl around any support they can find. Once they’ve found support they just keep on going! You can grow them up branches, netting, pea sticks or trellis. Bamboo canes are a bit too smooth. You could go for a wigwam of woven hazel or a sturdier obelisk. Whatever you provide, make it about 15 cm/6in shorter than you think the sweet peas will grow so that the frame is covered by flowering time.

Lathyrus odoratus - sweet pea tendrils. Sweet peas

Lathyrus odoratus - sweet pea tendrils. © Frank Vincentz and reused under https://creativecommons.org/licenses/by-sa/3.0/

When will they be in bloom?

Sow in March and you can expect beautiful flowers by late spring or early summer.

Keeping them going

Remember to keep picking the flowers as this stops them from setting seed and keep the plants flowering.

Sweet peas are hungry so if your soil is poor, feed them with a weak liquid tomato feed every fortnight.

Can’t sow or forgot to sow seed?

Buy some sweet pea seedlings from the garden centre. There will be less choice of colour and scent but they’ll still be glorious!

Sweet peas by Bernard Spragg NZ.

Sweet peas by Bernard Spragg NZ. Public domain.

Take a picture

If you're successful with sweet peas do take a photograph and enter it in our Rattan in the Bloom competition!