How to sow sweet peas for bunches of scented flowers in summer

By | January 10, 2018

Sweet peas can transform your garden into a scented and wonderfully coloured haven. Sowing and growing them can be as complicated or as simple as you like, and it’s a subject where experts differ. No worries! Just follow our straightforward approach.

Sow seed from now to March and you’ll have sturdy plants that will flower beautifully in the summer. Growing from seed also means you’ll have a better choice of colour and scent. Sweet peas usually flower from May to September but last year (2017) many were flowering well into the autumn. They are a great plant to grow in amongst the runner beans to encourage pollination.

Sweet peas by Bernard Spragg NZ. Notebook. bank holiday. summer scent

Sweet peas by Bernard Spragg NZ. Public domain.

Sowing sweet peas in the spring is OK

Although some people say that autumn is the optimum time for sowing sweet peas, it’s perfectly fine to sow them in the spring, as late as March.

Soak, nick or leave seeds alone?

Sweet pea seeds have a hard covering but many trials show there’s no need to soak them or nick the outside. They will germinate without any help.

Deep container or 9cm/3in pot?

Some people choose a deep container so the sweet peas can develop their nice long roots to anchor the plant in the ground. There are commercial products available for this (notably ‘Rootrainers’) but you can also use the tubes inside loo rolls.

You can also just sow three seeds in a simple 9cm/3in pot. When they germinate and grow you can plant out the entire potful and their roots won’t be damaged.

Sow in potting compost

Multipurpose compost will do. Some people lighten and aerate the mixture with some sharp sand and grit. Others add a bit of John Innes. Monty Don recommends a little sieved soil or garden compost.

Fill your 9cm/3in pot with potting compost. Space three seeds on the surface, press in gently and cover with a little more compost. Water in just a little. (Some people don’t water in at all.)

Keep them cool

To encourage germination, some advise covering the pots with newspaper or a polystyrene tile to keep light out and moisture and warmth in.

Keep them somewhere cool such as a cold greenhouse or cold frame. Last year I didn’t have either of these and was successful in germinating sweet peas on a cold bedroom window sill.

Many advise using mouse traps to keep mice from eating the seeds (which they love) as they germinate. Luckily, I didn’t have that problem in the cold bedroom.

Grow on

Seeds usually germinate in about a week. Remove the newspaper, if you’ve used it, when you see the first sign of germination.

After they’ve germinated, keep the seedlings cool with plenty of light in a cold greenhouse, cold frame or a bright potting shed. This will encourage root growth and sturdy plants. Keep the compost moist.

Pinch out the growing point

When the plant has three sets of leaves showing, remove the top (the growing point( above the second pair of leaves. Side shoots will then grow vigorously and a sturdy plant will develop.

Plant out and tie in

Plant out the seedlings as soon as conditions are favourable, from about February. Fill the bottom of the hole with well rotted garden compost and mulch with compost to retain moisture in the soil. Tie the young plants into a framework (a wigwam, perhaps, or an arch) to encourage them to grow upright and produce straight flower stems and better flowers.

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/

Look forward to picking bunches and bunches of lovely scented flowers, all through the summer. Keep picking and the plants will keep flowering.