How to grow sweet peas

Sweet Pea 'Top to Bottom' from Thompson & Morgan

This cottage garden classic is colourful, fragrant and easy to grow
Image: Sweet Pea 'Top to Bottom' from Thompson & Morgan

Sweet Peas are one of the most popular cottage garden flowers, prized for their beautiful blooms and gorgeous scent. Trained onto a wigwam-shaped plant support they form an impressive column of fragrant, summer colour in beds and borders. Growing and planting Sweet Peas Is Easy and they are excellent cut flowers, the more you pick the more they’ll grow.

There are two types of sweet pea. Annuals last for one season and everlasting perennial varieties return year after year, but are much less fragrant. Read our handy guide on how & when to sow Sweet Peas from seed below.

How to sow sweet pea seeds

seedlings growing in a carboard tube

Some gardeners sow their seeds in toilet rolls to create a deep, narrow root run
Image: Ian Grainger/Shutterstock

Growing sweet peas from seed couldn't be easier. You can sow them into pots of compost in autumn and overwinter the young plants in a cold frame or cool greenhouse. Or, you can wait until spring when you can sow into pots or directly into the ground.

To prepare the seeds, leave them on moist kitchen roll until they swell or sprout. Lay the kitchen roll in a sealed container and place it in a warm room. This helps get them off to a quicker start but isn't essential as your seeds will still germinate well in moist soil. Use a good quality compost and sow several sweet pea seeds to a pot. Plant them about 1cm deep, cover with compost and water them well.

Sweet peas perform best if their roots are forced to grow in a deep, narrow channel so choose a tall pot to give them a strong start.

How to grow sweet pea plants

Sweet peas growing in frames

Put your wigwam frame in a bright position where you'll have easy access to flowers
Image: Yolanta/Shutterstock

If sowing sweet pea seeds seems like too much effort you could always get a head start by ordering sweet pea plug plants. Place them in a bright position and keep an eye out for slugs as they love the young, new shoots.

As your seedlings grow they’ll start to become tall and leggy. Encourage them to produce side shoots by pinching out the tips of the plant. Simply nip off the top of the stem with your fingers, just above a set of leaves. This will make each plant much bushier and more robust. And the more shoots there are, the more flowers the plant will produce!

How to transplant sweet pea plants

Growing a row of sweet peas

Growing a row of sweet peas for cut flowers at an allotment
Image: Peter Turner Photography/Shutterstock

In April, once your sweet peas are growing well and the main risk of frost has passed, you can pop them outside to acclimatise them to outdoor conditions for a week or so before planting them in their final position.

Plant your sweet peas out in a bright sunny spot in the garden that’s easily accessible for regular picking. Sweet peas love a rich, moist soil so dig a couple of buckets of compost into the planting area beforehand to enrich the soil and hold moisture during dry weather. Alternatively, plant sweet peas out in large containers on the patio. But wherever you decide to plant them, you’ll need to provide a suitable support as sweet peas are climbers.

Put your support frame into position before you start planting. Turn each pot out and gently separate the plants. Place 2 or 3 seedlings in each hole for a nice, full display. Aim to plant each group about 15cm apart.

How to tie in sweet pea stems

Sweet Pea Support Rings from Thompson & Morgan

Tying in your flowers will produce straight stems for cutting
Image: Thompson & Morgan

Sweet peas climb by twining their tendrils around the support frame, but it’s helpful to guide them using sweet pea support rings.

Keep an eye on your plants as they start to gallop away and keep tying them in as they grow. You’ll need to do this every 7-10 days through the entire growing season. Encouraging them to grow vertically up the frame will give you straighter stems for cut flowers.

How to care for sweet peas

Sweet Pea 'Fragrantissima' from Thompson & Morgan

Ideal for cut flowers, the more you pick the more they grow
Image: Sweet Pea 'Fragrantissima' from Thompson & Morgan

Throughout the season you’ll need to keep your flowers well watered, as dry soil makes them go to seed quicker. Once your sweet pea plants are in full flower make sure that you dead-head them and remove seed pods as soon as possible to encourage more blooms to be produced.

For a quick 'how to sow, plant and grow sweet peas' tutorial, check out this video for some top tips:

If you love having fresh cut flowers to add colour and fragrance to your home, then sweet peas are the plants for you. They’re ideal for cutting as the more blooms you harvest, the more they grow. Find more sweet peas resources over on our hub page.

Sue Sanderson T&M horticulturalist

Written by: Sue Sanderson

Plants and gardens have always been a big part of my life. I can remember helping my Dad to prick out seedlings, even before I could see over the top of the potting bench. As an adult, I trained at Writtle College where I received my degree, BSc. (Hons) Horticulture. After working in a specialist plantsman's nursery, and later, as a consulting arboriculturalist, I joined Thompson & Morgan in 2008. Initially looking after the grounds and coordinating the plant trials, I now support the web team offering horticultural advice online.

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