Ightham Mote's top tips for sweet peas.

Pippa Coulthard, Gardener, Ightham Mote Pippa Coulthard Gardener, Ightham Mote
56 canes of sweet peas line each side of the pathway, with lavender underplanted in the Cutting Garden

The sweet pea walk through the Cutting Garden at Ightham Mote is a feast for the senses. The intoxicating scent is a highlight of summer, and is a favourite with our staff, volunteers and visitors.

We enjoy talking about our work, but have noticed that we're often asked the same questions:

"My sweet peas never look this good...My plants are nowhere near as tall as these... My flowers usually have such short stems… My flower stems are twisted…"

As we're asked these questions so often, we thought it was about time we shared our top tips with you for how we like to grow our sweet peas. But please remember, there is no 'right' way of growing them, we grow ours using an historic method, but others may not use it as it takes so long.  


Our top tips for growing sweet peas

Trays of seedlings in the plant polytunnel

1. Planting from seed

If you're able to grow from seed, you'll have a wider choice (currently, the National Collection has more than 1300 varieties). For the strongest plants, many growers say you should sow seeds in October / November, but we don’t have room for this, so we sow seeds in January / February. Our criteria is scent… we don’t grow for competition, but to continue the garden favourite of a previous owner, Sir Thomas Colyer-Fergusson. Even if you don’t have the luxury of growing from seed, you can get plants in the garden centres in spring.

Trays of plants sit outside to 'harden off' before planting

2. Hardening off

This is an area that is often overlooked. If your Sweet Peas are started in a greenhouse, then they need to be gently introduced to the cooler temperatures outside. Unless you have a cold-frame, wait until the frosts have gone and put them outside during the day, and bring them in at night. Yes, it may be frustrating, especially when you're in a rush, but you'll have a stronger plant and you’ll get flowers earlier.

A side shoot growing from the base of a sweet pea plant

3. Remove the side shoots

Pick the strongest stem, and concentrate on this. As side shoots develop they spread the energy, which may result in shorter stems and a smaller number of flowers. Having planted the sweet peas out in late April / May they will start flowering in late May / early June. We check the plants twice a week, continuing to remove side shoots and tendrils as they develop. We’ve found that if we pinch out by hand, the shoots don’t re-grow, whereas if we cut them, they often regrow. This may be purely coincidental, but it’s quicker anyway.

The growing tip of the sweet pea is protected against the cane

4. Guard the tip

Any damage to this and your plant is finished!

Sweet peas tied to the canes, making sure leaf joints aren't squashed

5. Training

Just as the plants near 1ft (30cm) tall, we start tying the stems to canes. Make sure you don’t squash the main stem against the cane, and tie just below the joint. This way, when the flower grows from the joint its stem is supported and should grow straight.

Tendrils at end of leaves of a sweet pea

6. Remove the tendrils

The tendrils are used for climbing, and will wrap around anything for support. As we tie our sweet peas to canes, we remove the tendrils so they can’t wrap around the flower stems and bend them.

Gardeners tying garden canes into long rows either side of a path for sweet peas to grow up them

7. Planting out

We cordon train our sweet peas up 8ft (2.4m) canes, spaced 8-10 inches (20 – 25cm) apart, with one plant to a cane. We obviously aim to have many more plants than canes so that we can discard any that aren’t up to standard.

Sweet pea plant stems laying along ground

8. Laying sweet peas

When the plant reaches the top of the cane, there’s nowhere else to go. We don’t want to remove the growing tip, as this is the only growing tip when cordon training - if we remove this tip, there will be no more sweet peas. We carefully untie each of the stems, and lay them along the ground before tieing them to another cane with the growing tip about 2ft (60cm) above the ground. The plants can then continue to grow and provide you with flowers.

Sweet peas in a vase

9. Keep cutting the flowers

Annual sweet peas only flower to make seeds – they don’t care if you like admiring the flowers, when they go to seed, that’s their job done and the plant will die. We cut the flowers twice a week to go into the house. We usually have flowers from June until September / October (depending on the weather). However, the older the plant gets, the shorter, and smaller the flowers – but we think they’re still a beautiful feature.