How do I get the most from my sweet peas?

Professional gardener, Debi Holland shares her tips for getting the best from these fabulous garden plants.

Annual sweet pea - lathyrus odoratus

Picking a posy of sweet peas for a friend is one of my favourite summer ‘jobs’. Inhaling a lungful of their sweet scent makes you feel elated. Their fragrant frilly petals, palette of tasteful colours and sublime scents seduce even the hardest of gardeners and their strong scent also attracts a wide variety of pollinators to your garden. But what’s the secret to growing stocky healthy plants and getting prolific blooms?

Choosing sweet peas

There is such an enormous range of colours and scents available. Growing from seed allows you to economically explore the huge range of different varieties and of course offers superb value for money. But you can also buy fabulous collections of ready to grow plants mail order and online and in garden centres that can be planted out (see below) and will flower prolifically in your garden all summer long. Grandiflora varieties are traditionally highly scented whereas the Spencer types are famed for long stems and large frilly flowers. Modern Grandifloras and multifloras have been bred to combine the best of both.

mixed sweet peas
There is a large range of different varieties, colours and scents available. Image: Adobe Stock

Growing sweet peas

January to April are perfect times to sow, although autumn sowing can be done between October – mid November. On dark wintry days the anticipation of growing wafts of exquisite scent can be too tempting to resist. To soak or not to soak? That is the question. There is always debate as to whether you should ‘nick’ and pre-soak your seed. Neither are essential but I personally soak my seed overnight to soften their hard coats, giving germination a head start. Sweet peas detest root disturbance so for best results grow them in root trainers, which look like long thin cells. These encourage strong, long, healthy roots allowing plenty of room to grow. When buying ready grown plants, look for those grown in deep modules, plant cells and pots where the roots have had room to develop.

Toilet roll inner tubes make perfect recycled pots; over time the roll will disintegrate after planting out. Alternatively make your own homemade eco paper pots from recycled newspaper. Cheap, quick and easy and no repotting required.

Sow sweet peas in individual modules such as these paper pots. Image: Debi Holland

Sowing seed

Sweet peas are hardy and tolerate cold temperatures. Use good quality multi-purpose compost like Richard Jackson’s Peat Free Compost, sow seed about 1cm deep and water. A cool greenhouse or cold frame is ideal. New shoots can grow too tall and leggy when sown indoors as it is often too warm.

Watch out for hungry mice! Your greenhouse could turn into a Michelin Star restaurant for the local rodent community. Sweet pea seed is a delicacy. Protect with a cloche until shoots appear. Once you have two or three true leaves, pinch out the top with your forefinger and thumb, this will encourage side shoots and stocky plants. Alternatively direct sow in April, straight where they will grow all summer.

Planting out

Plant out your young plants in spring, or if you have bought ready grown plug plants as soon as possible after arrival. Choose a sunny position with well-drained soil, prepared with nutritious organic matter such as well-rotted manure or garden compost. Place your plants in individual holes around your wigwam canes. Level the soil just below the first side shoot and firm in. Water gently after planting. Sweet peas need supports to grow up but you do not have to have a wall and trellis. Try freestanding wigwams from a garden centre or construct from willow or hazel ‘pea sticks.’ Bamboo canes can be tied together to form an ‘A’ frame or try netting. They also grow well in large containers but still need support.

You can grow sweet peas up wigwams in containers. Image: Debi Holland

Tip: For beautiful straight flower stems, cut off the tendrils as they can cling on and distort stems. For prolific long lasting blooms use a high potash feed. Richard Jackson’s Flower Power contains everything the plants need to excel. The key to a long flowering season is picking and deadheading. The more you pick the more they will grow. Deadheading is essential, otherwise the plant ‘thinks’ it has achieved its goal and will stop producing flowers!  Happy sowing and growing and look forward to a house full of fragrant sweet peas next summer.  

Sweet peas make perfect cut flowers Image: Debi Holland

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