Lathyrus: sweet pea
Height 30cm-3m (1-10ft)
Planting distance 15-25cm (6-10in)
Flowers early summer to early autumn
Well-drained, medium loam — ideally slightly alkaline
The much-loved sweet pea is a versatile plant in the garden. Grown up a wall, fence or another plant, it reaches a height of up to 3m (10ft). It can be grown up pea-sticks in the vegetable patch just for its cut. Or it can be grown without support in a mixed annual border – dwarf varieties look most effective alongside traditional cottage garden plants such as clarkias, candytuft and cornflowers.
The pea-like flowers appear in early summer and, provided all dead blooms are removed immediately, will continue until early autumn. They come in an enormous range of colours – reds, pinks, salmons, purples and white, either one colour or bi-coloured. Most are scented, some more than others.
All sweet pea varieties grown in the garden are developed from Lathyrus odoratus. To bring some order to the enormous range avail-able, they are usually organized into groups.
DWARF VARIETIES Reaching 15-90cm (6-36in) high, these sweet pea varieties can be grown without supports. Use them at the front of borders or to fill window-boxes and containers.
‘Jet Set’ has sweetly scented, frilled flowers in a wide range of colours. It reaches 90cm (3ft) high.
‘Patio’ has fragrant flowers in mixed colours with wavy petals. It grows 30-38cm (12-15in) high.
‘Supersnoop’ has waved flowers in a range of colours, carried on long stems, which make it a suitable dwarf variety for cutting. The plants are without tendrils and have a neat habit, reaching 75-90cm (2-½ – 3ft) high.
GALAXY VARIETIES These are tall vigorous growing varieties, reaching 1.8-3m (6-10ft) high. Grown for their early, long-lasting display, they produce numerous large flowers in a wide range of colours offered as ‘Galaxy Mixed’. Train them up tall supports.
OLD VARIETIES These have largely been replaced by the more robust bigger-flowered Spencer varieties. Available now only in seed mixtures (’Old-Fashioned Mixed’) they have small, dainty flowers with a strong, sweet fragrance. Train up a wall, fence, pergola, or pea-sticks – they grow 1.8-3m (6-10ft) high.
SPENCER VARIETIES These are the most commonly grown sweet peas. They usually carry four or five particularly large blooms on each stem. Reaching up to 3m (10ft) high, they look most effective grown as climbers. Catalogues list them according to colour. They are suitable for garden decoration, for cutting and for exhibition purposes. Only some have a strong fragrance.
‘Air Warden’ has strong fragrant orange-scarlet flowers.
‘Anniversary’ has soft white flowers edged with rose-pink; delicately scented.
‘Beaujolais’ has rich burgundy maroon blooms.
‘Blue Danube’ is a blue-flowered variety with frilled petals.
‘Bouquet’ is a vigorous strain available in single colours (rose, pink, white, lavender, blue) or as mixtures; strongly scented.
‘Butterfly Mixed’ has cream or white flowers marked, streaked and edged with red, pink, orange, blue or purple.
‘Charisma’ has wavy carmine-red, long-stemmed flowers.
‘Elizabeth Taylor’ has clear, rich mauve flowers.
‘Giant Waved’ has large flowers with wavy petals in a wide range of typical sweet pea colours.
‘Herald’ has deep rose-pink flowers with a hint of orange in them.
‘Hunter’s Moon’ bears sweetly scented lemon-cream flowers. ‘Leamington’ has deep lavender-blue flowers with a sweet scent.
‘Love Match’ comes in mixed colours. The flowers are bicoloured and have frilled petals.
‘Maggie May’ bears wavy-edged, strongly fragrant blooms of sky-blue flushed with white.
‘Maroon Magic’ is a scented variety, with wavy, maroon-purple flowers on long stems.
‘Mrs. R. Bolton’ has pale pink flowers resembling the colour of almond blossom.
‘Noel Sutton’ is rich blue-mauve with a strong fragrance.
‘Pennine Floss’ is a strongly-scented variety, with red-purple wavy flowers.
‘Princess Elizabeth’ has cream to salmon-pink flowers.
‘Red Ensign’ is strong-growing, with scented, deep scarlet flowers.
‘Romance’ is a bicoloured seed mixture, producing frilled and scented flowers in a range of colours.
‘Rosy Frills’ has white flowers with frilled petals edged deep rose-pink.
‘White Supreme’ has strongly scented, pure white flowers.
‘Winston Churchill’ has rich crimson-red flowers with frilled petals.
‘World’s Children’ is free-flowering, with long-stemmed flowers bicoloured in fiery red and orange.
‘Xenia Field’ is delicately blush-pink on cream ground, shading to apple-blossom pink.
Many sweet pea varieties have seeds with thick coats, so it pays to nick them with a sharp knife or soak them in water for 12 hours to speed up germination.
Sow the seeds in boxes or pans of seed compost in early autumn or early spring at a temperature of 16°C (61°F). Pot the seedlings into 7.5cm (3in) pots of potting compost. When they reach 10cm (4in) high, pinch out the growing tips to encourage strong sideshoots. Harden off in a cold frame before planting out – autumn-sown ones in mid-spring, early spring-sown ones in late spring.
The seeds can be sown directly in the flowering site in early to mid autumn or early spring, and then thinned to 15cm (6in) in. An autumn sowing gives the best results, but young plants have to be protected with cloches in cold areas. Remove the cloches in mid spring.
Sweet peas will grow in any ordinary gardenin a sunny site. But for the best results plant them in deeply dug, well-manured and well-drained, slightly alkaline loam.
Dead-head and remove any seed pods so flowering continues until early autumn.
Pests and diseases
Mildew may occur on the leaves and stems and wilt may cause the leaves to turn yellow and the plants to wilt. Virus diseases can be a problem.