Sweet peas (Lathyrus odoratus) are easily grown annuals and are usually grown from seed in early spring, or earlier indoors. They can also be started in the autumn for planting out in spring or sown direct where they are to flower. They are hardy plants but the seedlings will benefit from the protection of a cold frame in severe weather. There are many varieties and mixes to choose from, and packets of seed are readily available. The seeds can be soaked or nicked before sowing and the seedlings should be pinched at an early stage to encourage side shoots and root development.
Sweet peas will require support, they are commonly grown on bamboo or twig tripods, trellises or canes in rows, or they can be planted to climb through other plants, much like clematis. They have tendrils which they use to attach to the supports, but you will need to initially tie the stems to the supports. The supports should be constructed when the seeds are sown or transplanted to avoid disturbance later on. They will grow up to 6 to 9 feet. A rich soil is best and they like sun. Feeding with a suitable fertilizer such as for tomatoes and an ample water supply are necessary for producing the best flowers.
Once the plants start to produce flowers (any very early ones should be removed to let the plants make a good root system and become well established), the blooms should be regularly cut as this helps promote more blooms. At all costs the plants must be prevented from setting seed as this will greatly reduce the amount of flowers produced. Sweet peas are one of the most delightful cut flowers and provide wonderful long lasting blooms in the vase.
Sweet peas come in numerous colours, mainly white, pink, red, lavender, pale blue, maroon and cream, and there are bi-colours and some with stripes or speckles. Dwarf plants are also available for gardeners with limited space, these can be grown in containers.
Not all varieties of sweet peas are scented so if you want to grow the scented ones (and to not is to miss out on the greatest charm of the plant), make sure you select a variety with a good fragrance. This should be noted on the seed packet.
Good scented varieties include
'Albutt Blue' - highly scented pale blue picotee
'America' - a red and white striped heirloom variety
'Antique Fantasy' mix - vigorous old fashioned variety
'Blue Ripple' - pale blue with strong fragrance
'Charles Unwin' - sweetly scented amber pink
'Chatsworth' - lavender blue award winner
'Jilly' - cream/ivory scented blooms - exhibition favourite
'Royal Wedding' - vigorous long stemmed white
'Wiltshire Ripple' - white rippled with maroon
The plants can also be integrated into a perennial border, using a tripod or obelisk support they should be planted close to a path so you can have access to the flowers to keep cutting throughout the growing season, (or to dead head the plants) and also to enjoy the scent. They should last throughout the summer and even into early fall.
All photographs in the article are my own.