Texas Cooperative Extension,
Texas A&M University, College Station, Texas

March 2007


Sweet Peas


by the National Garden Bureau

Sweet pea 'Ocean Foam'
'Ocean Foam' sweet pea

North America’s enchantment with sweet peas goes back more than a century. In the 1930’s box cars of sweet pea seeds were shipped from California producers to their customers east of the Rockies. The love of this fragrant garden climber was widespread in North America from farms of the plains to country gardens in the northeastern United States.

English gardeners call sweet peas "the Queen of Annuals." These charming annuals are unique among garden flowers with their vivid colors, fragrance, and length of bloom in the garden. The flowers have an air of romance about them in both their scent and appearance. Sweet peas’ fragrance is sensuous, a captivating blend of honey and orange blossom, with an intensity that varies from one cultivar to another. The ruffled blooms look like little butterflies all aflutter. Sweet peas offer one of the widest color ranges in the plant kingdom, including crimson reds, navy blues, pastel lavenders, pinks, and the purest whites. These colors are found as solid colors, bicolors, and streaked or flaked flowers.

Put it all together - fragrance and color - in a climbing plant with voluptuous clusters of flowers and it becomes obvious why sweet peas are such a favorite among gardeners and non-gardeners alike. The fact that they are long-lasting cut flowers is the icing on the cake. Several stems in a plain vase make a lovely country-style bouquet.

Sweet peas can adapt to any garden style. They are excellent in a cutting garden, ensuring a bounty of flowers to enjoy indoors. The loose, billowing form of bush varieties makes them a natural in a cottage garden. Sweet peas can take on a more formal or casual look when they are growing up a support. Give them a trellis or fence - white picket, post and rail, or even chain link - sweet peas have an informal panache. Yet, train them on a tuteur and they exhibit all the class necessary for any formal garden. Arbors and trellises - available in so many styles - are perfect foils for sweet peas’ adaptability.

Sweet pea 'Cupani'
'Cupani' sweet pea
Finding the right season to grow sweet peas will enable any gardener to enjoy their scented blooms. Sweet peas can take frost as they develop. So in North America, gardeners can enjoy these bloomers from early spring onward. Ideally, gardeners want to take full advantage of spring color by sowing seed in the fall in southern states and early spring in northern regions. With protection from intense afternoon heat and proper mulching, the blooming season of sweet peas can be greatly extended.

HISTORY

Interestingly, the origin of the sweet pea in the wild has been greatly disputed. The first written record appeared in 1695. Francisco Cupani, a member of the order of St. Francis, noted seeing sweet peas in Sicily. There is no documentation of whether the sighting was in the wild or in the botanical garden in the village of Misilmeri (near Palermo) that was under his charge. It was not until 1699 that Cupani passed on the seeds of the enticingly fragrant, small bicolor flowers (blue and purple) to Dr. Casper Commelin, a botanist at the medical school in Amsterdam. In 1701, Commelin published an article on sweet peas, which included the first botanical illustration.

Historians presume that Cupani also sent seeds to Dr. Robert Uvedale - a teacher and aficionado of unusual and new plants - in Middlesex, England at the same time as he sent them to Amsterdam. This assumption is based on a herbarium specimen that Dr. Leonard Plukenet made in 1700, noting the plant’s origin as Dr. Uvedale’s garden.

Although the exact origin of the sweet pea is uncertain, the original Cupani variety, a bicolor with purple upper petal and deep blue winged petals, is available to gardeners still under the name Cupani! Origins aside, a hundred years after their "discovery" there were only six colors available in Europe until the mid 1800’s. Finally, near the close of the 19th century, sales took off. In England, Henry Eckford, who hybridized and selected sweet peas for their best characteristics, introduced the Grandifloras, which revolutionized sweet peas. They were larger, with more color choices and had a lovelier form than the typical sweet pea. Twenty-three Eckford varieties are still available to gardeners today from Bodger Seeds in California who sells them to seed packet companies as separate colors and in fashionable mixes. Theme blends of these striking flowers include all blue shades - 'Ocean Foam' and 'Jewels of Albion;' red and pink blends- 'Red Rover' and 'Queen of Hearts;' and deep rich combinations - 'Queen of the Night.'

In 1901, Silas Cole, head gardener to the Earl of Spencer, found a natural mutation in the garden under his care, which he named Spencer’s. The Spencer type became very popular because of its ruffled standard (the upper petal) and long wing (lower petals) that resulted in larger, more flamboyant blooms. They were late flowering varieties, which did not matter when grown in the cool English climate. Spencer types were also improved for the number of flowers produced per stem and were thus called "multiflora." There are many Spencer sweet pea colors available for gardeners today. The Spencer flowers remain very popular in England and Europe.

Sweet pea 'Streamer's Mix'
'Streamer's Mix' sweet pea
There are many American seed companies that contributed to the advancement of sweet peas. Three American bred varieties from the early twentieth century remain popular today and are still in commerce. They are the long vine 'Royal' separate colors and ‘Royal Family Mix,' the shorter vine 'Knee-Hi Mix' and the very compact 'Little Sweetheart Mix.' California breeding of sweet peas has focused on developing extremely early flowering and non-tendril types. Mr. Yosh Arimitsu of Bodger Seeds Ltd. selected a series of sweet peas to be extremely early under long day or short day growing conditions, to have flower stems longer than 17 inches, and to produce extra large flowers on stems with 5 to 7 flowers. There are numerous improved qualities in the 'Elegance' series bred by Bodger Seeds Ltd.

There has also been work done in non-tendril sweet peas. Typically, sweet peas have two leaves and two tendrils that cling and assist vines as they climb toward the sky. In non-tendril lines, the tendrils develop into true leaves and, thus, plants have four leaves per stem. Non-tendril varieties have shorter vines and are excellent for bedding use. Mr. David Lemon did the original non-tendril work at Denholm Seeds with the creation of 'Snoopea Mix' and later at Bodger Seeds with 'Explorer Mix,' winner of the RHS Award of Garden Merit.

Compact container sweet peas have a long history. 'Cupid' varieties were popular in the early 1900’s and, at one time, greater than 30 varieties were available. With the growth of interest in container gardening, 'Cupid' lines have again become favorites of North American gardeners. ‘Cupids’ can be grown in window boxes, hanging baskets and containers. In recent years, New Zealand has also been a source of new sweet pea varieties, especially the breeding of Dr. Keith Hammett. He made great strides in the development of new color patterns, short day flowering, and a focus on fragrance. 'Streamers Mix' and 'Saltwater Taffy' are Hammett's creations containing all striped varieties in a single mix. 'Streamers Mix' is composed of many striped varieties, including chocolate/white, blue/white, orange/white, red/white stripes and shades between.

FRAGRANCE

There is a great deal of variation in the fragrance and intensity of smell in sweet peas. Since the odor that our noses detect is from a complex combination of volatile chemicals produced within the flowers, the strength of fragrance of a sweet pea variety can change due to a number of factors, such as rain, high temperatures, time of day and the age of the flower.

Certainly, some of the older varieties from the Eckford lines are the most reliably fragrant sweet peas. They are blended together in mixtures called 'Old Spice Mix' and 'Perfume Delight.' Dr. Hammett has begun work on a number of selections that are especially fragrant. These varieties are available with names like 'High Scent,' 'April in Paris' and 'Renaissance.'

NOMENCLATURE

The moniker, "sweet pea," was supposedly first used by the poet Keats in the early 1800s. Both English and North Americans use the common name, "sweet pea."

This text has focused on Lathyrus odoratus, common name sweet pea, but there are a number of other Lathyrus species worth mentioning. They include the perennial Lathyrus latifolius, available in four colors and a mix. This cold hardy perennial is suitable to USDA temperature Zone 5. Lathyrus sativus produces lovely small gentian blue flowers, while Lathyrus chloranthus has yellow flowers. This last species has been used, thus far unsuccessfully, in inter-species breeding attempts to bring the elusive yellow flower into the commercial L. odoratus. All three of these species mentioned above are commercially available in North America. Within the genus Lathyrus, there are 110 species and innumerable cultivars. In broad terms, the genus is commonly known as vetchling or wild pea. It is in the Leguminosae (a.k.a. Fabaceae) or Legume family. Other legumes include garden peas, acacia, beans, mimosa, redbud, soybeans, wisteria, and clover.

With the growing interest in edible flowers, it is very important to be specific with the name. Although garden peas, (Pisum sativum) such as English peas, edible podded peas and snow peas are edible, sweet peas (Lathyrus odoratus) are poisonous - especially the flowers and seeds.

CLASSIFICATION

There are four ways to classify sweet peas. They are habit, flower form, fragrance, or day length response. Plant habit can be climbing; tendrils wind around a support and can grow 6 to 10 feet depending upon the growing conditions and cultivar. The plant habit can be compact reaching only 8 to 24 inches tall and needing no support. Avid gardeners select the site first, and then determine the best variety with the desired habit for that site or container.

The sweet pea flower form can be single, double, or semi-double. The flower diagram shows the anatomical names of the flower parts. The flowers can be fragrant. If this is important, look for those that are labeled fragrant.

Many plants initiate buds or flowers under certain day length. These are called short day or long day flowering plants. Most sweet pea cultivars need lengthening days to initiate buds and bloom. This means growing sweet pea plants after March 21 as day length increases. In the southern regions of North America, sowing sweet peas in the fall requires cultivars that are "short day flowering" due to the shorter day length of fall and winter. There are cultivars that fit this cultural requirement such as 'Elegance' series.


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