View source for Sweet Pea

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Sweet Pea. The popular name of Lathyrus odoratus, one of the Leguminosae, grown for its handsome and fragrant flowers. See Lathyrus for botanical account; for structure of the flower, see Legume; see also Orobus.

Because of its range of color, beauty of form, fragrance, and value as cut-flowers, the sweet pea is not only the queen of the large genus to which it belongs, but now ranks first among annual flowers. It has been long cultivated in gardens, and in recent years in America it has risen to a place among the five leading commercial cut-flowers.

The sweet pea is a native of the island of Sicily and was first described by Father Franciscus Cupani, a devout Italian monk and an enthusiastic botanist, in a small work published at Panormi in 1695. Cupani sent seeds in 1699 to Dr. Uvedale at Enfield, England, and to Caspar Commelin at Amsterdam, Holland. The latter published a figure, and description of the plant in his "Horti-Medici Amstelodamensis" (1697-1701). From this description it is learned that the flowers had purple standards and sky-blue wings, were fragrant, and that the plants were climbing in habit, as they grew to a height of 6 or 7 feet. A white-flowered variety of the sweet pea appears to have been known in 1718, and in 1737 Burmann called attention to the pink-and-white-flowered form. Although he admitted that his plant differed only in the color of the flowers from that described by Cupani, and which, he says, occurred frequently in gardens, Burmann proceeded to make a new species, Lathyrus zeylanicus, because he received the seeds among a collection of plants from Ceylon. Later botanists have not found the sweet pea growing wild in Ceylon, from which the authorities conclude that a mistake was made. This form was named Painted Lady and was grown until about 1900, when it gave way to its improved form, Blanche Ferry.

Sweet pea seeds were offered for sale as early as 1724. The three colors mentioned appear to have been the only cultivated varieties until 1793, when the black and scarlet varieties were catalogued. In 1837 the first striped variety, in 1860 a yellow-flowered and also the Blue Edged varieties, were offered. The latter was white with a distinct blue edge. Later this form was known as Butterfly, and it was the forerunner of the Picotee section. In 1865 Invincible Scarlet won the first certificate awarded a new sweet pea. Crown Princess of Prussia, the first of light pink varieties, was offered in Germany in 1868. Adonis (1882) was the first of the rose-pink varieties. Until 1880 (a period of 185 years) little improvement had been made in the sweet pea, and it had not been given the attention that had been bestowed upon the dahlia, verbena, hollyhock, or the rose. There were nine distinct varieties in 1860, and although many new names appeared during the next twenty years, these mainly represented supposed improved strains of the existing colors. It is very probable that not more than fifteen distinct varieties of sweet peas existed when Henry Eckford, the great specialist, began his remarkable work.

No one can understand the improvement in sweet peas within the last forty years unless one considers the form of the flowers as well as the limited number of colors which then existed. The oldest illustrations of the sweet pea show the wings to be more prominent than the standard, and although there appears to have been some improvement in the size of the standard before 1875, nevertheless the flower was lacking in many respects. The standards of most of the varieties had a tendency to reflex at the edges, and the apical notch was very prominent. Often there were side notches which caused the standard to droop forward. The natural line of improvement, aside from securing better colors or color combinations, was to round out the outline of the standard and to give it a more expanded form and greater substance.

Eckford, after long experience and signal success as a breeder of florists' flowers, began his work on the sweet pea about 1876. Beginning with a few varieties, he patiently crossed and selected for several years before he began to secure results. His first notable variety, Bronze Prince, was awarded a first-class certificate by the Royal Horticultural Society in 1882. Soon he began to secure new colors and sent out the deep bronze-blue Indigo King (1885), Orange Prince (1886) and the dark maroon Boreatton (1887). These were followed each year by new colors and improved forms of the flowers. The hooded varieties appeared and gave a new interest to sweet pea improvement. Although many of the hooded varieties that were introduced had flowers in which the standards were hooded so much as to appear triangular in outline, nevertheless many were very beautiful. The perfection of this form was reached in the variety Dorothy Eckford (1903). The increased size of many of Eckford's varieties led to the name Grandiflora sweet peas, but this name is now used to designate all varieties which do not have flowers of the waved or "Spencer" form.

At the time of the great bicentenary conference on the sweet pea held in London in 1900, Eckford had introduced 115 out of the 264 varieties catalogued up to that time. Even in America the Eckford varieties constituted at least 60 per cent of all lists of selected varieties; and in 1916 of the Grandiflora varieties remaining in the trade, as shown by the catalogue of the leading American dealer, more than one-half originated in Eckford's garden at Wem, in Shropshire.

Improvement in America.

The real interest in sweet peas in America began soon after the first introduction of the Eckford varieties by Breck and by Henderson in 1886. Added impetus was given by the introduction of Blanche Ferry in 1889, and by Emily Henderson in 1893. As early as 1890 the sweet pea had become a popular flower in this country, and soon local sweet pea shows were held. The demand for seed greatly increased and the competition in the shows was keen enough to bring about a desire for new and better varieties. The growers looked forward with anticipation for Eckford's annual set of novelties. Meanwhile in England there was not yet the keen interest in sweet pea that had taken hold of America. The popularity of the sweet pea in America was Eckford's constant inspiration to better things, but gradually England came more generally to appreciate this flower with the result that since the waved form appeared the sweet pea has surpassed the popularity it attained in America. The demand for seed was satisfied when it was found that California had superior advantages for seed production. When the Eckford novelties were grown in California they sometimes proved to be unfixed, and some of these variations, together with the results of some artificial crossing, gave the growers some new varieties. Many of the best striped, as well as marbled varieties, are of American introduction.

The most striking novelty in sweet peas, the dwarf or cupid race, was found in California in 1893 and was offered to the seed trade under the name Cupid in 1895. The first variety was white-flowered. This was followed by other varieties, and soon all the colors then known in sweet peas were to be found in the dwarf type. The Cupid sweet pea grows only a few inches high, forming a dense mass. The dwarfing is the result of the extreme reduction in the length of the internodes of stems. The flowers were of the open and hooded form, borne upon short stems, and characterized by little or no fragrance. They appear to thrive under more drought and heat than the ordinary type. They have not succeeded very well outside of California, for in a season of normal rainfall in the East the plants are injured by lying on the moist ground. The appearance of the dwarf sweet pea offers perhaps the best example of synchronous variation on record. This remarkable variation appeared in California, Germany, England, and France within the period of two years prior to its announcement here by Burpee.

The Cupids were followed by the bush varieties which were considered to be intermediate in growth. This class did not gain much favor and soon disappeared. The snapdragon varieties, which had the standard reduced in size and in contact with the wings, giving the blossom the general effect of a snapdragon, were offered in 1897 but attracted little attention.

The winter-flowering type is the most important of all those originating in America. This type has been perfected in this country and has tremendously enhanced the financial value of the sweet pea as a cut-flower. No other country can begin to approximate the extent of the industry of sweet pea growing under glass.

Development of the waved varieties. (Fig. 3745.)

At the time of the bicentenary of the sweet pea, it seemed as if the future improvement of the sweet pea would be along the line of an increase in the number of flowers to a spike or the securing of new colors or color combinations in the existing open and hooded forms of the flower. No one seemed to realize that the sweet pea was on the eve of the most remarkable improvement in the form of flower and that along with it would come increased size and a greater average number of flowers to a spike. This was the introduction of the waved or, as it is called in America, the Spencer type, in 1904. The first variety was raised by Silas Cole who named it Countess Spencer in honor of the wife of his employer. The parentage of this variety, although doubted by some, has been given as (Lovely x Triumph, 1898 ) x Prima Donna, 1899. It was shown at various English shows for three years prior to its introduction. Countess Spencer was such an improvement in size, and the form so distinctly new, that it created a sensation. The very large standard and wings were beautifully frilled and waved. The clear pink color was also especially pleasing. This variety was not entirely fixed when it was sent out and soon numerous sports were offered. Among the first of these were the orange-pink Helen Lewis and the carmine-rose John Ingman. Especial difficulty was experienced when the seed of new waved varieties was grown in California, but from this tendency to sport have been secured many of the finest varieties.

About the time that the Countess Spencer appeared, W. J. Unwin found a sport in the variety Prima Donna which he named Gladys Unwin. It was also of the waved type of about the same shade of pink as Countess Spencer, but the flowers were not so large. Soon other varieties appeared, and for a few years this group vied with the Spencer varieties for popular favor.

The introduction of the waved form aroused great interest and soon large numbers were growing sweet peas for exhibition. Many took up the production of new varieties, and soon new forms were offered in large numbers. In some cases the same sport had been found and given different names. It was seen that hopeless confusion would result if some means were not found to eliminate the synonyms. The English Sweet Pea Society established trial grounds, and when the American Sweet Pea Society was organized in 1909 it established trial grounds in cooperation with the Department of Floriculture of the New York State College of Agriculture at Cornell University, Ithaca, New York. These two national societies hold annual exhibitions, and the American Sweet Pea Society holds exhibitions of winter-flowering varieties at the National Flower Shows held each spring.

Classification.

More than 1,000 varieties of sweet peas have been introduced, but some of these represent strains of existing varieties or were applied to seedlings which did not present any improvement.

The modern sweet pea may be classified as follows: Climbing and dwarf types, the former being subdivided into garden and winter-flowering types. The varieties may be classified as to the form of the flower into open, hooded and waved forms (Fig. 3746).

Garden type Winter-flowering type Dwarf type (Cupid)
Open form Open form Open form
Hooded form Hooded form Hooded form
Waved form Waved form

The open form may be further separated into notched and rounded standards; the hooded varieties according to the degree of hooding, the most extreme case being the snapdragon varieties; and the waved varieties may be classified according to the degree of waviness as it appeared to be less or greater than Countess Spencer. This latter classification would require that the flowers be taken from plants under uniform conditions of growth. The National Sweet Pea Society of England classifies sweet peas according to form of the flower into grandiflora or waved, and into thirty-seven color sections as follows: Bicolor; Bicolor (Dark); Light Blue; Dark Blue; Blush-Pink; Lilac-Blush; Carmine; Cerise (Pale); Cerise (Dark); Cream, Buff, and Ivory; Cream-Pink (Pale); Cream-Pink (Deep); Crimson; Fancy: Lavender; Lavender (Pale); Lilac; Magenta; Marbled and Watered; Maroon; Maroon-Red; Mauve (Pale); Mauve (Dark): Orange-Pink; Orange-Scarlet; Picotee-edged (Cream Ground); Picotee-edged (White Ground); Pink (Pale); Pink (Deep); Rose; Salmon; Salmon (Pink): Scarlet; Striped and Flaked (Purple and Blue); Striped and Flaked (Chocolate on Gray Ground); Striped and Flaked (Red and Rose); White.

The bright sunshine and summer heat of America tends to destroy some of these fine distinctions of color, and the varieties can be grouped in about twenty-five color sections.

Garden culture.

One of the first essentials in sweet pea culture is the choice of an open sunny location, thus providing plenty of light and air. Plants grown in too much shade are weak and spindling in growth, producing few flowers. Any ordinary garden soil is suitable for sweet peas, provided it is sufficiently drained so that in periods of excessive rains the water will not lie on the surface, causing the plants to become yellow and the roots to decay. A heavy soil usually gives better results than a light one as it holds moisture better.

A preparation of the soil as is usually made for the growing of vegetables will give fairly good results; but extra care in the selection and preparation of the soil will be repaid in larger flowers, longer stems, better colors, and a longer blooming-period.

The sweet pea is a deep-rooting plant, and in order to provide suitable conditions so that the effects of drought are overcome, the preparation must be deep and thorough. Deep preparation not only promotes available fertility, but also increases the area in which moisture and nourishment may be found, and the plant responds by sending feeding-roots in all directions.

The preparation of the soil should be made in autumn by trenching at least 2 feet in depth. Since this is an expensive operation, it is advisable instead to dig a trench 16 inches wide and 2 feet deep for each row of peas. If the subsoil is poor or of unsuitable character, it should be removed and replaced with good soil. If the subsoil is very heavy, coarse stable-manure should be mixed with it. A good dusting of air-slaked lime, applied while working the soil in the autumn, is very beneficial. Many soils that have been cultivated for a long time are acid, so that leguminous plants, such as clover or sweet peas, will not grow, or at least do not thrive. Lime corrects this acid condition and, furthermore, it releases plant-food that would not otherwise be available in soils which are not acid. Clay soils are made more open and porous by the use of lime. Half-decayed stable-manure should be mixed with the top soil. Bone-meal applied at the rate of one-quarter to one-half pound to a lineal yard of trench will prove beneficial. The trenches should be filled more than level full, and left rough. During the winter the soil settles, but if in spring the ridges can yet be seen, it will be found that these dry rapidly and thus favor early planting.

Sweet peas for the garden are either sown where the plants are to be grown or are sown in pots and transplanted. Sowing in the open ground may be done either in autumn or spring. South of the latitude of New York, sweet peas may be successfully grown from fall sowings. North of this line the practice is not always successful unless they are planted in a well-drained situation in a sandy loam. The general conditions requisite to success are to plant late so that the seed does not germinate and appear above the surface. If any top growth is made, the plants will be killed in sections where the ground freezes. The rows should be slightly ridged up to prevent water standing over the row. After the ground freezes, a mulch of manure is applied. Fall-sown sweet peas bloom ten days to two weeks earlier than the spring-sown, and usually produce better flowers.

Sweet peas planted in the spring should be sown early. As soon as the soil is dry enough, the rows should be sown over the trenches prepared in the fall. If the ridges remain, they will dry earlier than level soil. These may be raked level and a drill opened so that the seed may be sown 2 inches deep and 2 inches apart. After the plants have started, but before they begin to stool, they should be thinned so that the plants stand 3 to 4 inches apart. As soon as the tendrils appear, small twigs should be thrust in the ground to support the plants and prevent their injury by the wind.

Sweet peas may be sown in 3- to 4-inch pots (Fig. 3747). A suitable potting-soil made of well-rotted sod, with a little leaf-mold and sand, is best. Four or five seeds are sown in each pot and covered with an inch of clean sand. The sowing should be made six to eight weeks prior to the usual time sweet peas can be sown. The pots are placed in a cool greenhouse or a well-protected coldframe and given plenty of light and air so as to keep the plants short and sturdy. When the plants begin to produce tendrils, insert some small twigs in the pots to support the plants. The plants are gradually "hardened off" so that they may be set out in the open ground. One great advantage of this system is that the grower is independent, to a certain extent, of weather conditions as he can wait until the soil is in the best possible condition before planting. The pots may be set 12 to 18 inches apart, using care to keep the ball of earth intact and without interfering with the supports. Good twiggy brush will make the best supports for sweet peas, but when not obtainable, wire netting makes an excellent support. The latter is durable and looks neater when not covered with vines.

The soil should be frequently stirred, and in hot weather a mulch of straw or lawn-clippings will serve to conserve moisture. If waterings are given in dry weather, they should be copious. The quality of the flowers may be improved by watering with weak manure water, but other liquid fertilizers are seldom used. The prompt removal of all withered flowers and pods is essential in preserving a long period of bloom.

Sweet peas in greenhouses (Figs. 3748, 3749).

The winter-flowering varieties are the most important type yet developed from the garden form, and this type has attained its greatest perfection in the United States. This range of sweet peas is distinct in habit of growth and early-flowering character. Unlike the garden type which apparently ceases growing for a time when the plants are a few inches high while the side shoots develop, the winter-flowering sweet peas grow rapidly until they attain a height of 2 to 4 feet. Then they begin to flower freely, after which time side branches are developed. Winter-flowering varieties planted in September begin to flower between Thanksgiving and Christmas, while varieties of the garden type planted at the same time do not flower until April or May. A knowledge of these characteristics of the early stage of growth will enable a grower to guard against considerable loss from getting the wrong seed.

Soon after the introduction of Blanche Ferry, florists began to grow that variety in boxes placed across the ends of the greenhouse where the plants were near the glass, or small clumps were grown on carnation benches and trained round the purlin posts. With such methods of culture, and with the varieties then available, the flowers were not received on the market in sufficient quantity to be quoted until March or April.

Anton C. Zvolanek, in 1892, found a chance seedling among the variety Lottie Eckford which was much earlier and dwarfer in habit. This was later crossed with Blanche Ferry, and the result of this line of crossing was the variety Christmas Pink, sent out in 1899. Miss Florence E. Denzer, a white variety, was introduced in 1902. Since the latter date many varieties have been sent out. The first varieties had flowers of the open or hooded form, but as soon as the waved sweet peas were introduced, Zvolanek made crosses with the winter-flowering varieties. It was not until 1912 that this class was ready to introduce to the trade, but in 1913 twelve varieties were offered. At present waved varieties of all the colors known among winter-flowering sweet peas are grown, and the older varieties are rapidly disappearing in the competition.

Another group of the early-flowering sweet peas is the Telemly, originated in Algeria in 1900. These varieties are an adaptation of the climate of northern Africa where the varieties of the garden type planted in the latter part of September do not flower until May. An exception to this was Blanche Ferry which flowered about the first of April. An early sport was found flowering in February, and from this have been developed a number of varieties which flower from Christmas until after the garden varieties come into bloom. Recently waved-flowered varieties have been developed by Arkwright, the originator of this strain. This group is better known in Australia or England, and in the latter country these varieties are grown to some extent in winter under glass.

The culture of sweet peas under glass has increased rapidly since 1902, when William Sim began to grow this flower extensively and has developed the modern methods. Today large greenhouses are specially constructed for the purpose of growing this flower, and the amount thus invested represents considerable capital.

Low or dark greenhouses are not suitable for raising sweet peas. Large, wide houses with side walls at least 6 feet high and with good top and side ventilation, are now built for sweet-pea growing. No beds or benches are required. If the soil in the greenhouse is not naturally good, it is removed to a depth of 2 or 3 feet and replaced with better earth. The soil is trenched 2 feet deep or deep trenches are dug in which to place composted soil in preparing to sow sweet peas. The soil should be made sweet by the addition of lime, and enriched by liberal applications of bone-meal. Each year the soil should be deeply prepared and manure worked into it before sowing.

The colors most in demand on the market are pink and white, pink, lavender and white. The reds and orange colors are usually grown in less quantity. The varieties chosen should be those possessing good, clear, well-defined colors. The Grandiflora varieties are more productive, but do not bring so good a price in the larger cities as the waved varieties.

The early crop is sown about August 15, and the later crop during the latter half of September. The seeds are sown in drills where the plants are to stand, except the white-seeded varieties which are sown in sand and transplanted. The latter do not germinate well in soil, as a rule, but when treated in this way a good stand is secured. When the rows run east and west they should be 5 feet apart, and if they run north and south they may be placed as close as 3 feet.

The plants should be thinned to four plants to a lineal foot of row whether grown in single or double drills, and in planting from pots this rule should be observed.

Sweet peas are often grown after chrysanthemums, and for this purpose the plants should be started in 2 1/2-inch pots. Two seeds may be planted in deep rose pots or in paper pots. The soil should be fibrous loam with the addition of fine old manure and sharp sand. The seeds are covered 1 inch deep, and the pots placed in a temperature of 55° to 60° F. for germination, after which the plants must be placed in a lower temperature to prevent them from becoming drawn.

The plants must soon have supports, and the best material to use under glass is string. If the rows are in line with the purlin posts, binder twine can be stretched from post to post on either side of the row thus inclosing the plants. These tiers of string will need to be as close as 6 to 8 inches at the bottom, but later as the vines grow may be as much as a foot apart. When the purlin posts are not in the row, temporary posts of iron pipe or 2- by 2-inch strips may be used. Wire netting is generally condemned by commercial growers, owing to the labor and expense connected with its erection and removal, and also because they think more crooked-stemmed flowers result. The vines supported by string can be easily removed at a minimum expense and the house quickly made ready for another crop.

The temperature in the autumn is often too high for sweet peas, and under such conditions the plants often show a tendency to flower when only 2 feet high; but, as a rule, it is usually better to remove all such flowers until the plants gain more strength. As far as possible, the night temperature should be from 40° to 45°, for if a higher temperature is given, the plants flower too soon and before they have made a good root-system. When the plants are from 30 inches to 4 feet high and showing buds, the temperature should be gradually raised to 52°. This is the highest temperature required for the Grandiflora varieties. When in bloom, the temperature should be 60° on cloudy days, and 68° on bright ones. The waved, or orchid-flowering, varieties require the same treatment previous to flowering, after which the night temperature should be 55°, 60° to 65° on cloudy, and 70° to 72° on sunny days.

Picking and packing.

Sweet pea flowers should be picked when the top flower is at least half open, unless the flowers are to be shipped a long distance, when they may be cut in a less fully developed state. The proper time to cut the flowers is in the morning, although this will depend upon the time the shipments can be made. The flowers should be kept two to three hours in water before packing, and this will govern the hour of picking for the florist. The flowers must be packed dry, and if the outdoor flowers must be picked wet, they should be placed while in water in a warm current of air to dry the blooms. The flowers are made into bunches of nineteen to twenty-six spikes, according to quality. These are tied near the base of the stems, which are wrapped with waxed paper. The bunches are packed in shallow boxes with one, or at most two, layers of bunches packed in each box thus preventing the bruising of the flowers. The boxes often employed are 4 by 10 by 12 or 5 by 12 by 24 inches in depth, width, and length. The amount of wrapping on the boxes will depend on the temperature and other conditions at the time of shipment.

Exhibiting.

Exhibitors should keep the flowers off their vines until four or five days before the exhibition, and three days before this event a shade of cheese-cloth should be erected over the orange-, scarlet-, and blue-flowered varieties to prevent the scorching of the blooms. This shading must be removed after the exhibition flowers are cut. The spikes are cut so that all the flowers are fully open when they are judged. The ideal spike has a stem 12 to 18 inches long with four flowers. Twenty spikes loosely arranged so that each may be easily seen, is the proper number for a vase. The stems may be kept in the proper position by placing in the vases some 2-inch pieces of stiff reeds or grass stems. Some gypsophila may be used in the vases if permitted by the rules of the competition. Arrange the vases of a collection of varieties so that colors do not clash and so as best to exhibit the merit of the blooms. The educational value of the exhibit is enhanced if each vase is neatly labeled with the name of the variety.

Insects and other pests.

Snails sometimes destroy sweet pea seedlings in frames or greenhouses, but can be prevented by scattering lime under the pots. The red-spider is sometimes troublesome in the greenhouse and outdoors, and can be controlled by the usual methods. The green aphis or "green-fly" attacks sweet peas under glass, but is easily controlled by regular fumigations of tobacco preparations. In the garden a larger green aphis, the clover aphis, is not infrequently found, but spraying with tobacco extract, nicotine, or kerosene emulsion will usually destroy them. Plants that are frequently syringed with cold water are seldom infested with insects.

Fungous pests.

The most prevalent fungous pest affecting sweet peas under glass appears to be Thielavia basicola, or root-rot. Infected plants have little or no root-system, due to the fact that new roots are constantly destroyed. The leaflets often turn yellow with white edges, finally dying and falling to the ground. Sometimes one portion of the plant may be dry and dead while the remainder is green, although it does not grow or produce flowers. In fact, it is sometimes a mystery how a diseased plant can continue to live with its very limited root-system. There are some other root-rot organisms, but their action is similar and the method of control is the same for all—the removal of infected soil or sterilizing it.

The powdery mildew attacks greenhouse sweet peas at any stage of growth if the proper temperature is not maintained. The application of sulfur to the heating-pipes will check this disease. Care must be taken not to use the sulfur too strong or the flowers will be injured. Outdoor mildew usually does not appear until late in the season when the plants are failing.

Sweet peas grown in the open garden may be attacked by the root-rots above mentioned or by anthracnose and mosaic diseases, which may be serious. The former attacks the leaves, stems, flowers, and pods, but is most frequently found on the latter which are attacked at any stage of development. The affected parts wilt and die. The disease can be carried over winter upon the seeds. The prompt destruction of infected plants, as well as the burning of all old vines in the fall and the use of clean seed or treating the seed before sowing, will do much to lessen the danger from this disease. The mosaic disease, which may be allied to or identical with the trouble known as streak in England, is a rather baffling disease to the growers. It is distinguished by a yellow mottling of the leaves and stems of the plant. This is often accompanied by a curling of the leaves. The plants become stunted in growth and cease flowering if they have reached the flowering stage. It is a disputed point whether it is a bacterial disease or not, but it seems certain that the trouble is transmissible by the feeding of aphides. No remedy is known except the obvious one of keeping insects in check and destroying affected plants by fire.

The dropping of the young flower-buds either in the open or under glass is usually due to physiological conditions. Low temperature, lack or excess of plant-food, too much nitrogenous fertilizer, lack or excess of water are among the causes of this trouble.

Growing sweet pea seed in California.

Up to about the year 1885, most of the sweet pea seed was grown in England, France, and Germany, and imported to this country; at that time the first attempt was made to grow the seed in California. This resulted in almost immediate success, and in 1900 more than 600 acres were devoted to the growing of the crop. Most of the sweet peas grown at this time were of the Grandiflora type and yielded an average of 1,100 pounds to the acre, sometimes in a good year even as much as 2,200 pounds. With the introduction of the Countess Spencer type of sweet pea, about 1904, however, the waved forms supplanted the Grandiflora type, the larger part of the acreage being now devoted to the Spencer type. Approximately 2,500 acres are now planted to the sweet pea.

The original Countess Spencer sweet pea was of a shell-pink color, but it was not fixed and many color sports were produced. At present there are about 150 distinct varieties of the Spencer type under about 460 different names, resulting from different growers finding the same sports, or from varieties which were not improvements on existing varieties of the same colors. The yield of seed to the acre of the Spencer type is much less than from the Grandiflora type, only about 250 pounds to the acre being obtained. This difference in yield is due to the structure of the flowers: in the Grandiflora type the keel is closed, not allowing the pollen to escape so that each variety must pollinate itself, and the varieties can be grown close together and yet remain true to color and type; in the Spencer type, however, the keel is open, allowing the pollen to be blown out, and, as a consequence, about 75 per cent of the flowers do not set seed; also the plants must be set far apart in order to keep them true to color and type.

A cross was made between the Spencer sweet pea and the winter-flowering sweet pea, resulting in the winter orchid-flowering sweet pea. This is a shyer seeder than the Spencer, yielding only about seventy-five pounds to the acre. The flowers resemble the summer Spencer except that the growth is dwarf and the foliage more pointed. If sown in August under glass in the eastern states, they will bloom from November until late in spring. If sown outdoors, they will bloom three to four weeks earlier than the summer type, just before the extreme hot weather.

There are four types of sweet pea now grown in California: the summer Grandiflora, the winter Grandiflora, both of these being grown only on a small scale; the summer Spencer, and the winter orchid-flowering. In addition, the Cupid, which grows 5 to 6 inches high, is occasionally grown, only about 30 acres a season being devoted to it.

The raising of the sweet pea seed is usually on a large scale. Large tracts of land are plowed in autumn about 10 inches deep, either by horse-power or large tractors, before the beginning of the rainy season. The field is then carefully disced and pulverized and left to settle. If the rainy season begins as early as October, the fields should be harrowed again after the rain and the seeds planted. However, if the rains do not come until late, the seed must be sown in the dry soil, although they will not germinate so evenly. The most successful seeding is done between November and January. The seed is sown mostly by four- or two- row horse planters, being planted 30 inches apart and 3 inches apart in the rows, and 2 inches deep. Between each named variety, at least 10 feet must be left to prevent crossing.

After the seed is planted, the field must be kept in good condition by hoeing. After each rain the ground between the rows must be broken up. As soon as the plants are up, a horse cultivator may be used which breaks the crust 2 or 3 inches deep and 3 to 4 inches from the plants: but hand labor must be used to cultivate nearer the plants. This must be done after each heavy rain, sometimes five times being necessary. Irrigation is seldom practised, as 10 inches rainfall is sufficient for a good crop of sweet peas.

By the latter part of March and April the winter or early sweet pea will be in flower, and the summer or late sweet pea begins to bloom in May. Now must begin the process of thinning. No matter how carefully the seeds have been selected, there will be some "rogues" and these must all be removed. The best among these may be tagged and kept for stock seed to grow later on. All novelties and the stock seed for the next year are usually planted and taken care of by hand.

After the thinning has been done, the plants are left to themselves, no supports being given them, until the seed is ripe. These seeds are not evenly ripened and the cutting must be done when the larger part of the seed is ready to be harvested. The cutting is performed by a specially constructed ripper drawn by two horses and cutting two rows at once. As soon as cut, the plants are piled in small heaps and left for several days to dry. They are then put in large piles to cure which takes from three to four weeks. As soon as all the seed is perfectly cured and sufficiently dry, the thrashing begins. This is usually performed by gasoline power, and the clean seed is run directly from the thrasher into the sacks.
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==Cultivation==
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===Propagation===
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===Pests and diseases===
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==Species==
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==Gallery==
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<gallery>
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==References==
*[[Standard Cyclopedia of Horticulture]], by L. H. Bailey, MacMillan Co., 1963
<!--- xxxxx  *Flora: The Gardener's Bible, by Sean Hogan. Global Book Publishing, 2003. ISBN 0881925381  -->
<!--- xxxxx  *American Horticultural Society: A-Z Encyclopedia of Garden Plants, by Christopher Brickell, Judith D. Zuk. 1996. ISBN 0789419432  -->
<!--- xxxxx  *Sunset National Garden Book. Sunset Books, Inc., 1997. ISBN 0376038608  -->

==External links==
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[[Category:Categorize]]

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