|Rheum rhabarbarum subsp. var.||Rhubarb|
Rhubarb is a group of plants that belong to the genus Rheum in the family Polygonaceae. They are herbaceous perennial plants growing from short, thick rhizomes. They have large leaves that are somewhat triangular shaped with long fleshy petioles. They have small flowers grouped in large compound leafy greenish-white to rose-red inflorescence. While the leaves are toxic, the plants have medicinal uses, but most commonly the plant's stalks are cooked and used in pies and other foods for their tart flavour. A number of varieties have been domesticated for human consumption, most of which are recognised as Rheum x hybridum by the Royal Horticultural Society.
|Standard Cyclopedia of Horticulture|
Rhubarb. A garden vegetable, perennial, grown for the thick acid leaf-stalks which are used in spring for sauces and pies.
Rhubarb, known also as pie-plant, is a hardy plant and will withstand considerable neglect, yet, like most cultivated vegetables, it responds readily to proper care and good treatment. The large fleshy leaf-stems desired in culinary use are produced in part by the great store of plant-food held in reserve by the many big roots. Everything should be done to increase this supply of reserve food. Tillage and fertilizing, therefore, are fundamentals. In the choosing of a site a southern exposure is preferred, with sufficient slope to give good drainage. Plow the ground 6 to 8 inches deep, draw furrows 5 feet apart, set the plants 3 feet apart, with the buds 1 inch below the level of the ground. In home grounds, spade or trench the land deep, and set about 4 feet apart each way; or if in only one row or line with plenty of room on either side, the plants may go 3 feet or even as close as 2 1/2 feet if they are well manured and often renewed. If the soil lacks in fertility, mix compost with the earth that is placed about the roots; never put fresh manure next to the roots. As soon after planting as possible, start the cultivator, and give a thorough stirring at intervals of six to eight days up to the middle or last of August. After the ground is frozen, cover the rows 3 to 4 inches deep with manure that is as free as possible from weed and grass seed. As early in the spring as the ground can be worked to advantage, start the cultivator and work the manure into the soil. Each alternate season the surface of the soil should have a good dressing of manure. For garden culture, a similar practice should be undertaken with the hoe or other hand tools.
In field culture, the third or fourth year after planting the hills should be divided. Remove the earth from one side of the hill and with a sharp spade cut through the crown, leaving three or four buds in the hill undisturbed. This work should be done in the fall or early in the spring. In garden culture, the teds should be similarly renewed, at least as often as every four or five years, but more pains may be taken in dividing the plants. The clumps of roots grow so large, and have so many eyes, that the stalks soon become more numerous than desirable, and run down in size. Take up the entire roots and cut them in pieces, leaving only one strong eye to the piece, and plant the pieces in a newly prepared bed (or even in the old one if properly enriched and prepared)4 feet apart each way as before.
Seed-stems are produced freely the entire season These should be promptly pulled up, unless seed is wanted. The growth of these stems and the production of seed tend to lessen the vitality of the plant and to reduce the yield. Propagation of rhubarb is commonly by division the roots, and this is the only method by which a par-ticular type can be increased. Propagation from seed, however, sometimes proves satisfactory, and always interesting as the seedlings vary greatly. The seed germinates easily, and if started early the plant become fairly large and strong the same season. The may be started in any good clean garden soil. Sow seed in early spring, in rows a foot apart and not over an inch deep. Thin the plants promptly to stand a few inches apart in the rows, and give the same thorough tillage allowed to other garden crops. In the following fall or spring take the seedlings up, and set them in the well-prepared per-manent patch, not less than 4 feet apart each way, and till frequently the entire season. In spring of the next year the stalks may be pulled freely.
From ten to twenty good plants should supply the needs of the usual family, and probably with something to spare for the neighbors. Sometimes an early supply is secured by placing a bottomless barrel or box over the plant and piling warm horse-manure about it. If the barrel, keg, or box is not too broad, the petioles will make a straight upright growth and will be partially blanched and very tender. Victoria and Linnaeus are the leading varieties. L. H. B.
Forcing of rhubarb.
In the winter and early spring months, the forcing of rhubarb in the vicinity of many city markets is a profitable industry. The plant may be forced either in the field where the roots were grown or lifted and placed in hotbeds, under greenhouse benches or in cellars. The bulk of the rhubarb forced for market and sold during the winter months is grown in cheap structures placed over the plants in the field. These houses may be of the lean-to type, although they are more commonly even-span post and rafter construction, the roof being covered with hotbed sash which is not needed for other purposes at the time. The side walls are 4 to 5 feet high, made of rough boards and covered with cheap building-paper. The even-span houses are mostly 24 to 36 feet wide and the lean-to house half that width. Heat is usually applied in an overhead system, steam being the most popular, although late in the season the sun is depended upon to supply the required amount of heat. When forced in the field in limited quantities, coldframes are often used, the outside walls being well banked with hot manure and the surface of the ground within the frames covered with 3 to 6 inches of the same material.
Beds intended for early spring forcing should be thoroughly cultivated in the fall and an application made of high-grade commercial fertilizer of 800 to 1,000 pounds to the acre. When growth starts, a dressing of nitrate of soda at the rate of one-half pound to a crown should be given. In field forcing, the moisture of the soil is usually sufficient so that no water is applied. When it is the intention to use a field for forcing for several years, the plants are usually set 2 by 3 feet and the land fertilized heavily each spring with a compost, one made from cow- and hog-manure being preferred. The sash are placed upon the first houses as soon as the roots have been frozen, five to seven weeks being necessary to bring the plants to maturity.
In field forcing, the cost of production is often greatly reduced by growing spinach or dandelion between the rows, the price obtained for these fillers usually being sufficient to pay labor and maintenance costs. The stalks are usually pulled twice, returning to the grower from $1 to $2 a sash, depending upon the season when placed upon the market.
Roots for forcing in the dark should be healthy and vigorous; the larger the roots the more satisfactory the results as a general rule. Crowns three to five years of age are mostly used, although satisfactory results are often obtained from one-year-old plants which have been grown on very rich land and have made an unchecked growth during the season. The roots should be dug early in the fall before the ground freezes and allowed to remain exposed to the weather until they are frozen solid when they should either be removed to a shed or covered with litter in the field to prevent alternate freezing and thawing. Thorough freezing is necessary, whatever the method of forcing, if the best resulte are to be obtained. With one-year roots very satisfactory results are sometimes secured if the roots are thoroughly dried before forcing. Anesthetics have been tried as a substitute for freezing but with unsatisfactory results. When used upon frozen roots they stimulate growth, resulting in the production of earlier and larger stalks with greater total weight of product. If the greatest benefit is to be derived from the anesthetic, it must be used in the early part of the resting-period. The most satisfactory results have been obtained by the use of 10 cubic centimeters of sulfuric ether to a cubic foot of space, exposing the roots to the fumes for forty-eight hours. Well-grown two-year-old roots seem to respond to this treatment in the most satisfactory way.
As soon as the roots are placed in position, whether it be under the greenhouse benches or in the cellar, all spaces should be filled with soil or ashes to prevent evaporation. If placed on a concrete floor, 2 or 3 inches of soil should be placed under the roots and sufficient material should be added completely to cover the roots. The bed as soon as completed should be thoroughly watered, the plants kept supplied with an abundance of moisture, which will necessitate water being applied about once a week. Care should be taken to guard against over-watering as this will result in the production of light-colored stalks, lacking in flavor and texture. In order to obtain the most attractive product, rhubarb should not be forced in full light or total darkness. If grown in diffused light, the development of the leaf-blade is very slight and the color of the stalk, instead of being green, is a beautiful dark cherry-red, giving to the product a very attractive appearance. In quality the product is superior to that forced in light, being more tender, less acid, with a skin so thin and tender as to make it unnecessary to peel the stalks. The temperature may range from 45° to 75°, the lower the temperature the greater the yield and higher the quality of the product. The time required for bringing a crop to maturity in darkness is practically the same as that required for forcing in the field.
Local market demands to a certain extent govern the method which is used in growing this crop for the winter market. When grown by any method which requires the lifting of the roots, it must be remembered that they are worthless after having produced a crop. Therefore, this method cannot be practised with as great profit upon expensive land as can the method of field forcing or when roots were used for forcing which otherwise would be destroyed. Rhubarb-forcing in house cellars should receive more attention, as it adds at slight expense a pleasing vegetable to the winter dietary.
Whatever the method practised, success will be attained only when healthy well-developed roots, which have been allowed to freeze, are used.
Rhubarb is now grown in many areas and thanks to greenhouse production is available throughout much of the year. Rhubarb grown in hothouses (heated greenhouses) is called hothouse rhubarb. This rhubarb is typically made available at consumer markets in February and March, before outdoor cultivated rhubarb is available. The hothouse rhubarb is usually a brighter red than the cultivated rhubarb. Hothouse rhubarb is also more tender and tastes sweeter than cultivated rhubarb. In temperate climates rhubarb is one of the first food plants to be ready for harvest, usually in mid to late spring (April/May in the Northern Hemisphere, October/November in the Southern Hemisphere), and the season for field-grown plants lasts until September. In the northwestern US states of Oregon and Washington, there are typically two harvests: one from late April to May and another from late June and into July. Rhubarb is ready to be consumed as soon as it is harvested, and freshly cut stalks will be firm and glossy.
In warm climates, rhubarb will grow all year round, but in colder climates the parts of the plant above the ground disappear completely during winter, and begin to grow again from the root in early spring. It can be forced, that is, encouraged to grow early, by raising the local temperature. This is commonly done by placing an upturned bucket over the shoots as they come up. Because rhubarb is a seasonal plant, obtaining fresh rhubarb out of season is difficult in colder climates, such as in the UK.
Rhubarb can successfully be planted in containers, so long as the container is large enough to accommodate a season's growth.
The colour of the rhubarb stalks can vary from the commonly associated crimson red, through speckled light pink, to simply light green. Rhubarb stalks are poetically described as crimson stalks. The colour results from the presence of anthocyanins, and varies according to both rhubarb variety and production technique. The colour is not related to its suitability for cooking: The green-stalked rhubarb is more robust and has a higher yield, but the red-coloured stalks are much more popular with consumers.
Pests and diseases
- Standard Cyclopedia of Horticulture, by L. H. Bailey, MacMillan Co., 1963
- w:Rhubarb. Some of the material on this page may be from Wikipedia, under the Creative Commons license.
- Rhubarb QR Code (Size 50, 100, 200, 500)
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