Rhubarb (Rheum rhabarbarum)
In Central Europe, apart from rhubarb, two other species of the knotweed family are grown (Polygonaceae), namely buckwheat and sorrel. Many other plants belong to this family, especially weeds, from field knotweed to tall vines, like Aubert's knotweed. Most of the plants in this family are vigorous growth and like slightly acidic soil. A characteristic feature of almost all knotweed plants is the red color of the petioles, especially pronounced in rhubarb. Even today, the quality of this vegetable is judged on the basis of the intensity of the color of the petioles.
The homeland of rhubarb is Tibet and West China. It was cultivated there for many centuries before our era. It came to Europe in the Middle Ages as a medicinal plant, and later found use as a vegetable. Only in the middle of the last century did it reach the northern part of Germany via England. Simultaneously with the cultivation, new varieties were also cultivated, the aim of which was to obtain plants with long and thick petioles and as intense as possible, red tint. In Poland, the varieties of 'Wiśniowy' are recommended, 'Early Hosera', 'Leader of Europe'. Rhubarb is a large perennial that forms an underground carp with roots and buds, from which large leaves grow on thick petioles. Like other plants, who like a lot of fresh caries (pumpkin, cucumber), rhubarb also covers the soil surface with large leaves, creating a perfect microclimate. This favors the growth of long and delicate leaf petioles. As with cucumbers, rapid leaf development in spring is very important. So abundant organic fertilization is necessary, e.g.. well-decomposed manure. In late autumn, one plant should be given 3-5 blades of such fertilizer. Part of the fertilizer is left on the surface of the soil, and a part is mixed with its top layer. Before establishing a new plantation, fertilization must be even more abundant, and the soil is loosened at a depth of 40-50 cm.
The new plantation is established from plants derived from the division of the old carp. It is cut into 2 or 4 parts with a sharp knife; the cut surface should be even and smooth. Otherwise the carp will rot quickly. Generative reproduction (from seeds) it is not advisable. The carp should not be divided either, which were previously driven in winter. Divided carps can be soaked in Preicobact or Oscorna-Wurzelstarkung before planting.. Rhubarb is best planted in the fall. Rhubarb breeds only exceptionally in March. The stumps are planted deeper, than they grew earlier, so that the top of the bud is a few centimeters below the soil surface. One plant needs approx 1,2 m2 of space. 2-3 plants are enough for personal needs.
In the first year after planting, the plants develop slowly and do not yield high yields, however, they require very careful care. Only in the second year you can expect a larger collection of petioles. Harvesting starts in April, and when applying soil mulching, e.g.. with straw or decomposed horse manure, much earlier. Do not cut all the leaves at the same time, because some of them are needed for the further development of the plant. Growing inflorescences must be removed as quickly as possible, because they weaken the mother plant. Depending on the weather, harvesting of leaves should end around mid-June. Extending the harvest will greatly weaken the plant, and the quality of the tails is also much worse. Rhubarb can be grown in one place for 8-12 years, then dig up the stumps, divide and plant in a new place. Too sour taste of rhubarb can be mitigated by the use of biodynamic preparations, especially silica. Rhubarb, a vegetable very easy to grow, it should grow in any garden.