Stratification — the method of pretreatment of seeds consisting in imitation of winter conditions in which the seed stays in the nature before germination. Seeds of many plant species have to pass through stage of rest of germ. Otherwise they will not sprout at all. Stratification is applied most often to seeds of garden cultures.
For what stratification is necessary?
Stratification — the word of Latin origin. In literal translation means "stratification". Before at us this method called "peskovaniye". Seeds of stone and seeded cultures poured sand and several months maintained at small positive temperatures. Similar reception considerably increased viability of seeds.
For what did it become? In the winter in the nature the seeds of many trees and bushes fall down on the earth in the fall when conditions for germination still remain. If seeds had no dormant period, shoots would ruin autumn frosts.
Seeds of other trees and bushes, on the contrary, long hang on branches. They fall down late in the fall or in the winter. Protected by firm cover, seeds well remain till spring under snow. To this period in seeds there are important physiological processes. At suitable temperatures and enough air the seeds are prepared for germination. Their cover is softened, complex organic matter turns into simple, easily available to assimilation by germ. The stratification method for seeds with hard viability artificially creates the conditions similar by it in which they exist in the habitat.
Ways of stratification of seeds
Now apply two types of stratification: warm and cold. At warm stratification the wetted seeds place in conditions with the increased humidity, sufficient air flow and temperature 10-35os. Warm stratification is usually necessary to seeds with underdeveloped germ, for example, to magnolia vine seeds. For seeds of separate plants it is recommended to carry out stratification in two stages. That is at first in the warm way, then cold. At cold way of stratification for the majority of cultures temperature from zero to plus five degrees is optimum. Seeds within several days ret in water. Water is periodically changed at the same time. It is also recommended to disinfect seeds potassium permanganate solution. Then seeds pour sand and other substrate (peat, peat dust). Container with mix of seeds and substrate is placed in the fridge or the basement. At seeds of different cultures the terms of stratification are various. Its duration can be from two-three weeks to seven-eight months. Therefore before stratification of seeds of specific cultures it is necessary to study previously the recommendations of specialists in its duration and conditions.