The good quality of medicinal plant materials mainly depends on compliance with the terms of harvesting, optimal collection technique and drying conditions.
Medicinal plants are harvested during the growing season, when they accumulate the maximum amount of active principles. It is experimentally proven that in the aboveground parts of the plant the content of biologically active substances reaches a maximum during flowering and at the beginning of fruiting, in fruits – during full ripening, roots – after the death of the aboveground part, bark – in the period of spring sap movement.
Aboveground parts of the plant should be collected only in dry weather, in the middle of the day, when the plants dry out from the dew. Underground parts can be dug in wet weather: they still have to be washed before drying. Dusty or contaminated herbs, grown near highways and railways, as well as those damaged by insects, rust or fungal diseases should no not be harvested.
Collected leaves, flowers, berries, etc. are recommended to be placed in baskets as loosely as possible; bark and roots are stacked in bags, but not tightly, to avoid self-heating of the moist mass. Raw materials should not be left overnight in the container in which it was brought – this leads to the destruction of the active substances. If the drying is delayed, for some reason, the raw material should be spread in a thin layer on the boards, in a room protected from rain and dew. In this form it can be stored no more than 10-12 hours.
For medical purposes, bark is harvested only from young branches; the bark of old branches and trunks, covered with a thick cork layer of dead tissue, is not harvested. It is desirable to harvest bark and buds from felled, cut or sawn branches in forest stands, and not from trees and shrubs that are still growing.
BUDS are harvested during early spring, when they are swollen but not yet burst. They can be collected in different ways: pine buds cut with 2 – 3 mm shoots of the previous year; birch buds are usually collected during the harvesting of brooms, peeling branches. Before drying, impurities and buds that have begun to bloom should be removed.
BARK is harvested from young branches in the spring, in April-May, during the period of active spring juice movement, when it is easily separated. It is necessary to have a knife with a very sharp end, by which one should make several transverse incisions at a distance of 20-30 cm and 2-3 longitudinal ones, after which the bark can be pulled in the direction of the lower incision, without reaching its level and left for a while to dry, then stripped. No wood should remain on the peeled bark. Bark should not be collected from branches affected by lichens or other growths.
LEAVES are carefully plucked by hands before the beginning or during flowering of the plant until the flowers wither, at the beginning of fruiting, without disturbing the growth of the plant. While harvesting leaves from wild perennials, some of them should be left so that the plant will not die. The leaves should be clean, undamaged, green. Sometimes they are removed from a pre-dried plant.
FLOWERS are collected during the flowering period, but more often at the beginning of it, preventing the disintegration of the flower or inflorescence. In most plants, the flowers are cut off by hand; sometimes whole inflorescences are collected, after drying they are rubbed through a sieve, freed from peduncles (e.g., in elderberries).
FRUITS, SEEDS are harvested ripe. Juicy fruits are harvested by hands, without stalks, early in the morning or evening. It is better to collect fruits in baskets lined with burlap inside, because the fruits that are collected in a bowl spoil quickly. Between the layers one can put twigs with leaves. The seeds, cleaned from dust and impurities, then are air-dried slightly. Sea buckthorn berries or juniper cones are harvested by shaking the branches. Rose hips are plucked together with the remnants of sepals, which are easily separated after drying. Spoiled and damaged fruits should not be collected.
UNDERGROUND ORGANS can be dug in the spring, but its better to dig them in the autumn (in the southern areas a little earlier), when the aboveground parts begin to wither, but one can still recognize the species. The advantage of autumn harvesting is that the underground organs are larger, due to the accumulation of starch and other valuable substances in them during the summer. In addition, during the autumn harvest, fallen seeds allow natural regeneration of thickets. The plant is dug up within a radius of 10-15 cm from the stem, deepening the shovel into the ground so as not to prune the roots and rhizomes; then they should be overturn together with the soil, thoroughly cleaned of soil residues and washed in running water. The roots are washed the best in baskets, boxes. Thick roots are cut into several parts.