These are the general features of a ground which is recommended for the culture of medicinal plants or herbs. A plot of ground, whose surface is not broken or rendered uneven by the presence of holes, ditches, gravel and stones, nor is loose in its character, and which is not disfigured by ant-hills, nor used for the purposes of a cremation or execution ground, and which does not occupy the site of a holy temple, is favourable for the growth of medicinal herbs. A ground which possesses a soil which is glossy, firm, steady, black, yellowish or red and does not contain any sand, potash or any other alkaline substance, and is favourable to the germination of plants and easily pervious to the roots of plants growing thereon, and which is supplied with the necessary moisture from a close or adjacent stream or reservoir of water, is recommended for the growth of medicinal plants and herbs. Plants should be regarded as partaking of the virtues of the ground they grow upon. A plant, growing in such a commendable site, should be examined as to its being infested with worms or insects, or as to its being anywise infected with poison, or cut with an arm, or affected by winds, atmospheric heat, or an animal's body. It should be culled or uprooted in the event of it being found sound, healthy, deep-rooted, full-bodied, and of matured sap. The gatherer should look towards the north at the time of culling.
A plot of ground with a pebbly, steady, heavy, dusky or dark coloured soil, and which conduces to the growth of large trees, and yields rich harvests of corn, should be regarded as permeated with the specific virtues of essential Earth-matter.
A ground having a cool, glossy, white coloured soil, which is adjacent to water, and whose surface is covered with a lavish growth of glossy weeds and luscious shady trees, should be considered as characterised by the essential properties of water (Amvuguna. A ground having a gravelly soil of varied colours, and which contributes only to the germination of scanty and yellowish sprouts, should be looked upon as permeated with the attributes of essential fire (Agniguna). A ground with an ash-coloured or ass-coloured (grey, soil, and on which withered looking, sapless, large-holed trees of stunted growth, somehow eke out a miserable existence, should be considered as being controlled by the specific properties of air (Anilaguna); while the one having a soft, level surface with large trees and lofty hills cropping up at intervals thereon, and which is covered with growths of weeds and under-shrubs, and is endued with a dark soil, kept moist and sappy by the percolation of invisible (subterranean) water, should be looked upon as permeated with the essential properties of sky (Akashaguna).
According to certain authorities, the roots, leaves, bark, milky' exudations, essence and fruits (seeds) of medicinal plants and herbs, should be respectively culled in the early part of the rains (Pravrit) and in the rainy season proper (Varsha), autumn, (Sharat), fore-winter (Hemanta), spring (Vasanta) and summer (Grishma). But we cannot subscribe to that opinion inasmuch as the nature or essential temperament of the earth is both cool (Saumya) and hot (Agneya). Accordingly drugs of cooling virtues should be culled during the cold seasons of the year, and the heat-making ones in the hot season, as they do not become divested of their native virtues at those seasons of the year. Medicinal plants of cooling virtues, which are grown on a soil of cool temperament and are culled during the cool seasons of the year, become intensely sweet, cooling and glossy. These remarks hold good of other medicinal plants and herbs.
Herbs of purgative properties, which are grown on a soil permeated with the specific virtues of water or earth matter, should be culled as the most effective of their kind. Similarly, herbs of emetic virtues should be culled from a ground permeated with the essential virtues of fire, sky and air.
Herbs exercising- both purgative and emetic virtues should be culled from ground exhibiting features common to both the two aforesaid classes of soil. Similarly, herbs possessed of soothing properties (Sanshamanam) * are found to exert a stronger action in the event of their being reared on a soil permeated with the essential properties of sky.
All medicinal herbs and substances should be used as fresh as possible, excepting Pippali, Vidanga, Madhu, Guda, and Ghritam, (which should be used in a matured condition i.e. not before a year;. The milky juice or sap of a medicinal tree or plant should be regarded as strong and active under all circumstances. Herbs and drugs, that had been culled or collected within the year, might be taken and used in making up a medicinal recipe in a case where fresh ones would not be available.
Authoritative Verses on the Subject - Medicinal herbs and plants should be recognised and identified with the help of cowherds, hermits, huntsmen, forest-dwellers, and those who cull the fruits and edible roots of the forest. No definite time can be laid down for the culling of the leaves and roots of medicinal plants, etc., such as are used in compounding the recipe, which is called the Patra-lavanam, and which covers, within its therapeutic range, diseases, which are peculiar to the entire organism (such as Vata-vyadhi, etc). *
* Herbs or drugs, which in virtue of their own essential properties soothe or subdue a disease without eliminating the morbid humours or without exercising any emetic or purgative action.
As soil admits of being divided into six different classes according to its smell, colour, taste, etc. so the sap of a medicinal plant may assume any of the six different tastes through its contact with the peculiar properties of the soil it grows on. Tastes such as, sweet, etc., remain latent in water, which imparts them to the soil in a patent or perceptible condition.
A plot of ground, exhibiting traits peculiar to all the five fundamental material principles (such as the earth water, fire, etc.), is said to be possessed of a soil of general character (Sadharani Bhumi), and medicinal plants and herbs partake of the specific virtues of the soil they grown on.
Drugs, whether fresh or old, and emitting a contrary smell, or in any way affected as regards their natural sap or juice, should not be used for pharmaceutical purposes.
The virtues of such medicinal drugs and substances such as Vidanga, Pippali, Madhu, and Guda, improve
* Hence the doctrine, as regards the culling of the different parts of a medicinal plant such as, the leaves, roots, etc., in the different seasons of the year, naturally falls to the ground.
(after a year). Accordingly all drugs and medicinal herbs, excepting the preceding ones, should be used fresh and unsoiled, or uninjured by insects.
Blood, nails, or hair etc., of animals, (officinally laid down to be used in our Pharmacopoeia), should be taken from young and healthy animals, and the ordure, urine, or milk of an animal, (enjoined to be used for medicinal purposes), should be collected at a time after it has completed its digestion.
The pharmacy and the medicinal store of a physician should occupy a commendable site and an auspicious quarter of the sky (North or East), and the collected medicines should be kept tied in pieces of clean linen, or stored in earthen vessels and hollow tubes of wood, or suspended on wooden pegs.