The belladonna is cultivated world wide, but it was originally a native species of Europe, growing in the wild in parts of Europe, western Asia, and northern Africa. The species grows well in soils that have a chalky composition; it thrives in woods and on waste grounds. The leaves of the herb are collected in the summer months, while the roots are dug up in the fall.
The percentage of alkaloid contained in the various parts of the belladonna herb is the main factor considered when the plant is sold in the market, the various aerial parts and roots are sold by analysis, and the value depends on alkaloid content.
The amount of alkaloid present in any part of the plant shows a wide variation. For this reason, it is very important, to cultivate the crop only under such conditions of soil and temperature which are most likely to result in the accumulation of the highest percentage of various alkaloids.
Ideally, it would be best to find out the soil type that results in the maximum accumulation of alkaloids in the herb. However, with specimens of the plant taken from the wild, it has been difficult to trace all the conditions that determine the variations in alkaloid content - the saving grace is the discovery that a light, permeable and chalky soil is ideal for this crop as plants grown in such soils typically contain higher amounts of useful alkaloids.
Plants grown in such soils with the added advantage of a site on the south-west aspect of the slope of a hill have been show to gives particularly good results - plants grown in such conditions show a higher percentage of alkaloids.
The climatic range within which the plant grows best lies between 50 degrees and 55 degrees N. Lat. and the plant can grow best at an altitude range of 300 to 600 feet, though plant populations can be found at sea level where the soil is calcareous, particularly where drainage is good and the required amount of shade can be found in the area.
The suitability of the soil in which the plants are grown is of the greatest importance to determine their alkaloid content. While cultivated plant tend to contain far less alkaloids than plant grown in the wild, this may apply only to plants transported to a soils that are unsuited for good growth.
At the same time, the percentage of alkaloids in the plants have also been found to be increased through the use of artificial aids, including the judicious selection of manure, the cleansing and preparation of the soil, the destruction of weeds.
When these are conducted in accordance with the latest scientific practice, they have been shown to result in a great improvement of the plants in all respects; they increase the bulk of growing plants, increase the yield and hike the percentage weight of alkaloid contained in the plants.
Plants were studied for nine years in one test, notes as well as statistics on the plants were taken from one season to the next, these examinations extending over nine years showed that the atmospheric conditions around the plants had a marked influence on the absolute alkaloid content of the belladonna plants. Plants grown in sunny and dry seasons typically had the highest percentage of alkaloid yields compared to plants grown in other seasons.
The alkaloid content of individual plants did not show any marked variation at different stages of growth when plants were tested from June to September. However, the alkaloid content of individual plants begins to fade in the fall and there is rapid loss of alkaloids, therefore, the ideal time to gather leaves may be from the month of June in the summer until the falling of the leaves and shoots in late fall.
Seeds that are sown during the fall do not always germinate, which is why, seeds are best sown in boxes inside a cool house or on a frame, early in March.
Seeds must first be soaked with boiling water or baked for a short time in an oven, in order to destroy the embryo of a small parasitic snail that along with a variety of other plant slugs and insects, is likely to attack the seedlings at a later time - the seeds must only be planted after they are all treated in this way.
At the bottom of the seed boxes, some pieces of chalk or lime can be placed along with the drainage rubble to facilitate water flow. The germination period of the belladonna seeds is long and seeds are very slow in germinating, the average seed will take four to six weeks or even longer to put out growth.
A general rule concerning belladonna seeds is that only about seventy per cent of all seeds sown can be relied upon to germinate. As the seeds of the belladonna are so vulnerable to attack by insect pests, especially if they are sown in the open, any of the potential seed beds must first be prepared with the greatest of care.
To prepare the seed beds, the initial treatment is to burn some rubbish on the ground, in this treatment, the whole soil is dug up and fired all over, all kinds of burnt vegetable material and organic rubbish is worked into the soil. Once the soil has been treated in this way, it is stirred up thoroughly and left as such for a few days exposed to the air and sunlight.
Once this period of aeration is over, the ground is leveled and raked finely and finally given a thorough drenching with boiling water to kill any remaining parasitic spores or insects. After this, the soil is left to dry and once it becomes friable, some sharp grit sand is added on the surface, this is again raked and only then are the seeds sown in a thin layer on the surface of the soil.
The seeds require considerable moisture to undergo germination at a proper time. Once the plants sprout out, the growing seedlings will become ready for planting out in the month of May, a period when the fear of frost has disappeared. Seedlings at the time of transplantation should ideally be about one and a half inch high each.
These seedlings may be placed into the soil following the rain, or in case of dry weather, the ground should be well watered first. For several days, the seedlings must be covered in and shaded from direct sun light using inverted flower pots.
Late frost can easily injure the seedlings and the use of a light top dressing of farmyard manure or leaf mould will serve to preserve young shoots from physical injury during the onset of any sudden or dangerous change in temperature and other unpredictable atmospheric phenomenon. Belladonna plants grow best in shaded sites.
The many difficulties associated with the cultivation of belladonna in the United States have been overcome by interspersing these plants with rows of scarlet runners, the other plants shade the growing herb, and this allows the belladonna to grow rapidly. Following transplantation, the healthy young plants will soon re-established at a new site, however, they will require regular watering in case of dry weather.
The growing belladonna plants need to be cared for, and all plants must be checked for parasites, the entire area where the crop is growing must be free from weeds and it is suggested that harvesting be done by hand.
The lone stem on each plant will reach about one and a half to two and a half feet by the month of September. If the plants in a crop are healthy and strong, then the leaves may be gathered at this time. The term 'leaves' used here is inclusive of the broken off tips of each plant, however, the coarser stems can be left on the plant and any of discolored part of the plants must be rejected and thrown away.
Any single plant must not be plucked of all the leaves, and leaving a plant denuded of leaves will result in the death of the plant.
Each individual plant must be thinned to two and a half to three feet apart from any other neighboring plant as winter approaches, as overcrowding can be a problem in the second year. This is because, in the second year, each plant will typically bear one or two strong stems and may take up more space at the site.
Another method to propagate the belladonna is to use the green tips and cuttings from the side branches. These root well and quite easily in early summer. The buds with a piece attached root can be taken off bigger roots in April and these may be planted to get new plants. This method of propagation is a very successful way of rapid propagation to grow bigger and strong plants at any site.
The majority of plants are lost in years with wet winters. This is because, young seedling unless they are protected by fallen dead leaves die off easily during the winter. The loss of plants during the winter is less likely to occur if they plants are growing on lighter soils, however, plants are much more likely to suffer damage from drought in the summer months.
Belladonna is also vulnerable to some insect pests. The primary insect species that attacks the leaves of the belladonna is an insect often called the 'flea beetle,' young plants are vulnerable to this insect. Such insects can attack plants if they are growing at sites exposed to plenty of sunlight in open areas. Plants growing at such sites attract the worst attacks from the beetle.
Plants grown in their natural habitat along well drained slopes and partly shaded under trees are less vulnerable to attack from the beetle. The flea beetle is therefore much less likely to have the opportunity to attack plants which are grown on grounds covered with a thick mulch of leaves.
The damp leaves on the ground keep the caterpillars of the beetles away, these caterpillars feed on the ground and dislike moisture, the damp leaves discourage the caterpillars and this ensures that plants are free of the beetle. Plants can generally be kept free of the beetle if a little naphthalene is scattered on the soil in which the plants are grown, the vapor from the compound will probably help repel the beetles.
Beetles can be caught in only one way; by spreading greased sheets of paper on the ground around the plants. Once the greased paper has been placed, slightly shaking each plant will disturbed a number of beetles and the insects will jump off like fleas and become trapped on the papers.
In the autumn months of the fourth year, all the plants are dug or ploughed up and all the roots are collected, carefully washed and then dried for processing and storage. Once the plants have been uprooted, the crop must be replaced by planting young seedlings or offsets of the old roots. If an incidence of wireworm is observed, the entire plant must be dug up and a seedling can be planted on the spot as a replacement.