Cultivation plots

© DHU

Seeds are sown in Terra Medica in February/March once the greenhouses have been sufficiently heated by the spring sunshine and they offer favourable light conditions. The majority of plants can be grown in such an environment.

Sowing with care

© DHU

Some plant species, such as the foxglove (Digitalis), daisy (Bellis perennis) and dandelion (Taraxacum), are sown in June/July for harvesting the subsequent spring. We mainly use our own seeds for the purposes of cultivation. Propagation is achieved by dividing or taking cuttings, since for reasons of quality the wild type should wherever possible be cultivated. Neither elite seed nor varieties are used.

Harvesting after 10 am in the sunshine

© DHU

 When harvesting, as little water as possible should be left on the plants. The morning dew (by harvesting after 10 am) and rainwater need to be avoided, therefore. As defined by the manufacturing specifications of the German Homeopathic Pharmacopoeia (HAB), the plants must be dry. This also offers the advantage that hardly any soil adheres to the plants when they are dry. A further method for minimising the percentage of water – such as in the case of the marigold (Calendula) – is to not water the plants for one or more days prior to harvesting so that they are not sapping too much when harvested.

 Plants with delicate foliage, such as Eschscholzia californica (California poppy), must be handled very carefully during the harvest. In summer, they can perish within an hour. The harvesting time depends, amongst others, on the vegetation phase and the weather conditions. Parts of the plant such as the bark can also be harvested all year round. No attention is paid to the lunar calendar at DHU. Either the whole plant or parts thereof are used in accordance with HAB. The roots are washed with as little water as possible. The parts above ground are cut off with pruning shears, sickle or hedge trimmer; lavender and chamomile blooms are collected with combs, and bark is peeled off.

Should a crop fail, plants are sourced from certified farmers or our requirements are met by using approved, sustainable wild stocks. We also have a limited excess stock of mother tinctures to hand. As a rule, therefore, we can survive a less fruitful harvest without difficulty.

Outside sources always approved

 Some of the starting materials required by DHU each year are obtained from wild foraging. Professional foragers are appointed to gather such stocks. The company is familiar with the areas foraged, though they can vary depending on the vegetation period. For example, if the flowers of a spring bloomer are required in the summer, foragers inevitably have to venture into regions of higher altitude. Attention is of course paid to protecting species, meaning that all sources must be approved in advance by the competent nature conservation agencies. To this end, DHU works closely with the German Federal Agency for Nature Conservation.

To ensure that the range of remedies required for the homeopathic therapy is assured, sustainable sources of wild plants are also essential in the future. As a rule, only small quantities are involved.

Crop rotation through diversity

© DHU

Having been cultivated in the greenhouses, the medicinal plants are transferred to open farmland. Attention is thereby paid to crop rotation – due to the numerous species of plants being cultivated, they are automatically relocated. This is important, since most plant species do not readily tolerate several periods spent in succession in the same place. The balloon plant (Cardiospermum), for instance, is not compatible with its own kind, since it probably secretes an inhibitor via its roots. Other plants such as chamomile (Chamomilla) or marigold (Calendula) are not problematic and may be cultivated for years at a time in the same location.

Cultivation does not always work

Not all medicinal plants can be cultivated on Terra Medica. This applies above all to species which are particularly demanding when it comes to their environment (soil, location, climate).

Examples are bog plants such as Kalmia (mountain laurel) or Ledum (wild rosemary), which require a very acidic environment. Even a simulation of the conditions they require does not necessarily mean that they will be successfully cultivated, since one species may often depend on a functioning biological environment in order to thrive. Euphrasia officinalis (eyebright), for example, only grows as a hemiparasite amongst a community of meadow plants.

Not even the common arnica (Arnica montana) feels at home in the Rhine Valley. The epithet “montana” here, derived from “mons” for mountain, signifies the area in which the plant prefers to live.

Trial cultivation is a major challenge

© DHU

For a variety of reasons, it may be necessary to cultivate plants that have not yet been grown before. Provisions for the conservation of species are strictly heeded. Unfavourable weather conditions, such as long dry periods in the areas that are foraged, can lead to shortages in supply. Often, high-quality raw materials can therefore only be guaranteed in the long term by means of specific cultivation.

Trial cultivation is therefore one of the activities also pursued by our experts in Terra Medica. The trials reveal the conditions the plants require, how to achieve vegetative (production of new plants from parts of plants) or generative (sexual reproduction from seeds) propagation, and the yield that can be expected. Usually, methods of cultivation are only tested on a few species, since such development activities are very labour-intensive and can take several years. We also have excellent partnerships with global experts.

To date, roughly 40 plant species have been obtained through trial cultivation, such as Pelargonium reniforme and Pelargonium sodioides (geranium), Caulophyllum (blue cohosh), Podophyllum (May apple), Paeonia (peony) and Adonis (Adonis rose). In the case of Pseudognaphalium obtusifolium (rabbit tobacco), it took 10 years to find the correct starting material.