Harvest bark on a day that is dry enough for there to be no surface water present on the branches. Usually it’s best to prune what is needed from the tree or shrub, (taking care not to butcher it!) and complete the preparation in a convenient work area. The reason for this approach (apart from convenience!) is that removing the bark from a living branch will kill it anyway. Certainly no bark should ever be removed from the trunk or main boughs of mature trees. Having gathered the prunings, remove any twigs and immature (green) growth, then cut the branches into a series of straight sticks of manageable length to facilitate stripping.

Some barks need to be dried before further preparation, especially those containing anthraquinone laxatives such as Cascara and Alder Buckthorn, which should be dried and then stored for at least two years to avoid an excessively cathartic action. As this is a list of tinctures made from fresh herbs, these will not be covered here, although the principles are the same.

Barberry bark, Berberis vulgaris1:2 30%, 2 -3 weeks

The native Barberry can be harvested either in late autumn or early spring. Beware of the vicious spines when handling – these and any leaf stems can usually be knocked off with the back of a knife during preparation. Cut close to the base, and discard top growth where it becomes thinner than 1cm. Strip by whittling and scraping with a small kitchen- or pen-knife. Also note that the yellow berberine will stain the hands (and anything else) and is very hard to remove. The best quality is derived from the root bark. Dig up the whole plant and trim off the roots to derive sections not less than 0.5cm thick. Clean off the soil, allow any surface water to dry, then whittle and scrape off the root bark. This can be incorporated with the stem bark if you wish. Leave at least a third of the roots intact if you’re going to replant the shrub.

The evergreen American Oregon Grape, B. aquifolium (syn. Mahonia aquifolium) grows well in the UK, and can be prepared in all respects the same as Barberry.

Cherry bark, Prunus serontina, P. avium. – 1:2 30%, 14 days

Cherry bark can be harvested at any time, but ideally in the autumn after leaf drop, or just before budding in early spring. Prune off small branches, (1cm – 4cm), aiming to thin the upper growth without spoiling the shape of the tree. Larger branches should have a proprietary sealant applied to the cut end to avoid diseasing the tree. Discard twiggy growth. Stripping Cherry Bark is achieved by a painstaking mixture of whittling and scraping with a hand-knife. Be sure to get all the inner bark which is the most potent part.

Textbooks always recommend the Wild Cherry, Prunus serontina, a native of America but easily grown in the UK. However, experiments with modern cultivars of P. avium, the Sweet Cherry, show that a very good result can be derived from prunings of these fruiting garden subjects, having enjoyed the cherries earlier in the year. Whether other species or ornamental Flowering Cherries are viable is open to experimentation.

Cramp Bark, Viburnum opulus1:3 25%, 14 days

Cramp Bark, the Guelder Rose, needs to be taken in late autumn between leaf drop and bud formation. The dead leaves are tenacious so you may need to pick them off once there is minimal resistance. Don’t delay as new leaf buds form immediately after and will obstruct stripping of the bark. The ideal is to coppice the shrub (i.e. prune drastically, leaving only the stubs of main stems) so that it branches in straight wands in subsequent years – these are much easier to strip than the shrub’s natural habit (tangled and many-branched). The classic stripping technique is with a small kitchen knife held more or less at right-angles to the branch, driving thin curls of the bark before it, working methodically round the branch and from top to bottom. If supplies are short, small twigs can be chopped up and incorporated with some benefit.

Contrary to some texts Viburnum opulus is native throughout the UK. It should not be confused with the Wayfarer’s Tree (V. lantana) or the many aromatic Viburnums popular with gardeners, none of which share Cramp Bark’s medicinal virtues. The American Black Haw, (V. prunifolium), is medicinal but has not been grown successfully in the UK.

Oak bark, Quercus robur1:2 25% 4 – 6 weeks

Bark from the mighty English Oak is taken in early spring from young trees on which new growth is relatively accessible – ripened, but still with smooth moss-free bark, 1cm – 8 cms diameter. Oak bark can be whittled off, although some authorities suggest that it can be split and peeled.

Medicines have been prepared from the leaves and also the fruits (acorns) in the past. In particular collect Oak galls (or “Oak Apples”) if you come across them in early spring as leaf buds are forming – these can be tinctured (same formulation as for bark), or are often powdered, producing what is said to be the most powerful astringent of all.

Willow Bark, Salix spp. – 1:3 25%, 2 – 3 weeks

Willow bark can be harvested at any time during dormancy but achieves optimal quality in the spring just as the first leaf buds start to form. The “wands” of the previous year’s growth are pruned off, discarding under-ripe or twiggy growth from the extremities. It should be easy to strip the bark off with the flat of a small hand-knife in the same fashion as Cramp Bark. Young willows are particularly happy to be “coppiced” (recurrently cut back hard to near ground level) resulting in vigorous production of easy-to-harvest wands.

The American Salix nigra has pride of place in existing texts, the European S. alba being accorded different (and lesser) properties. However, as often happens, these differences appear minimal when using fresh material. There are also many species and hybrids developed for use as windbreaks, biomass and for basket-weaving, as examples. These are all potentially therapeutically viable – certainly a modern hybrid (unidentified) used by one UK grower-producer, primarily as a windbreak, has yielded consistently outstanding medicinal results.