Common buckthorn, Rhamnus cathartica, is also known as purging buckthorn and European buckthorn, or just buckthorn. It is a shrub or small tree which reaches a height of up to 6-10m (18-30′) and a spread of 3m (9′). It is attractive to wildlife.
Buckthorn is a close relative of the shrub known as Cascara sagrada (Spanish for “sacred bark”), Rhamnus purshiana.
Buckthorn will grow in any soil, even very alkaline soil, and anywhere not in complete shade. It’s happy in dry or moist soil, so it is a good survivor in most conditions.
The part most often used in medicine is the fruit, although the bark can be used instead. As it’s dioecious, to obtain fruit you will need at least two plants, one male and one female.
The specific name cathartica and the name purging buckthorn refer to its use as a purgative (a strong laxative). This is virtually its only medicinal use, though it is also diuretic, but this probably goes unnoticed alongside the laxative effect.
Please note that buckthorn is not suitable for use by children, pregnant or nursing women, also people suffering from Crohn’s disease or obstructions of the bowel.
Do not take buckthorn for more than 7 days in a row.
Adults can eat 8-15 ripe fruits to benefit from the effects, but these can be quite violent. For a more manageable result, you can make a standard infusion using 15g (a half ounce) crushed semi-ripe fruits to 250ml (1 US cup) boiling water. Leave to infuse for 30-60 minutes, then drain off and discard the fruit before use. Up to 1 cup a day is the maximum dosage, which may be split into 3 individual doses.
You can also use the bark for the same purpose. This must be dried in the shade for at least 1 year and up to 3 years before use, or you can dry it out in a very cool oven for a few hours. Don’t use fresh bark, as it will cause diarrhea and vomiting. To make a decoction of bark: Put 30g dried aged bark in a small saucepan and add 2 cups of cold water. Bring to the boil, turn down to a simmer and continue cooking until the liquid is reduced by half. Strain off and discard the bark and take the liquid either as a single dose or split into three. Max. 1 cup a day.
Buckthorn is native to the UK and across Europe, but it was taken to the USA by settlers, apparently for use in landscaping and has subsequently been so successful that it’s become an invasive weed, and therefore banned in some states and in Ontario, Canada.
Various dyes can be obtained from the bark, but I have no information on the mordants you need to use, though it would probably be interesting to experiment if you like natural dyes.
Remember that if you’re growing herbs for medicinal use, it’s important to use organic growing methods to ensure that you don’t accidentally include noxious chemicals in your remedies. To find out more about growing organic herbs visit the Gardenzone.