Tuberous comfrey
Symphytum tuberosum
Family: Boraginaceae
What it is like
Symphytum tuberosum is a PERENNIAL growing to 0.6 m (2ft) by 0.6 m (2ft in) at a fast rate. See above for USDA hardiness. It is hardy to UK zone 5. It is in flower from May to June, and the seeds ripen from June to July. The species is hermaphrodite (has both male and female organs) and is pollinated by Bees. Suitable for: light (sandy), medium (loamy) and heavy (clay) soils and can grow in heavy clay soil. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils. It can grow in semi-shade (light woodland) or no shade. It prefers moist soil.
Height (m): 0.6
Where it is found
Woods, scrub and by rivers.
Europe, including Britain, south and east from Germany to Spain, S.w.Russia and Turkey.
Conservation Status:
Countries/locations it is found in
How it is used
Food
Rating: 2
When roasted until brown and brittle, and then finely ground, the root is used as a coffee substitute. It has a smoothness that is not found in real coffee.
Coffee: the various substitutes that can be used instead of coffee.
Medicine
Rating: 0
Other
Rating: 3
A good, and sometimes rampant, ground cover plant for a shady border or woodland.
Food Forest: Plants for Edible Forest Gardens and Food Forests.
Ground cover: Ground Cover
How it is grown
Tolerates most soils and situations but prefers a moist soil and some shade. Grows well in heavy clay soils. Hardy to about -20°c. Plants form extensive patches, spreading by means of a creeping tuberous rhizome. Plants are dormant in summer.
Propagating it: Seed - sow spring or autumn in a cold frame. When they are large enough to handle, prick the seedlings out into individual pots and grow them on in the greenhouse for their first winter. Plant them out into their permanent positions in late spring or early summer, after the last expected frosts. If you have sufficient seed you can try an outdoor sowing in situ in the spring. Division succeeds at almost any time of the year. Simply use a spade to chop off the top 7cm of root just below the soil level. The original root will regrow and you will have a number of root tops, each of which will make a new plant. These can either be potted up or planted out straight into their permanent positions.
Best place to grow: Woodland Garden Sunny Edge; Dappled Shade; Shady Edge; Ground Cover;
Habit: Perennial
Hardiness: 4-8
Growth: Fast
Soil: Light (sandy), medium, heavy (clay)
Shade: Semi-shade, no shade
Moisture: Moist
Things to keep in mind
No reports of toxicity have been seen for this species, but the following reports have been seen for S. officinale. This plant contains small quantities of a toxic alkaloid which can have a cumulative effect upon the liver. Largest concentrations are found in the roots, leaves contain higher quantities of the alkaloid as they grow older and young leaves contain almost none. Most people would have to consume very large quantities of the plant in order to do any harm, though anyone with liver problems should obviously be more cautious. In general, the health-promoting properties of the plant probably far outweigh any possible disbenefits, especially if only the younger leaves are used.