Succeeds in a sunny position in any moderately fertile well-drained soil. Grows well in heavy clay soils. Plants are hardy to at least -15°c. The sub-species I. britannica chinensis is the form used medicinally.

None known

Seed - sow spring or autumn in a cold frame. When they are large enough to handle, prick the seedlings out into individual pots and plant them out in the summer. If you have sufficient seed, it is worthwhile trying a sowing in situ in the spring or the autumn. Division in spring or autumn.

Moist meadows, streamsides, ditches, wet woods etc.