Requires a rich damp soil in a sheltered position[200] and plenty of moisture in the growing season[200]. Plants are very hardy, tolerating temperatures down to about -20°c[195], but they dislike prolonged exposure to hard frosts[200]. Plants can reach 10 metres in height in the warmer parts of Britain. This species is notably resistant to honey fungus[200]. Plants only flower at intervals of many years. When they do come into flower most of the plants energies are directed into producing seed and consequently the plant is severely weakened. They sometimes die after flowering, but if left alone they will usually recover though they will look very poorly for a few years. If fed with artificial NPK fertilizers at this time the plants are more likely to die[122]. A very ornamental plant, it will in time form a clump 7 or more metres in diameter so it is best grown in an isolated position[11]. This is a good companion species to grow in a woodland because the plants are shallow rooted and do not compete with deep rooted trees[195]. The rootstock is running[25], it is not too invasive in the cooler British climate[200] but can wander a little. New shoots appear from early April[25]. The plant is heat tolerant in zones 12 through 1. (Plant Hardiness Zones show how well plants withstand cold winter temperatures. Plant Heat Zones show when plants would start suffering from the heat. The Plant Heat Zone map is based on the number of "heat days" experienced in a given area where the temperature climbs to over 86 degrees F (30°C). At this temperature, many plants begin to suffer physiological damage. Heat Zones range from 1 (no heat days) to 12 (210 or more heat days). For example Heat Zone. 11-1 indicates that the plant is heat tolerant in zones 11 through 1.) For polyculture design as well as the above-ground architecture (form - tree, shrub etc. and size shown above) information on the habit and root pattern is also useful and given here if available. An evergreen. The plant growth habit is a runner spreading indefinitely by rhizomes or stolons [1-2]. The root pattern is rhizomatous with underground stems sending roots and shoots along their length [1-2].