Overview
Alder Bonsai (Alnus species) is a water-loving deciduous tree with catkins, textured bark and natural riverside character. It is best suited to naturalistic woodland, clump and waterside-style bonsai. For UK growers, treat it as: Outdoor.
Placement
full sun to partial shade
Watering
keep consistently moist; alder tolerates wetter conditions than many bonsai but still needs oxygen at the roots
Feeding and fertilising
feed modestly during active growth
Pruning and wiring
clip back strong shoots and manage coarse growth
Repotting
repot every 2 years in early spring while vigorous
Propagation
seed and cuttings for some species
Pests, diseases and common issues
drying out, leaf beetles, aphids and coarse internodes