Bonsai Training Information

Alnus incana
Grey Alder, Speckled Alder, Tag Alder

Grey Alder is a smaller tree than the Common Alder and will reach heights from 10 - 24 metres, depending on conditions. It has smooth grey shiny bark with very distinct pores. In older trees this may become duller and grow some fissures.


Formal upright, Informal Upright, Slanting, Cascade, Semi-cascade, Literate, Broom, Rock-over-root, Clasped-to-rock, Twin-trunk, Clump, Group planting, Saikei




Full Sun or Partial Shade. In summer protect from drying out and position in dappled shade area. In winter ensure the pot does not freeze. Store in a cool room or cover pot in bark and sphagnum.


It likes a moist soil, keep soils moist at all times. If allowed to dry out leafs will die and you may lose a branch or two.


Every 2 weeks days during growing season from mid spring to late summer. Use a balanced fertiliser.

Leaf and Branch Pruning:

Let the branches grow out till side shoots appear on the runner branch, before cutting back to leave a pair of side shoots. In younger trees you may not see this happening for a while, in which case you may need to prune back to leave 4 nodes on the branch once it has grown to about 8 inches.

Re-potting & Growing Medium:

Every 2 years at the begining of spring or in autumn. Prune roots no more than 20% off at any one time. Use a heavy clay soil 1 Part Loam, 1 Part Clay, 1 Part Sharp Sand. An alternative medium would be 2 Parts Akadama and 1 Part Pumice.


The branches are quite springy and not so easy to wire. It takes a few years of shaping with pruning before the branches are each enough to wire. If you need to wire best in spring but protect delicate bark.


Thrives on poor and even on chalkly soils but prefers a heavy moist soil. Grows well in heavy clay soils. This species has a symbiotic relationship with certain soil micro-organisms, these form nodules on the roots of the plants and fix atmospheric nitrogen.

More Images:

Print Bonsai Care Guide for Alnus incana