Read the season, not the calendar
Shorter days and cooler nights change growth, but timing varies by latitude and year. Temperate trees begin hardening growth and preparing for dormancy; tropical species may instead need protection from falling temperatures. Identify the tree and follow local phenology.
What can be useful
Inspect for pests and disease, remove dead or damaged material, check wire and stabilize pots before storms. Review whether branches need positioning while they are still flexible. Major structural work is not automatically appropriate; weak, recently repotted or late-flushing trees may need recovery rather than more cuts.
Water and feeding
Continue checking moisture while growth slows. Cool weather does not eliminate water needs, and wet substrate in cold conditions can harm roots. Adjust fertilizer to the species and growth stage; do not push soft growth that cannot harden before frost.
Make a winter plan
Know where each tree will overwinter, how its roots will be protected, and how you will check water during dry spells. The right autumn task is often preparation and observation, not intervention.
This page is reconstructed from historical BlogBonsai material. Horticultural details should be interpreted for the species, season, climate and condition of the individual tree.