Start to look out for the first flowering of horse chestnut
first leaves falling
Beginning of autumn leaf fall, some bare twigs or branches.
Use mature trees (30 years old or more), as young trees show different responses. Even trees of the same species, close to each other can behave very differently.
If you are finding it difficult to decide when to record, wait until the event is occurring in three trees of the same species in close proximity to each other. Record the trendsetters rather than the extraordinary.
Leaves may fall off before you have recorded any significant colour change.This may be the species or the weather conditions. Don’t worry! Just record when the tree is bare.
The effects of drought: In dry summers some species such as beech and birch may show the effects of drought, which can be confused with the onset of autumn.These include early colour changes and shrivelling and falling of leaves. Record the date you see first tint whatever the cause.