Usually, the first trees we see turning are the ash trees — especially the American ash, which has such wonderful deep purples and reds. The common ash’s leaves turn yellow at the same time, and they look amazing together. Currently we have good conditions: warm days, cooling off at night, which are ideal for autumn colour.
This year, however, because of the summer’s unusually high temperatures, we are seeing a staggered autumn. We aren’t getting the full blaze of colour all at once. Trees are dealing with the seasons individually, as they all have different drought strategies.
Many trees, including horse chestnuts, walnuts and tulip trees, lost their leaves sooner than usual in a “false autumn” and have already gone into early dormancy for winter. As a result of the summer drought, trees such as these lost too much moisture from their system, and their way of saving energy is to drop their leaves. English oaks, on the other hand, aren’t even starting to go into autumn. They’re still holding on, using these unseasonably warm autumn days to store up energy for hibernation in order to bud next spring.