On 31/08/2019 09:49, Broadback wrote:
From the garden point of view? When I was young, a long time ago, it
started on the 21st Of September. Now the weather men talk of
Meteorological commencing the 1st of September. I have seeds which
require to be sown in the Autumn. When is the best time for this please?

Astronomical autumn starts on the equinox (21 September, more or less).
Meteorological autumn starts on the 1st September. The Wikipedia article
gives some other alternatives - 1st August, 7th August, first Monday of
September.

I think of the first two or three weeks of September as transitional
from summer to autumn - in some years they are summery (an Indian
Summer); in other years they are autumnal.

The other end of autumn is also variable - in 2009 winter arrived at the
start of November, but in many years it extends well into December.

The best time would depend on the species, the area, and the weather,
but in the absence of data October seems a good compromise.

--
SRH