Whilst studying the RHS General, I got told the same thing. The group
could not find dates on talc products. The only product we found that
did have a date on it was a gel from Clonex, which has a date on it. I
got some via mail order, but only had 3 months on it. They had a stand
at Gardeners World, so begged the question. The gell is blue and goes
brown when it looses its effectiveness, the date provides guidance.
If only the talc was so clear.
As far as talc based producs went, we concluded it was best to by in
season, when the was more than the odd pot on the shelf, then take from
the back (so synical us lot!)
Clifford