Can't answer your question but my montana has a grand total of 6 flowers
this year!
Unless you cut it back you will get fewer flowers each year.
Cut it hard back after it has finished flowering. Next years flowers will be
on the new growth it puts out this year. If it's a large montana then you
will be in for a treat next year.
--
Drakanthus.
(Spam filter: Include the word VB anywhere in the subject line or emails
will never reach me.)