In article ,
Emery Davis wrote:

I just used the hedge trimmer to cut dead flowers and long stalks off of
a well established hyssop, and to give it a better shape. It's still
blooming a little bit. But does anyone know when's the right time to cut
it back hard?

That's a big one! Any time from now until spring.

I can't keep any of those Mediterranean woody labiates going very
long, because they all die from root-rot. It's generally a good
idea to renew them regularly, and layering works well. But whether
'not very long' is 5 years or 50 is entirely dependent on the
conditions. I should do better, with well-drained soil, but I
don't - and I am pretty sure that it's some unidentified fungus.


Regards,
Nick Maclaren.