In article ,
Kay wrote:

Hmm. I'm trying to get my head around that. Buddleia davidii flowers
late (August or so by memory - certainly no signs of flowers yet).
Therefore, rather than the rule of thumb 'prune just after flowering',
it's better to prune in spring. I usually tidy mine up in autumn and
prune right back early in the year. At least I think that's what I do!
So if spring pruning is OK, why would winter 'pruning' by frost damage
flowering at all? Or are you saying that if your flowering period is
earlier, so that you can prune after flowering and still get in some
growth that season, *and* that growth survives over winter, then you
will get flowers even earlier the following year?

Yes.

My comment was specifically against cutting it RIGHT back to 1'. This
often has the effect of making it put a lot of effort into reshooting,
whereupon ALL of its younger growth might be killed, leaving only
very old growth alive. That will at least set it back severely and
perhaps kill it - yes, even buddleia.

Pruning it moderately would lead to a more modest shooting and, if
that were all killed, there would still be some middle-aged growth
for it to reshoot from.

The point is that cutting right back to very old growth is a major
shock. Not a problem. But, if the plant then busts a gut to
regrow and THEN is cut back again, it is a pretty rough treatment.
That is why the books recommend waiting until spring for such
extreme pruning.


Regards,
Nick Maclaren.