mbb wrote:

My young sons' school has an (almost) surrounded quadrangle garden, a simple
lawned area with 3 or 4 mature buddlejas, a neglected pond, and some other
herbaceous beds.

I'm told that it's a pleasant area, but "the bushes don't encourage
butterflies". I know it's a subjective opinion, but might it be true? Are
there situations where the buddleja doesn't attract butterflies? Or is it
the local geography, perhaps?

regards, mbb

Butterflies definitely have strong preferences for different buddleia
varieties.

The last few weeks have been quite good in our back garden for
butterflies - we've had Painted Ladies, Red Admirals, Small
Tortoiseshell, Peacock, Meadow Brown, Gatekeeper and Large White. On
some occassions there have been 20+ butterflies in the garden.

We also have something like a dozen buddleia bushes, mainly 3-4 years
old. A very dark one is of absolutely no interest at all to butterflies.
They much prefer the "common" buddleia varieties but we have two right
next to each other with almost identical colour, both scent quite
strongly although the scent is different, even to my insensitive nose,
however, there have been up to a dozen butterflies on one and none on
the other. In fact, I don't think we have ever seen a single butterfly
on the one they don't like.

So, I would suggest that you need to collect seed/seedlings/cuttings
from bushes that are known to attract butterflies. And the effort will
definitely be worth it.
--
Larry Stoter