Re: Buddlejas, invasive and not

Hello all--

It's interesting to hear how these beautiful plants are invasive in some
parts of the world and not others. Some folks have expressed surprise that
they would be a problem at all -- I must say, it was a surprise to me too.
I've only grown B. davidii in my home garden for about 10 years, but in
that time I've had one seedling.  However, some other local gardeners have
masses of them.  The invasive-ness problem seems to be mainly in riparian
areas around here (western Oregon, in Eugene).  Putting all this together,
I'm guessing that the reason I don't have seedlings in my garden is that I
only water once every 2-4 weeks in the summer.  Perhaps people who water
more frequently have more seedlings, just like wild areas in
summer-rainfall climates and riparian areas in Mediterranean climates?  (As
Kaj mentioned, cold winters would get rid of most seedlings too.)  I'm
afraid I'm not suggesting xeriscaping as a way to prevent Buddlejas
spreading to wild lands, though -- birds will still eat the seeds, and drop
them in moist areas.

I'm quite heartened to learn that other species of Buddleja don't seem to
reseed as readily, and that efforts are underway to develop sterile clones
of B. davidii.  They fill a wonderful niche in our home gardens here in the
Northwest (besides being over-eager to fill certain ecological niches).
When I wrote my original post I was forgetting that in many areas it's
customary to cut them back to the ground in the winter.  Around here they
are evergreen, and people usually let them grow to a large shrub (around 15
feet or 5 meters tall and wide).  Myself, I love to let them grow tall, but
I limb them up to a multi-trunked small tree.  The light, dappled shade is
beautiful.  Of course the fragrance is lovely too, and a large part of
their attraction. I've been racking my brains without much success to think
of a substitute.  Ceanothus are not usually happy with the wet winter soils
in Eugene.  So what do folks think -- would it be ethical to try unknown
Buddleja species in the hope that they won't prove invasive, or,
alternately, do people have other suggestions for evergreen tall light
screens, tolerant of clay soils, preferably flowering or fragrant?  What a
workhorse those Buddlejas are!

Yours,
-- Susannah
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