Re: CULT: Companion plants

The subject of companion plants for TBs is a thorny one.  I would agree
that daylilies are a bad match for TBs.  Not only are the cultural
requirements different but the robust foliage of the daylilies can smother
the irises.  On the other hand, I have found that Siberians and daylilies
are better matched in terms of vigor and requirements.  Ditto for spurias,
if one selects varieties that are adapted to more summer moisture.

As TB companions, I like early tulips and daffodils for first color.  They
are planted deeply (and therefore do not compete very much with the iris
roots) and do not produce too much foliage--which is gone near the end of
the iris season, anyhow.  The negative is that the foliage is often
unattractive during the iris bloom season.

A good choice for later color would be any kind of lily--Asiatics,
Orientals, or Trumpets.  The stem-rooting types are not as good with irises
because they thrive best when well mulched with loose organic matter.  That
would encourage rotting in the iris rhizomes.  The foliage contrasts with
the iris leaves rather nicely.  The Asiatics would follow closely after the
latest irises, the Trumpet types next, and lastly the Orientals.  Again,
these will do better with siberians and spurias.  Spurias, however, bloom
about the same time as the Oriental hybrid lilies and one should pay some
attention to the color scheme, using the irises to provide the blues and
purples not available in the lilies.

Invasive perennials like most Lysimachias, Monardas and Oenotheras
(particularly O. rosea or O. berlandieri, now trying to take over large
areas of my garden) are to be avoided among irises.

My favorite for companion planting with TBs, however, is columbine.  The
airy foliage and the small, delicate flowers blooming with irises make a
wonderful picture.  Columbines self-seed enthusiastically.  I have over the
years grown a half-dozen strains in my garden and they have crossed amongst
themselves to produce a range of types fromthe compact, up-facing
Biedermeir types to the large-flowed McKana or Music varieties, and even to
some very tall ones with pendant blooms that seem to derive from the local
native A. canadensis and 'Magpie,' a stunning black-and-white English
variety.  And I can't help but put in a note of strong dislike for 'Nora
Barlow,' with its weakly colored pinkish green wads of double bloom.  Yecch!

In selecting annuals, again be careful of any that produce smothering
foliage or self-seed so as to become weedy.  A few years ago I unwisely
used Melampodium, which overgrew the irises and is still a problem coming
up from seed.  California poppies seem to work well, as do the little
violas called 'Johnny-jump-ups.'  Undoubtedly there are many other choices.

One of the real problems with TBs, in my opinion, is their unsuitablility
as mixed border plants unless you exercise eternal vigilance.  Some of the
lesser bearded types with more vigor, and siberians, are better choices for
gardeners who are interested in a wide variety of plant types and don't
have room for a dedicated TB bed.  Spurias are the top iris in my opinion
for border planting, provided you choose wisely.  Louisianas can also hold
their own in a moist mixed border.

Bill Shear
Department of Biology
Hampden-Sydney College
Hampden-Sydney VA 23943
(804)223-6172
FAX (804)223-6374
email<bills@tiger.hsc.edu>
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