Jim McKenney wrote:
------------------------
"This causes me to suspect that soil conditions that favor
pathogens may be as important - or perhaps more important - then the
soil
temperature itself.
I've come to the same conclusion here, John, at least with respect to
certain plants. As an example, I would cite the culture of the common
and
very beautiful Allium caeruleum. Because this plant is readily available
from bulb merchants and is also very inexpensive, it's hardly the sort
of
plant most of us give serious attention. If it fades away, it's easily
replaced.
I eventually realized that I rarely see this plant in local gardens, and
when I do, the plantings look recent. So I decided to do an experiment.
I
have a raised bed of the local clay loam. I planted two dozen bulbs of
the
allium The first year results were, as usual, wonderful. Once the seed
started to ripen, I covered the alliums with a sheet of glass for the
rest
of the summer; the glass was removed in the autumn. The next year the
plants
returned in numbers and there was plenty of bloom.
This went on for several years, with the onion clump becoming thicker
and
more floriferous each year.
In 2008 I decided to test the hypothesis; I didn't cover the plants for
the
summer. The next year there were no blooming plants and very few plants
at
all. The last time I looked last summer, there were none.
=============================================
Very interesting Jim, I might have to give this a try. It is important
to note, there are different forms of A. caeruleum in cultivation. The
ones typically available from Dutch bulb growers behave exactly as you
say, does fine the first year after planting and disappearing in a few
years. This form is dark blue flowered, and invariably has a few barely
noticeable bulbils in the inflorescence, and curiously enough, often
sprouts some anomalous florets (more than 6 petals, fused flowers, or
cases where a stamen morphs into a pedicel producing a secondary flower
of small flower cluster, amusing).
There is a form being grown at Denver Botanic Garden (I refer to it as
the DBG form) that grows taller, has larger heads of a bright medium
blue, no bulbils in the inflorescence at all, no weird little anomalous
flowers. Overall, it is showier and longer lasting than the
commercially available form. And, there are uncommon forms that are
much more bulbilliferous, where as many as half the flowers are replaced
by red bulbils (see link). Jim, we discussed this once before, and your
plants looked very fine in a photo you showed once.
In my trials, when I received bulbs of this onion from DBG, the bulbs
prospered in only two out of several locations planted. I suspect it
does indeed like hot dry soil, but a heavier clay soil is better than
one too sandy. This form is also prolific with basal "bulblets" (as
distinct from inflorescence-borne "bulbils"), which I've been harvesting
and planting out around the garden, with the hope of one day creating a
scene like that at DBG (see my links), with many blue knobs poking out
among the general rock garden beds of lower plants (see links).
Allium caeruleum DBG and bulblets (baby bulb offsets produced around the
parent bulb and stem-bases)
http://www.srgc.org.uk/smf/index.php?topic=5766.msg161642#msg161642
http://www.srgc.org.uk/smf/index.php?action=dlattach;topic=5766.0;attach=229095;image
http://www.srgc.org.uk/smf/index.php?topic=5766.msg145871#msg145871
Allium caeruleum form with lots of bulbils
http://www.srgc.org.uk/smf/index.php?action=dlattach;topic=5766.0;attach=236923;image
Mark McDonough
Alpine-L co-list-owner
[email protected]
Massachusetts, USA
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