crocosmias
Mary Sue Ittner (Mon, 12 Oct 2015 19:42:25 PDT)

Crocosmias increase many different ways and for
that reason are considered to be invasive by
many. Crocosmia × crocosmiiflora has become an
exotic weed in places that remain wet in
California in the summer (drainage ditches,
watered gardens.) As Vivien has pointed out the
old corms do not shrivel away, but I believe only
the top corm probably produces a flower. David
Pilling has added a photo of stacked corms on the wiki.
http://pacificbulbsociety.org/pbswiki/index.php/…
But if you are trying to get rid of them (I'm
experienced with this) and think you have gotten
all of them out, you may have just pulled the top
corms off and what is left is capable of blooming
once the newer corm is removed. When I lived in a
warmer sunnier summer location I tried to get all
of them out of perennial beds when they were
taking over and the next year there were still
leaves and flowers. So perhaps this was one way
of keeping them in hand. As Vivien also noted,
the corm sends out runners in more than one
direction and each runner creates new corms as it
runs. The new corms probably have to get a
certain size before they bloom, but I don't know how big that might be.

I should have taken a photo of the runners for
the wiki the last time I dug them out. In my dry
and shady summer garden they don't bloom much, so
I'd just have a lot of leaves and no flowers if I
left them and in time more and more of them so I
dig them out. And when I think they are all gone,
in later years I find them again so obviously I
didn't get them all. I don't know if all the
species and cultivars behave in this same way.
Photos on the wiki from David Pilling show some
large flowering clumps. I wonder how many corms there are in that patch.

Mary Sue