Depth and California bulbs

Michael Mace
Wed, 09 Nov 2011 21:19:03 PST
Jane wrote:


>> Always give Calochortus bulbs as much depth as possible. They descend 

rapidly during the growing season.


I wanted to add a bit more color to Jane's observation.  I've long suspected
that my standard 8-inch (20 cm) pots were not a good home for my California
native bulbs.  If I let them go a couple of years without repotting, I tend
to find the bulbs at the bottom of the pot.  If I wait more than a couple of
years, the bulbs are often dead, apparently due to running out of room.


I don't have the time/resources to build raised beds like Jane's, so last
year I bought some extra-tall "treepots" from Stuewe & Sons.  (I think
someone on the list had recommended them; nice call.)  The ones I bought are
eight inches wide, but 15 inches tall (40 cm).  They look like tall black
wastebaskets.  Last winter I tested several Calochortus and Dichelostemma
bulbs in them.


The results during the growing season were encouraging but not uniform.
Calochortus superbus, luteus, argillosus, and uniflorus all bloomed
vigorously.  But two bulbs of C. weedii made only short leaves but no
flowers.  And the Dichelostemas produced a few weak leaves and did not


However, when I repotted in summer the results were much more positive.
Both of the C. weedii bulbs had increased in size by a lot, which is what
Calochortus bulbs do when they are happy.  The Dichelostemmas were even more
surprising.  Some of the bulbs had stayed in one spot and made pups, while
others had dived deep.  By deep, I mean the bulbs had pulled themselves down
by about eight inches in a single season.  When I dumped the dry soil out of
the pot, it came out as a single clump, and in the soil you could see the
tracks left as the bulbs migrated over against the side of the pot and then
went straight down along the side.  It looked like you'd imagine an
earthworm tunnel would look, but at the bottom of each tunnel there was a


Why the bulbs did this, and how, I have no idea.  But I can confirm Jane's
statements that these things crave growing room.



San Jose, CA

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