Encouraging Calochortus to Set Seed

Michael Mace michaelcmace@gmail.com
Thu, 15 Aug 2013 10:47:20 PDT
Chris wrote:

>> A capsule develops (sometimes to full size) but stops developing before
the seed matures.  I am wondering if this is common

I'm not really an expert, but I have some experience, so let me speculate.

In my experience it's not common for Calochortus to abort their seed pods
like this when the bulbs are completely happy.

I've seen Calochortus bulbs in pots abort their pods when the pot dries out
a little early while the seeds are maturing (for example, I had that happen
this season with one pot of C. argillosus that was in full sun). What seems
to happen is that if the pot dries out too much while the seeds are
developing, the bulbs immediately stop putting energy into the pods. They
just stop growing. They'll dry out, but they never open and often the seeds
inside are not mature when you open the pod.
I'm just speculating here, but I wonder if maybe your soil is drying out too
much during the seed maturation process. In nature, many Calochortus grow in
the ground in decomposed serpentine that can be surprisingly
water-retentive. I tried putting some of that soil in pots once, in an
effort to grow some rare Calochortus species. The soil stayed completely
goopy and waterlogged all winter, and then turned into a concrete-like
substance in the summer.

Even though your plants are in the ground, the adobe underneath them may be
so deep that the plants can't reach it to draw on it as a water reservoir.
So they're growing exclusively in the planting mix you created, and maybe
that's drying out too fast. I grew up in LA, and I can imagine the full sun
and low humidity sucking all the moisture out of your planting mix.

You could try a couple of experiments if you want:

--Create a different part of your planting bed with the adobe only about six
inches below the surface, so the bulbs can reach into that for moisture.

--Try watering one section of your growing area a few times as the seed pods
are maturing. In my experience, Calochortus bulbs are not too vulnerable to
rot from watering if they're still partially in growth. The time you really
don't want to water them is when they're totally dried out and brown, even
down to the stems.

Two other possibilities to think about: In California there are many small
beetles adapted to eating the pollen of Calochortus. They go along the
anthers like they're ears of corn, and strip off all the pollen. I've had
some plants stripped so thoroughly that they can't set seed. So you might
want to try some hand pollination.

The other question to ask is whether you're sure that you have genetically
different individuals of each species. I find it harder (but not impossible)
to get seeds from a single self-pollinated plant than from several
individuals crossed together. If you got your bulbs from one of the mass
market bulb companies, they might all be genetically identical clones.

Hope this helps.

San Jose, CA

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