Mariposa season

Michael Mace
Fri, 10 Jun 2011 14:15:57 PDT
Boyce asked:

>> How difficult are they in containers?

I would like to invite other growers to chime in, but here's my take:

Calochortus range from the Canadian border to Mexico, and from California to
Colorado.  So you can find species for a variety of climates.  But most of
them are from California, and those are what I'd call particular but not
difficult.  In other words, if you give them the conditions they want, they
are easy to grow in containers.  But if you don't get the conditions right,
they can be unforgiving.

In general, most California-growing Calochortus will take the same
conditions as winter bulbs from places like South Africa and Chile.  If you
grow winter-growing species bulbs like Moraea, Romulea, and Gladiolus, you
can probably grow Calochortus.  But you need to use deep pots and pay
special attention to keeping them *totally* dry in summer.

Specifically, they want:

--Deep containers.  You can grow them successfully in standard 8-inch / 20
cm pots (I've done it), but within a couple of years they dive deep in the
pots.  If they hit the bottom of the pot, they run out of growing room and
will die the next year.  People who dug them in the wild (I haven't done it)
wrote of finding a long series of shed bulb cases underground, each one
deeper than the one before.

--Summer dryness.  Some Calochortus species grow in areas that get a bit of
summer moisture, but the big Mariposas I wrote about are very intolerant of
any summer moisture.  In the UK, you hear about growers leaving the pots out
in the sun, under glass, to "cook" all summer.  If you try that in
California, where the sun is a lot hotter, you literally will cook the
bulbs.  Here you leave them in the shade and let them stay ruthlessly dry,
with absolutely no rain or sprinkling from a hose, from dormancy until the
rains start (late October/early November).

--Good light and moisture in winter.  Their light and water needs are very
similar to mediterranean-climate bulbs.  They need a well-drained mix (I use
50-50 peat and sand, with some inorganic bulb fertilizer).  Do not skip the
fertilizer, and do not use organic products like chicken manure as they
encourage rot.  As long as drainage is good they like a lot of moisture when
in growth.  They also like a lot of sun, which I suspect may be a challenge
in some winter climates.

--Cool conditions, but not frozen.  Again, this is similar to other
mediterranean bulbs.  The ones I grow are very hardy to around 20F, but do
not appreciate long periods of freezing.  On the other hand, they seem
happiest with winter coolness and good air circulation.  Seedlings will damp
off if they are too humid/warm.  I suspect that in a heated greenhouse
geared to tropicals you'd get rot.

Some very beautiful Calochortus species come from the Great Basin area and
are adapted to extreme winter cold.  These grow like some Asian Tulips --
they want to be cold and dry in winter, and then in spring will grow very
quickly, blooming in early summer before they go dormant.  I can't grow them
easily because I don't have enough winter cold, but for someone in a very
cold winter climate they might actually be easier.

The now-defunct Calochortus Society collected a huge amount of data on
growing these things. They gave permission to reprint their findings, and
you can read them on the PBS wiki here:…

Hope that helps.

San Jose, CA

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