Encouraging Calochortus to Set Seed

Jane McGary janemcgary@earthlink.net
Fri, 16 Aug 2013 17:07:47 PDT
To address some of Chris's other concerns:

Probably Mike's suspicion of excessive drying is a good one. The mix 
Chris describes probably doesn't retain any moisture. Even though 
Calochortus often grow on slopes and in rocky ground, the main bulbs 
are deep in the soil and the plants are often surrounded by rocks, 
shrubs, and grasses that help the soil retain some humidity. Rather 
than adding a "water-retentive layer," I would suggest revising the 
soil mix to exclude peat (which dries out and is very hard to 
rehydrate) and bark (which I believe to be deleterious for most 
bulbs), and instead incorporating some sand (as coarse as possible, 
but with some fines) and loam or leafmold if it can be obtained. If 
it's not possible to replace the existing soil, Chris should sprinkle 
it lightly occasionally during summer -- just wave the hose at it. 
Also, a gravel mulch will help both to retain moisture and to support 
the stems. Although some Calochortus grow naturally in stiff clay 
soils, such as adobe, I have not found this necessary for any of 
them, or indeed for any California bulbs.

Calochortus bulbs move downward very quickly, e.g. 4 inches in two 
years. In many species new bulbils grow on the stems above the main 
bulb, and these eventually grow to flowering size, especially when 
the parent bulb gets eaten. You can hasten the process by detaching 
the bulbils and planting them a little distance away. I don't know 
how far the roots extend below the bulb as I have never lifted any 
when they were in growth, but I don't think it's very far as I didn't 
find them extending beyond the mesh baskets I grew some in. I 
wouldn't expect them to grow more than about 10 inches (30 cm) below 
the soil surface, though.

I have at least two Calochortus species (C. palmeri and C. dunnii) of 
which I have only a single clone, and they have produced fertile 
seed, so I suspect many or most are self-fertile.

All the Calochortus flowers are done here now, but I'm still waiting 
and waiting for the last two (C. plummerae and C. weedii) to ripen their seed.

Jane McGary
Portland, Oregon, USA

At 04:37 PM 8/16/2013, you wrote:
>Thanks Mike. I will test your drying-out theory this year.  Everything you
>read about Calochortuses tells you to make sure the mix is well-draining,
>and I have only ever seen them in the wild growing in very well-draining
>situations, so I may well have overdone it. a)      How deep 
>Calochortus roots tend to extend below the bulb (esp for
>the various Mariposas)?  In other words, how deep a water-retentive layer
>should I make?
>b)      How deep should I plan for the bulbs themselves to dig?  I forget
>which species dig in more than others, but I recall some of them pull
>themselves deeper each season.

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