Rain Lily dormancy

David Pilling david@davidpilling.com
Mon, 29 Oct 2018 10:32:06 PDT

Post from Charles Crane (which ended up in the wrong place):

With 55 species of Zephyranthes and 20+ of Habranthus growing in a 
variety of warm climates from marshes to semi-deserts, variation in 
growing season is to be expected.  Z. candida and Z. flavissima are 
evergreen and will grow throughout the year if it is not too cold or 
dry.  Habranthus tubispathus grows in the fall, winter, and spring in 
its native habitat, and typically enters summer dormancy even if 
watered.  Z. chlorosolen, Z. traubii, Z. longituba, Z. jonesii, Z. 
smallii, Z. refugiensis, and Z. pulchella all grow maximally in fall and 
spring, stay green in the winter if not frozen below about -6C (20-22F), 
and optionally go dormant in summer if it does not rain.   Z. pulchella 
in particular will flower and put up young leaves (not just extend the 
old ones) if soaked after a long dry spell in summer.  Z. drummondii and 
Z. lindleyana are also mainly fall-spring growers with frequent summer 
dormancy.  Therefore, I would encourage you to keep your Zephyranthes 
growing under lights during winter.  I keep mine in pots outside during 
the summer and bring them into a sun room (in the heated part of the 
house) when it threatens to freeze hard.

     If one cheats, one can get Z. candida, Z. flavissima, H. 
tubispathus, and perhaps others to survive a temperate winter outside. 
I have some of each within 15 cm (6 in) my south-facing house 
foundation, outside a heated basement.  Two years ago, they survived a 
night of -19C (-2F) with only a dusting of snow cover.  Last winter, 
they survived the cold snap around Jan. 1, when one night was -28C 
(-19F) and one high was -20C (-4F), but I had piled about 40 cm (16 in) 
of snow over them before the severe cold arrived.  They looked ratty 
each spring, but they flowered about a month late both summers, and the 
Z. flavissima and Z. candida are expanding with offsets.  However, the 
lower temperature limit for the bulbs themselves (i.e., in pots left on 
a deck) is about -10C (12-14F).

Charles Crane

West Lafayette, Indiana (zone 5b)

David Pilling
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