minimum temp for Nerine?
Max Withers (Mon, 30 Aug 2010 16:34:10 PDT)

David linked to Graham Duncan's _Curtis's_ article on N. ridleyi,
which described that plant's environment thusly "Occurring at high
altitude, the plants are sometimes subject to snowfalls and sub-zero
temperatures for several days at a time in winter."

Duncan's subsequent summary of "the Dutch research" (Van Brenk,
G. and Benschop, M. (1993). Nerine. In: De Hertogh, A. and Le Nard,
M., The Physiology of Flower Bulbs: 559--588) is therefore confusing:

Studies carried out in The Netherlands with N. sarniensis, the
second-most notorious species for erratic flowering performance, have
shown that initiation of a flower bud occurs every year in mature
bulbs at the beginning of the growth cycle, directly after flowering.
During the following growth cycle, the flower bud differentiates into
its component parts such as tepals and stamens and during the third
growth cycle the bulb flowers. The cycle therefore takes three years
from initiation to flowering and at the end of each growth cycle, a
mature bulb contains two flower buds at different stages of
development (Van Brenk & Benschop 1993 <#b8>). These studies have also
shown that initiation of the flower bud in N.sarniensis is independent
of temperature, but that growth of the flower bud is greatly dependent
on it. The oldest flower bud will only develop and flower successfully
within a fairly high temperature range and the optimal temperature for
this to occur is between 17° and 21°C. If the temperature drops to
below 17°C, the flower buds are aborted (Van Brenk and Benschop 1993
<#b8>). These findings may or may not be relevant to N. ridleyi but
are mentioned here as a possible aid to inducing flowering in this
species. Like those of the three other winter-growing species, the
bulbs of N. ridleyi may well be stimulated to flowering in response to
fire, which could be simulated by burning a layer of straw or dry
leaves and twigs over the tops of the bulbs in late summer.

(This discussion is in the context of how shy N. ridleyi is to flower,
even in situ.) The temperature discrepancy can perhaps be explained if
the optimal temperature range described is for the dormant, i.e. summer
period? There is a further discrepancy about the number of years the
flowers take to form -- I believe Nick de Rothschild just said 2, not 3,
on this list. At any rate, I will endeavor to track down the original
work, unless someone has a copy handy.

I discovered another inaccessible article that I will also try to
procure is I ever have time:
Title: Bulb and inflorescence development in Nerine sarniensis
Author(s): Vishnevetsky J, LilienKipnis H, Azizbekova N, et al.
Source: ISRAEL JOURNAL OF PLANT SCIENCES Volume: 45 Issue: 1
Pages: 13-18 Published: 1997

As an aside, I am intrigued by the idea of a small fire to induce
flowering. Has anyone actually tried this? I think I will collect the
prunings from my Protea to simulate an authentic Fynbos burn.

Best,
Max Withers
Oakland CA