What makes Amaryllis hybrids bloom?
John Grimshaw (Tue, 25 Aug 2009 02:29:54 PDT)

It is difficult to make useful comments on plants growing in other
conditions, and without keeping detailed observations over a series of
years, but here in the UK winter moisture is not a problem (!). What I think
is important for any winter-growing bulb is that the foliage is able to
expand and function to its maximum ability, enabling it to photosynthesise
at the most efficient rate possible and thus build up the bulb. In a dry but
essentially mild climate this might mean the effect of good winter rains
enabling good leaf development: in a wet but chilly climate this may mean
the avoidance of leaf damage by frost. It would be interesting to correlate
Amaryllis flowering here with the severity of the winter preceding (or
perhaps that should be winters).

The length of time a bulbous plant is in active growth is obviously
important: if it dies down quickly in spring due to early drying-out of the
soil it will not have been able to fatten up as much as one that stays green
for longer.

When does Amaryllis normally go dormant for members in different parts of
the world? I noticed yesterday that a patch of bulbs below a south-facing
wall here at Colesbourne was still in full lush leaf (and thought that we
aren't likely to get any flowers!), undoubtedly due to the persistently damp
and cool summer we've had. I would normally expect them to be dormant from
about June onwards.

John Grimshaw

Dr. John M. Grimshaw
Sycamore Cottage
Colesbourne
Cheltenham
Gloucestershire
GL53 9NP

Tel. 01242 870567