Colchicum luteum

John Grimshaw
Wed, 21 Jan 2004 23:07:26 PST
Jim McKenney is suggesting putting Colchicum luteum into the refrigerator
after it has gone dormant. While I would never stop anyone experimenting,
one needs to think how these plants grow in the wild. As I understand it, C.
luteum has a huge distribution in Central Asia eastwards to Kashmir: all
areas that have a long hot summmer quickly followed by cold winters. The
Colchicums, I believe, emerge as the ground melts and do their thing quickly
before the summer heat comes on. The point is, however, that a long hot
summer is experienced, and I suspect that this is necessary to the plant's
physiology to trigger the initiation of new buds etc. It may well be
disrupted if the bulbs receive too long a chilling, especially at the wrong
time of year.

In the UK C. luteum has a reputation for being difficult to grow, and being
a martyr to botrytis. What happens is that they are planted in autumn and
watered like other bulbs. We have no cold weather worth mentioning (these
days especially) and the poor things come into flower in December, elongated
in the low light so they look quite terrible. Then the flower fades and
flops onto the foliage, and promptly develops botrytis, encouraged by the
high atmospheric humidity. This spreads into the foliage and in no very long
time, the plant is dead. To get round this I leave my pots of C. luteum and
C. kesselringii (another C Asian species) dry from the time the plants go
dormant until January, and repot them then. I did it just last Friday, 16
Jan, this year. The bulbs have a fringe of embryonic roots and the shoot is
well developed, so as soon as they are watered (as they would be with snow
melt in the wild) they develop rapidly and will be in flower within the next
few days. The growth remains compact and the plants grow with increasing
daylength and warmth. Botrytis remains a problem, but is much less so than
earlier in the winter. I have been growing C. luteum from Kashmir since 1989
and from Tadjikistan since 1991 (also C. kesselringii) so these 'difficult'
species can be maintained for a reasonable length of time. The biggest
problem with this method is to keep the plants growing long enough to build
up a decent new corm; a touch of dryness in about April will send them
promptly to dormancy. This obviously happened with mine last year, as they
are smaller than I really would like to see, but they're now back under my

What I would suggest is that the bulbs could be potted in autumn and allowed
to make some root growth, but are then put into cold storage until the
spring or late winter. But it would have to be cold, 1-2 deg C; any warmer
and they will grow!

John Grimshaw

Dr John M. Grimshaw
Gardens Cottage
Nr Cheltenham
Gloucestershire GL53 9NP


----- Original Message -----
From: "Jim McKenney" <>
To: "Pacific Bulb Society" <>
Sent: Thursday, January 22, 2004 2:37 AM
Subject: Re: [pbs] Five favorite yellow-flowered geophytes

> Here's what I'm about to try for Colchicum luteum and, should I be able to
> acquire another one,  Iris winogradowii: after the plants enter dormancy,
> I'll give them a few weeks at prevailing temperatures and then  try
> them in the refrigerator for the rest of the summer. The refrigerator here
> gets opened so many times a day that the temperature is probably in the
> 40s F much of the time, if that.

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