Fall bloom

John Lonsdale john@johnlonsdale.net
Thu, 11 Sep 2003 03:35:13 PDT
"I remember reading about integrated Pest management principles and 
counting the number of days that a certain temperature was reached.  
This could be used to calculate the appearance of pests and determined 
the timing for the application of control practices. 

So why no the same with colchicums or crocus for that matter.  I could 
be that after 45 days of days over 85 degrees  the flower  ripens and it 
is not so much the appearance of the cold but the length of time that 
heat was present.  I guess we will all have to go to the lab to wok this 

Arnold's comments about temperature thresholds and insect populations are
spot on.  It is an interesting point re. bulb flowering initiation but it is
contraindicated because the same fall flowering crocus and colchicum flower
much earlier in the UK than they do in the eastern US. This is despite the
fact that they have encountered fewer days at higher temperatures in the UK.
The UK doesn't have the continental type climate we have in the eastern US,
so the cool nights come earlier.  If number of 'heat days' was the trigger,
these bulbs would be flowering in the US long before their brethren in the

Of course we are even luckier here because a number of bulbs that do well
here don't flower well or at all in the garden in the UK because they don't
get warm enough to ripen flower buds at all!

Dr John T Lonsdale,
407 Edgewood Drive,
Exton, Pennsylvania 19341,  USA

Home:  610 594 9232
Cell:  610 476 0428
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Visit "Edgewood" - The Lonsdale Garden at http://www.edgewoodgardens.net/

USDA Zone 6b

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