Climate (once again), Humidity

J.E. Shields
Thu, 17 Nov 2005 08:04:54 PST
There is a scientific approach to humidity as far as horticulture is 
concerned.  I don't have the specific reference anymore, but the 
investigator created an index of transpiration stress.  It involved 
rainfall and relative humidity both, as far as I can recall.

I think Lee Poulsen first called this humidity/transpiration study to my 
attention.  Lee, do you still have that URL?

There is a fairly regular gradient from the high humidity East Coast of the 
USA to the dry climate of the Rocky Mountains.  The rainfall/humidity are 
highest in the East, the transpiration stress is highest in the mountains 
of the West.

This index does not take into account the warm nights of the East vs. the 
cool nights of the West.  The nighttime temperatures are as important, even 
more important sometimes, than the transpiration stress for growing many 
South African bulbs.

Jim Shields
in central Indiana

Jim Shields             USDA Zone 5             Shields Gardens, Ltd.
P.O. Box 92              WWW:
Westfield, Indiana 46074, USA
Tel. ++1-317-867-3344     or      toll-free 1-866-449-3344 in USA

More information about the pbs mailing list