pushing envelopes - 3 variants

James Waddick jwaddick@kc.rr.com
Sun, 27 Jun 2004 06:37:22 PDT
Dear All;
	A couple related topics:

	Provenance.	This is seemingly little known term, but of 
utmost importance in regard to hardiness and micro-climates. It 
simply means 'origin' but more important it refers to the exact 
location where a plant originated. When you look closely into the 
origin and distribution of many perennials including bulbs, it is 
often surprising that all of our plants of a single species in 
cultivation may come from a single or limited collections from the 
wild. Often these collections come from the middle of a species' 
range and do not represent the hardiest or most northern (or southern 
in Southern hemisphere) population.
	Ocassionally a plant is introduced from northern regions of 
its distribution and found to exhibit unexpected increased hardiness.

	Jamie, Uli and others mention that some Crinum remain 
evergreen or barely loose foliage in winter in their climate. Here 
ALL Crinum outdoors loose their foliage every winter*, but all 
produce new foliage. The fact that some Crinum loose all foliage and 
others just have damaged foliage suggests the range of hardiness or 
cold tolerance.
	I have heard of some gardeners in mild climates who purposely 
cut foliage and stems at the onset of winter to 'push' plants into 
moving their metabolism into dormant bud production. Plants that are 
allowed to remain evergreen or nearly so, may not develop the deep 
dormancy regarded to increased hardiness. By removing the foliage, 
the plant goes into full dormancy and increases tolerance to cold.

	The relationship between dormancy, degree of herbaceous-ness 
and evergreen-ness all indicate a range of hardiness. I suppose one 
can envision a plant natural growing in a mild climate, but getting 
an early hard frost and defoliating quickly. Later hard frosts have 
little effect.	Nearby in a more protected area another plant may 
just have damaged foliage, but then be more prone to greater damage 
later in the cold season because it did not go totally dormant early. 
Which leads to....

	As a totally alternate way of discussing cold hardiness, one 
might relate known ecology of a plant to its probable cold tolerance; 
i.e. the more we know about how a plant grows in the wild, the better 
we might know how it might behave in the garden. (Warning Commercial 
Plug!) In my recently published book on the genus Paeonia* (peonies) 
I have avoided the use USDA Zones in favor of discussing the native 
climate, geography etc. I have rated each species as 'northern', 
'temperate' or 'mild', but then given some details about specifics.
	We often see a situation where a plant has a very restricted 
range today, but in the past had a much larger distribution and this 
is reflected by its extended hardiness. A peony example in general 
regards tree peony species which are almost totally confined to near 
tropic locations in SE China, yet are perfectly happy growing in 
northern climates including southern Canada, Scandanavian countries 
etc. Not what you'd expect from a sub-tropical species. This suggests 
that the current restricted range reflects some conditions other than 
cold tolerance - we know they have been dug for medicinal purpose for 
millennia and continue to have human pressure on them in nature.

	What this all means is that there are many variable to 
growing plants that may not seem obviously hardy. Temperature is just 
one of a palette of conditions relate to hardiness. Provenance, 
cultivation techniques and understanding can overcome some of what 
may seem obvious. Nothing is obvious and instead of curtailing 
experimentation, should encourage the 'adventurous' gardener to try 

	Best	Jim W.

Dr. James W. Waddick
8871 NW Brostrom Rd.
Kansas City Missouri 64152-2711
Ph.    816-746-1949
E-fax  419-781-8594

Zone 5 Record low -23F
	Summer 100F +

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