Subject: Predicting flowering times

From: [email-masked] (Stavros Macrakis)
Date: 05 Oct 1995 16:24:08 GMT

In reference works and catalogues, flowering times are usually given
either as a particular calendar interval ("mid-May to mid-June") or as
a season ("early summer").  These times usually refer to the "home
territory" of the reference work or nursery.

Is there any reasonable way to predict flowering times as a function
of microclimate?  I would think that most plants would fit into one of
a small number of schemata, e.g.:

  -- 20 days after a period of 10 days over 40 F
  -- 200 degree-days (base 40 F)
  -- 10 days after day length reaches 10 hours
  -- 60 days after ground temperature reaches 45 F

and there are surely enough data in the arboreta and botanical
collections to calculate such things.

Is flowering time in fact easily predictable from microclimate?

If so, where can I go to find this information for a given plant?

	-s

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From: Gilles Guerin <[email-masked]>
Date: 5 Oct 1995 17:27:53 GMT

I'm not sure you'll find this kind of information easily. There is some 
data of this type for large industrial plants as corn, wheat, etc. and 
you may find some information in specialized books on industrial 
agriculture. Anyway for many plants (flowering ones eg) I don't think 
you'll find anything besides some unprecise indications as this is part 
of the "Art" of horticulture (close to industrial secret indeed). Maybe 
some thesis exist on this subject for botanical species. good luck.

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From: Dunmail <[email-masked]>
Date: 6 Oct 1995 08:42:11 GMT

>Is flowering time in fact easily predictable from microclimate?

In some plants flowering is controlled by temperature, however, in others 
it is related to daylength.  I guess that in some it is related to both.

Dunmail

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From: [email-masked] (Jari Oksanen)
Date: Fri, 6 Oct 1995 09:35:39

In article <[email-masked]> Gilles Guerin <[email-masked]> writes:
>From: Gilles Guerin <[email-masked]>
>Subject: Re: Predicting flowering times
>Date: 5 Oct 1995 17:27:53 GMT

>some thesis exist on this subject for botanical species. good luck.

Pollen scientists and medicine persons interested in allergic reactions have 
this information for many plants producing abundant airborne pollen. This is 
not only timing of onset, but intensity of flowering (= pollen production). 
There are monitoring networks in many countries, in some cases for several 
years. I've seen pollen forecasts for allergetic persons in tv news both in my 
native Finland and in my current residence Norway. I'm sure you can have this 
information for any western country. I don't know much about modelling 
(predicting) the flowering time. Traditionally, degree-day thresholds are 
used, and they are known for many plants. I know that there are some attempts 
to develop more precise predictive models combined with weather forecasts. I 
don't know whether these are available or have been published. However, I 
suggest you browse some botany web sites with palynological information (see 
lists of botany related URLs, pointers are reported regularly in this group). 
Naturally, you will have trouble finding any information on wild plants that 
are not wind pollinated. Cheers, 

--- Jari Oksanen, Tromssa, Ruija / Romsa, Norga / Tromsø, Norge

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From: Gilles Guerin <[email-masked]>
Date: 6 Oct 1995 12:43:31 GMT

And some (a lot) are sensitive to day/night temperature difference...