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[SHADEGARDENS] Lux in flux

Dear Sombreros,

With some of the criticism being directed at how plants do not feel emotion
most of you may have to admit that the topic was still within one of the
topics listed as Kosher. We are trying to define what shade is. And unless
one defines the terms first, how can we plunge into the topic?

The present method of measuring light in units lux (metric) and foot candles
(the amount of light one candle puts out measured from a l foot surface a
foot away) is used by theatre lighting people and by movie set designers.
Most modern hand-held photographic light meters will readily convert from
f16 or f5.6 to foot candles. For the purposes of light hitting a plant under
a tree  we would have to create a foot candle unit/time. Plants need a
certain amount of light over time.

In trying to determine what shade is anywhere there is another factor some
of us might not know about. This is the Inverse Square Law. The law states
that at a light intensity s at a distance d if you double the distance from
your light source you will need 4 TIMES the light not double. What this
means in lay terms is that plants placed under a tree get a rapid
deminishing light intensity as you move them closer to the trunk.

I am not smart enough to figure out what would happen to the light under a
20 foot maple as compared to the light under a 40 foot maple. Would the
light be the same?

Spanish sherry is Spanish sherry because the grape vines grow in very chalky
white earth that reflects back the light and heat. The back of Hosta
hypoleuca leaves are white for an opposite reason to reflect back onto the
cliffs the light and heat coming down on the mountainside where this hosta
grows in Japan.

Also not considered in measuring shade is the different types of light
spectra that hit plants as they go through red leaves, green leaves and
other types of tree leaves. The light at different latitudes and differing
pollution levels will also have a fluctuation in quality either toward the
blue end or the red end if the light is measured in degrees Kelvin by a
colour meter. Although I know nothing of growing plants under lights I have
seen different light sources advertised as full-spectrum. What would they
mean by that?

What is dappled shade? Mottled shade? I think these terms are not accurate
particularly when you are trying to grow Meconopsis grandis.

Alex
Vancouver Zone 7/8 but sometimes 6.
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