pH in plants

Kay Lancaster kay at hub.fern.com
Sat Mar 8 16:28:08 EST 1997


In article <01bc2bca$53d22380$4062fecc at default>, "Jeff" wrote:
>Hi
>	I'm not a scientist, just a firefighter with an interest in furthering my
>'green thumb'.  My house is a great medium for plant growth.  However,
>lately, I discovered that a recurrent problem in my fish tank was relative
>to the high pH of my well water. (>7.5).  Would someone with the
>appropriate knowledge ( and willingness to share it) explain the effects
>this may have on watering my plants?  I understand acid/base balance as it
>applies to homeostasis in humans.  I would appreciate any help....

Plants don't have the same sorts of homeostasis problems animals do (or
at least that's not the first problem they have with "out of range" pH).
Instead, they have problems absorbing certain of the nutrients they need
from the soil.  Whether or not this is going to be a real problem depends
on the kind of plants you're trying to grow, and the pH and "cation exchange
capacity" (a sort of buffer capacity) of the soil in the pots.  Most plants
prefer soil pH between about 6 and 7; plants in pH 5 or less soils, or in
soils with pH greater than 8 are probably going to have to be adapted to
those conditions.

"Bad water pH" is going to be a bigger problem for you if you're trying
to grow hydroponically, or if you're trying to grow in soil-less media
like "metro mix"; it will be much less of a problem with plants growing
in soils with good buffer capacity.

Ortho put out a good, slender paperback a few years ago with a title like
"soils and fertilizers" that did a nice job of explaining soil pH, 
CEC, mineral nutrient availability, etc.  You might want to look for it
at your library.  Or you may want to consult a good soils or basic agronomy
textbook for similar information.  Your cooperative extension office 
probably also has similar information, and can direct you to a soil
testing lab if you want to pursue this farther with your own plants.

Since the bionet groups are designed for scientists, you might want to
join us in rec.gardens, or on the gardens listserv  (listserv at lsv.uky.edu;
subscribe gardens your name).  Both are noisy, high volume groups with
lots of good gardeners with technical expertise to help you answer 
questions like this one.

Kay Lancaster    kay at fern.com  




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