My greenhouse monitoring project hit a small snag when i
began to measure temperatures. It seemed easy, just place a
few thermometers inside and compare the effect of thermal
mass (water) on temperature. Well... this will describe my
first problem, finding an accurate thermometer.
I tried three styles of thermometers. They are constructed
like this:
1. mechanical thermometers using a expanding metal
to move a pointer. This is the most common type
found today.
2. mercury thermometers made with a glass tube.
3. electronic thermometers.
None of the mechanical thermometers were accurate enough.
The electronic ones were a little expensive and not as
durable. Plus they needed batteries and had problems in
humid environments. Overall, the old mercury thermometers
with a high-low indicator outperformed all others.
Quality thermometers at a low price were difficult to find
but this site has one (mercury) that works:
www.charleysgreenhouse.com
The catalog listings are generally not of much use
is determining quality. Some mechanical thermometers
are rated very high but the scale is so small they
can't be read. This includes some expensive weather
thermometers, compost thermometers, and soil thermometers.
The electronic thermometers did have one unique feature
that was intriguing. they can have multiple wireless
sending units feeding a monitor inside the house (makes
data gathering a breeze in any weather).
Eventually i plan to match the data up with charts like the
following and improve my gardening activities.
Temperature (F) optimum sprouting optimum growing
---------- ----------------- ---------------
95 cucumber
squash
watermelon
90 cantaloupe
85 broccoli eggplant
cabbage pepper
chard watermelon
eggplant
pepper
tomato
80 cauliflower tomato
75 lettuce cantaloupe
parsley cucumber
squash
70 celery broccoli
cabbage
cauliflower
65 celery
chard
lettuce
parsley
jeff
