The last month’s ground temperatures:
The “Garden” trace comes from a waterproof Hobo datalogger buried a few inches underground, beneath a thick layer of chipped leaf mulch. The “Patio” trace comes from the center of the cramped space below the concrete patio, buried flush with the bare dirt floor. The “Water” trace is the temperature at the incoming water pipe from the town water main, which passes 150 feet under the front yard.
Calculated eyeballometrically, the temperature rose 7 °F in about a month.
The datalogger in the garden came from the “cold cellar” veggie storage buckets, so I don’t have a year-long record. On the other paw, it looks like the patio temperature will be a pretty good proxy for the minimum garden temperature.
I hand-cleaned the Hobo CSV files and fed the results into a Gnuplot script that’s replete with the cruft of ages:
#!/bin/sh
#-- overhead
export GDFONTPATH="/usr/share/fonts/truetype/"
ofile=Temperatures.png
echo Output file: ${ofile}
#-- do it
gnuplot << EOF
#set term x11
set term png font "arialbd.ttf" 18 size 950,600
set output "${ofile}"
set title "Ground Temperatures"
set key noautotitles right center
unset mouse
set bmargin 4
set grid xtics ytics
set timefmt "%m/%d/%Y %H:%M:%S"
set xdata time
set xlabel "Date"
set format x "%Y-%m-%d"
set xrange [:"07/15/2014"]
set xtics font "arial,12"
#set mxtics 2
#set logscale y
#set ytics nomirror autofreq
set ylabel "Temperature - F"
#set format y "%4.0f"
#set yrange [30:90]
#set mytics 2
#set y2label "right side variable"
#set y2tics nomirror autofreq 2
#set format y2 "%3.0f"
#set y2range [0:200]
#set y2tics 32
#set rmargin 9
set datafile separator ","
#set label 1 "Garden" at "05/31/2014",25 left font "arialbd,10" tc lt 3
#set arrow from 2.100,110 to 2.105,103 lt 1 lw 2 lc 0
plot \
"Garden.csv" using 2:3 with lines lt 3 lw 1 title "Garden",\
"Patio.csv" using 2:3 with lines lt 2 lw 1 title "Patio",\
"Water.csv" using 2:5 with lines lt 4 lw 1 title "Water",\
EOF
