Monarch Watch Blog

How Does Your Garden Grow?

Friday, February 29th, 2008 at 7:55 pm by Chip Taylor
Filed under Degree Days | No Comments »

My interest in monarchs and monarch population dynamics is causing me to pay much more attention to the weather and to climates than I ever have before. Indeed, I’m now on a mission to educate those of you who might be interested in how weather influences plant growth and monarchs. For my own education and to record the growing degrees days, we’ve installed two Monarch Watch Temperature Loggers in our garden, Monarch Waystation #1.

Temperature Logger

The Temperature Loggers are small, relatively inexpensive, programmable recording temperature sensors. These reusable devices have a long battery life and can be used to record temperatures at defined intervals for days, weeks or even months. I recently downloaded the data from these loggers so that I might compare the temperature data from the garden with that recorded at the local airport and with the monthly mean temperatures for Kansas provided by the NOAA.

Winter is traditionally defined as the three-month period encompassing December, January, and February. The records listed in Table 1 are from 3 December 2007 until midday of the 25th of February. Our loggers were set to record the temperature every hour and to rollover and start a new record when the data limit has been reached, in this case in about 86 days. Unfortunately, rollover occurred – resulting in the loss of the earliest data from the first two days of December. Nevertheless, the data given for December and for the first 24.5 days of February should be close to the actual means for these months. Overall, the means are remarkably similar for each of these three months.

Table 1. Winter temperatures (2007-08) for Monarch Waystation #1, Lawrence, KS.

Temperature December January February
Max. Mean 41.3 42.6 42.3
Min. Mean 18.7 15.5 17.0
Mean 28.6 28.2 28.7

The mean temperature for December 2007 for Kansas, as found via the NOAA site, was 31.9F making December 2007 the 6th coldest over the last 30 years. The mean temperature for January was 28.9F, a bit warmer than the long time average and 11th coldest January among the last 30. These data are not yet available for February but this month has also been a bit colder than average. When all the data are assembled, this winter will measure as a tad colder than average. The mean temperatures for the garden are a bit colder than those for the state but this is not surprising since we are located in the northeast corner of a rather large state.

Of greater interest is the comparison of the garden temperature with those recorded for the official weather station for Lawrence (Table 2).

Table 2. Official winter temperatures (2007-08) for Lawrence, KS.

Temperature December January February
Max. Mean 39 37 38
Min. Mean 19 16 18
Mean 29 27 28

Interestingly, both the means highs and mean lows for the garden are consistently higher and lower for the garden than for the official weather station. The monthly means for January and February were at bit higher for the garden than those of the weather station. These differences are probably due to the location of the garden. The garden is in a slight depression and is protected to some degree from the wind, perhaps allowing heat to build up slightly during the day. However, being down-slope and in a slight depression, the area is subject to cold air drainage, perhaps accounting for the lower nighttime temperatures than at the official weather station. The differences between the two locations, though seemingly small, could have an impact on plant growth. We will compare the growing degree days through the season for both locations and will let you know if these differences are really significant.

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