Thermometer

I got a temperature and humidity data logger recently and have had it running outside the greenhouse for the past two weeks. The model is Elitech LogEt8THE, which does not have Bluetooth, so it needs to be plugged into a USB port to download the data. Although it will export to an Excel file, for some reason the data cells in the exported sheet are text, not numbers. Since I've been developing spreadsheets since before Excel even existed (Lotus 1-2-3 was the market leader when I started in 1986), it's not a tremendous task to convert to numbers, but it is an odd choice on their part.

With the heat off in the greenhouse, what I am most interested in is how much difference there is in low temperatures inside vs. outside. The answer (so far) is 5 to 6 degrees. The average difference using the new thermometer has been 5.2 degrees, ranging from 12.6 to 0.1. When I was using National Weather Service data starting Dec. 1, the average was 5.5 degrees, ranging from 14.0 to -0.8. (For some reason, apparently it was colder inside than outside on Dec. 11.)

The difference in daytime highs is less useful and it depends greatly on whether the sun is shining. There was a 42.3 degree difference on Jan. 22, obviously a sunny day. The smallest difference was 2.1 degrees on Jan. 13, obviously a cloudy day. With the new thermometer, the average daytime difference has been 27.4 degrees, just slightly more than when I was using NWS data.

On sunny days in winter, the greenhouse will get warm enough for the automatic roof vents to open. If it gets above 80, as it has four times this month of January, the ventilation fan will come on. Interesting, but it's just trivia. The important takeaway is, on average, the greenhouse will cool down at night to 5 to 6 degrees above the outside temperature. Officially, the USDA Plant Hardiness Zone for Red Lodge is 5a. With this incremental protection from the cold and complete protection from the wind, inside the greenhouse it is at least Zone 6a. This is in line with what the interweb says about greenhouses. There are four plant varieties trying to stay alive in the greenhouse this winter: Garlic and allium in the soil, mum pots buried whole, and chive pots sitting on the ground. I think they are all doing fine. Sage is supposed to be hardy, but what is above ground in the planter right now looks dead. We'll see if it springs to life in a few months. Next year is the big test. I will be trying to overwinter strawberries in the planters and in baskets. Supposedly strawberries are hardy enough for Zone 5a, but surely 6a is better.

That's next winter. Before then, sometime in April, I will turn the heat back on and get ready for petunias, which are hardy to Zone 9.