HI,

I recently built a shed for my fig tree and found a great thermometer that is wireless ( upto 150 feet )  with which to monitor the daily temp from the comfort of my kitchen.
This device is only $30 in Canada so likely cheaper in the US and readily available at Walmart .
It records the high & low temps of each day and keeps a log for 5 years. It also gives you an indoor temp reading of the location in which the display is located.
And it is very accurate . I have been comparing its readings with a calibrated temperature sensor I use for work and they are within 1 degree F.
You could put the transmitter onto your tree and wrap it if you like .
I originally heard of this device on a northern gardening forum .

.........John

Thanks John for the useful information.
I can use such thermometer to record temperature inside the cold garage for turning on an extra heater when it really gets cold.

Ottawan i beleive they are 18 dollars at home depot or lowes..

I have one. They work. But range is limited. 80ish feet to my greenhouse is too far for mine, but it lets me see outside temp without going outside, and it can be a way from the house, (and not affected by heat radiating from the house or captured under the eave) unlike the more traditional indoor/outdoor models. I have a model with two outdoor thermometers, and I find that they are usually 3-4 degrees different from each other, so be aware that they are probably not dead accurate.

Great tip.  Here is the one that I have:

http://www.amazon.com/Oregon-Scientific-RMS300-Datalogging-Forecaster/dp/B001350E84

You can add up to 4 remote sensors in case you have more locations to check.  Works very well and getting ready to get a sensor for my garage.

Great input guys .

I definitely like the the multiple sensors option . I bought the cheaper single sensor unit thinking, how reliable can these units be ?
But I have been using it for a couple months now first in my small greenhouse and now in the fig shed and I find it to work fine. Next year I will have to upgrade to the multi sensor like Dennis & Pitangadiego .
The humidity feature sounds intersesting but from my experience with humidity sensors ( I service & calibrate temperature and humidity test chambers ) they are not very accurate. Thier accuracy tends to drift over time even on the expensive units. However temperature sensors usually are very reliable. Now the wireless part well we will see.

 John