Opinions re LaCrosse temp allert system

[iamppdoc]

We have a small greenhouse, attached to our house, in western North Carolina. We can be below freezing for 2 to 10 weeks per year. Does anyone have any experience or opinions about the LaCross temperature wireless alert system? They say the sensing unit will broadcast to the receiving unit, which is plugged into your internet router, up to 200' away. You can then monitor the temp and humidity from your smart phone. For a small fee, they will send you text messages if your exceed your temp limits. his would seem to be an excellent idea, especially if you were out of town and had a problem.
Thanks for your thoughts.

[estación seca]

I haven't used this unit, but in the worst weather (ice storm) your electricity might go out as well. The serious growers I know walk out to their greenhouse several times each cold night, and they have backup heaters that don't require electricity.