Temperature Control?

I’m looking to controller the temp in a small plastic ‘green house’ in my basement. Would it be possible to control a 120v GE plug with a heater plugged into it with SmartThings and some time of temperature monitor? If so, what type of hardware would be recommended?

In theory, yes. I did the same with a heater in my office using a smart plug and ecobee room sensor. Any device that reports temperature should work. But depending on the value of what is in your green house, you may not want to use SmartThings for this application. It relies on the internet, so if your internet is down, or the SmartThings cloud is down, the heater may not get turned on or off and harm whatever is in the green house.

Depends how simple you want it and what other stuff you have.
If you have nothing else, the simplest and cheapest way would be to use a Sonoff TH10 or TH16 depending on the power of your heater. 10A or 16A. Buy one with the temp sensor and thats all you’ll need except for some flex to wire it up. Use the ewelink app to control and set your auto on/off temps and your done.

You can get the from amazon, ebay, banggood, aliexpress and prices vary quite a lot so shop around depends how quick you want it.

This is strictly outside of smartthings, and currently the temp cant be read in smartthings but the condition of the switch can so you’ll know if its on or off.

Heres one such link.