Hi, @fieppief
Welcome to the forum.
If you leave a posting on that thread he was using, if he is still around he will see that someone has posted to it.
His profile shows he was last posted anything in 2021.
You can send him/her a personal message from that page and see what happens.
Measuring electrical currents in plants can be fascinating, especially plants that have triggered mechanical response.
Is there a current change when they do so, what response do you get to changes in environment etc.
A "Plant Spiker Box" sounds like something is missing in translation.
This link might help.
Try Google;
arduino measuring plant electrical currents
There are quite a few hits that may help.
Tom... 
