You'll need a photosynthetically active radiation (PAR) meter or quantum sensor to read the amount of light at your plant's location to figure out the DLI or Daily Light Integral, the amount of light each plant requires each day.
These can be found on Amazon below:
You'll need two tools/meters to check your VPD:
A hygrometer and a laser thermometer.
You'll need readings from these two instruments so Hortus can calculate the vapor Pressure Deficit (VPD).
The hygrometer measures the room's temperature and relative humidity.
The laser thermometer measures the surface temperature of leaves.
These can be found on Amazon below:
Hortus can use daily readings from a wood or hay moisture meter to provide guidance if you're growing plants you want to dry after harvest.
These can be found on Amazon below: