PAR

1 lux = 0.0185 umol m^-2 s^-1

The units of PPF are umol m^-2 s^-1 (micromoles of photons per meter squared per second) or mol m^-2 d^-1.   The table below provides a guideline for light levels for certain plants.

http://www.apogeeinstruments.com/conv_lux.htm