What should the temperature different between the canopy and the stem/roots area be if any?

What should the temperature different between the canopy and the stem/roots area be if any? I really could use some help. Let me know what your experience has been!

My canopy can be 28C amongst the leaves.

At my stem above the pot can be 20C.

My ambient temp is 23.2C.

Above the leaves you can get radiant heat from the lamp causing false readings with your gauges.

What temps are you experiencing?





J