Acclimating kratom to different humidity zone is very common and a most necessary practice to stop your plant from fully defoliating when the humidity is suddenly reduced. You may notice leaf curling upwards, this is the first symptom of humidity stress. For growers of plants like Mitragyna speciosa (A Hermaphrodite evergreen native to Southeast Asia) it is in fact necessary, as this type of plant is very sensitive to humidity stress.

[Quick instructions
SYMPTOM=leaf curl upwards and wilt when humidity is quickly reduced.
CURE=Increase humidity, then Reduce humidity by 10% every hour until upward curling stops. Increase humidity and restart process if curling continues.]

All plants exhale water vapor. When the humidity is very high the plant has less evaporative loss of water from it’s cellular tissue. This extra water builds up in these leaf tissues. The plant responds by moving water out of itself as fast as possible. When the humidity is reduced suddenly the plant doesn’t respond correctly from this unnatural change in humidity and will give off too much moisture causing the soft tissues of the leaf to curl upwards, wilt and defoliate if the plant is not put back into higher humidity immediately.

This is all due to the plant giving off it’s moisture too quickly. This stress is caused from moving the plant into lower natural humidity zones where you live if it was enclosed in a artificially created humidity zone like a sealed shipping package or a clear tub terrarium or tropical greenhouse.

To acclimate to a lower humidity.
First reduce the humidity to your tropical plant by allowing a small amount of ventilation of the higher humidity zone (Where the plant is) into the lower humidity zone (Where you want the plant to be) so that the humidity can slowly equalize to the lower zone at a rate of about 10% RH an hour, until the plant no longer shows upward leaf curl, or wilting. If the plant shows leaf curl increase the humidity and restart this process immediately until the upward curling no longer manifests itself.

Remember, if humidity isn’t increased the curling leafs will wilt and fall off which is completely unnecessary. This process can take a day or two, but it doesn’t require lights or heat but maintain 75-80F in low light if possible.

Mitragyna Speciosa can completely re-foliate in 30 days for larger girth plants of over 8mm stem girth. So even if you don’t acclimate these larger plants they will possibly not die from this type of stress.

(INFO FOR NERDS)
Plants with a main stem girth of 6-8mm had a mortality rate of 20% from not being acclimated properly.
Plants with a main stem girth of 4mm or less had a 70% mortality rate from not being acclimated correctly.
Fresh clones had about a 80% mortality rate from not being acclimated correctly.
Freshly sprouted seedlings had a almost 90% mortality rate from humidity stress related death.