KitCMC I think there are a few factors to consider regarding hardening off. 1) How intense(light, heat, humidity) are the growing conditions of the cuttings? 2) What are the outside conditions(overcast, sunny, hot, humid, windy)? Whenever there is a drastic change in light intensity, humidity, air circulation, ambient air temperature, soil temperature, etc., most plants will not like the drastic changes. Another consideration is the type of growth on the cutting. Are the leaves leathery and dark green, or light green and delicate?
With so many factors, it's difficult to have only one answer to your question. Filtered sunlight is usually preferred when hardening off, but sometimes that's not possible. Morning sun in the cool of the day for a few hours is a safe beginning place for adjusting to outdoors. If possible, don't leave them unattended, but check on them regularly the first few days they're outside. Gradually move them into more hours of sunlight, building up to leaving them in full all day sunlight. Monitor soil moisture, and mist them if the weather is hot, even after they seem hardened off.
