I have read that dormant hardwood cutting propagation is helped by placing hardwood cutting in propagating medium in a pot on top of a heating mate. I have not read any opposition to this view. However I have also read that heat is "not required" any more after callus is formed on the basal end of the hardwood cutting; but 'not required' is different from knowing if the bottom heat will still provide some benefit or it is detrimental rather than being helpful to keep the rooting pot on heat mate after callus or root initials or roots itself. I will appreciate comments if someone knows the botanical aspect of this issue or just have personal observations as to when the bottom heat can be removed for better results, that is after callus is formed, or after root initials are formed, or after roots have started? If it is true that once roots start on hardwood cuttings they grow better in cooler temperatures then I can place the rooted cuttings at room temperature (with good RH) and use the heat mate for starting new cuttings.