@sharq
Here’s an update on my post far above.
The two scions I grafted are still looking healthy. Our daytime temperatures have been in the 60’s F and pre-dawn lows in the low 40’s. One of them is pushing leaf buds, but real test will be their status next summer.
The cuttings I’m attempting to root are indoors with nearby air temperatures ranging from 64° to 78°. Underneath the tray and towel (pictured above) is a Sunlight Supply 9" x 20" seedling heat mat. It is plugged into a timer that is on from 6am to 6pm.
Water is added to the rooting containers based on weight (thank you @fruitnut). I weigh the container tray after each watering has drained for an hour, and then periodically until significant weight loss is noticed but without totally drying the containers. Then the watering cycle repeats.
By the way, I cut a row off the 4 x 5 Stuewe mini treepot tray so it would fit in the Sunlight Supply super thick 10 x 20 drainage tray.