I would adjust and lessen a bit the winter watering Ken, even if you have it in a solarium. But the younger ones does need to be kept moist, but not too frequent water. The roots below soil level can further fatten up so it does not help watering them too much, they might rot.
One time I decided I want to know what the roots look like below on one of my younger Adeniums. It was dormant at that time anyways, so I dug it up to look..roots look like ginger, so it does tell me, be careful in watering.
