It ensures that adequate calcium is available at all times. It is our experience that 'Vionate', another regularly used supplement, whilst adequate for routine use with adults, is not sufficiently high in calcium to guarantee good bone development in hatchlings. Certainly, in spring, summer and on warm autumn days they will do far better outside than if confined under artificial conditions in a vivarium. A strong covering of wire mesh will ensure adequate protection however. A natural, earthen base is best and will allow the juveniles to express their natural desire to dig and burrow.
Some plant cover is also essential.
Such an outside terrarium is infinitely better than even the most carefully constructed of interior vivariums. Compare the behaviour patterns of juveniles housed in this way with those kept permanently indoors under artificial conditions. Obviously, in very poor weather juveniles will require some indoor retreat. But try to keep this as light and well ventilated as possible. An open-topped 'pen' arrangement is definitely recommended over enclosed vivariums.