Size the enclosure for the adult, not the baby
A bearded dragon grows fast, and a first home that fits the adult saves a second purchase and a stressful move within its first year. Aim for an enclosure around four feet long, two feet deep, and two feet tall for an adult, with front-opening doors that make cleaning easy and let you approach the dragon from the side rather than from above like a predator. A baby does fine in that space provided the basking platform, food bowl, and water are easy to find and there is plenty of cover to dash into. Line the floor with a solid, easy-clean surface such as textured tile or slate for a young dragon; a safe loose mix can come later, once the dragon is grown and hunting accurately.
Heat and the basking platform
A dragon's day runs on one hot spot. Build a flat basking platform — slate, a broad rock, or a sturdy tile stack — under the heat lamp, and aim for a surface temperature around 100 to 110 degrees for an adult, a little warmer for a baby, checked with an infrared gun on the surface itself rather than guessed from the air. The cool end should fall to the low eighties, so the dragon can shuttle between the two and choose its own temperature hour by hour. Run the lamp on a dimming thermostat where possible, keep night temperatures from dropping into the low sixties, and never use a heated rock: dragons sense heat poorly from below and can burn their bellies without moving away.
The UV tube is not optional
Bearded dragons are desert animals built for fierce sunlight, and their bones pay for weak UV. Fit a long UV tube — not a small compact bulb — mounted inside the enclosure or below any mesh, spanning the basking end so the dragon takes in UV while it basks, at the distance the tube's maker specifies for the strength chosen. A reflector behind the tube puts far more of its output into the enclosure instead of the room. Replace the tube on the maker's schedule even though it still lights up, because UV output fades long before the visible light does. Without this one piece of equipment, the calcium in the diet cannot be used properly, and the soft, bending bones of metabolic bone disease follow over time.
Furnishing: climb, hide, and hunt
Add a sturdy branch or cork round angled up toward the basking spot, a hide at the cool end big enough for the whole dragon, and a second shelter or shaded corner toward the warm end. Keep every furnishing stable — a dragon scrambles over everything in its home and will bring down anything loose onto itself. Put the salad bowl in the same cool-end spot every morning so the dragon learns where fresh greens appear, and keep a shallow water bowl even though many dragons drink rarely; some prefer droplets from rinsed greens, which is a fine daily habit to build instead.
The first fortnight's rhythm
Expect a new dragon to eat lightly and watch you warily for the first days; appetite follows security. Offer small insects dusted with calcium — several short feeds a day for a baby, one for an adult — alongside a daily chopped salad, and remove uneaten live insects rather than leaving them loose to nibble at the dragon overnight. Handle briefly and low to the ground once the dragon is eating well. A dragon that stays black-bearded, hides all day, and refuses food beyond the first week, in a setup whose temperatures you have verified, deserves a vet visit, because parasites are common in new youngsters. When a choice still feels unsettled in those first weeks, put a follow-up question to KinsLe's Kimmy; she answers using the KinsLe Answers library.