From juvenile to adult terrarium: when and how to upgrade?
Published by Planète Pets · managing editor: Clément Lacaille · how our guides are written
The move to the adult terrarium should be planned ahead: once the reptile reaches 60 to 70 % of its final size — around 8 to 12 months for a bearded dragon, 12 to 18 months for a leopard gecko or a corn snake — the grow-out enclosure becomes too small. Budget 200 to 450 € for the upgrade, with part of the juvenile kit remaining reusable.
Contents · 5 sections
How do you know a terrarium has become too small?
The animal rubs its snout against the glass, paces the walls relentlessly, or can no longer stretch out to its full length; the thermal gradient also collapses, since the cool zone barely exists in a small heated volume. Do not delay: a cramped enclosure breeds chronic stress and inactivity, with obesity to follow in greedy species.
Which equipment to rebuy and which to keep?
- To rebuy: the terrarium itself (see our glass or OSB comparison), a more powerful heater sized for the volume, and often a longer UVB fixture covering two thirds of the enclosure;
- To keep: thermostat, probes, timers, bowls, feeding tongs;
- To add: larger hides, branches rated for the adult's weight;
- To check: the stand — a furnished adult glass enclosure easily weighs 80 to 120 kg.
How do you manage the transition without stressing the animal?
Run the new enclosure empty for several days to settle the temperatures, then transfer a few items steeped in familiar scents: the main hide, some of the clean substrate, branches. Expect a cautious week — nocturnal exploring, reduced appetite — that is normal. Furnish densely: a big bare volume unsettles more than it liberates, especially after a rocky start.
Can you skip the juvenile enclosure altogether?
Often, yes: a juvenile does very well in a densely furnished adult terrarium, which saves 100 to 200 € on an intermediate enclosure. The exceptions: very small insectivorous juveniles, whose meals need monitoring, and nervous species that feel safer in a reduced volume. Both strategies are defensible — the per-species guides in our reptile habitat section will help you decide.
Frequently asked questions
What should you do with the old terrarium?
Keep it as a quarantine or hospital enclosure — a genuine asset — or sell it on: a clean grow-out enclosure sells fast at 40 to 80 €.
Do you need more heating power in the big enclosure?
Almost always: a doubled volume calls for a stronger spot or a second heat source to recreate the gradient. The existing thermostat remains valid as long as the connected wattage stays under its limit.
Does the upgrade change feeding needs?
Indirectly: an animal that moves more in a bigger enclosure burns more, but it is mostly maturity that reshapes the diet — fewer prey items, more vegetables for a bearded dragon, for instance.
An accessory from our shop for this use: Stick-on digital thermometer for aquarium and terrarium glass (€18.90) · the whole shop
This guide is part of Planète Pets’s Reptiles universe. Our advice is general in nature: for any health concern, your veterinarian remains the only reference.
