If you have a suitable, frost-free old vaulted cellar in which you have monitored the temperatures for at least one winter, you can, with the necessary precautions, also try brumating your tortoises there.
Which rooms are suitable?
Modern cellars, however, are not suitable: built to today’s insulation standards, they are too warm.
Brumation in lofts, garden sheds and barns is not advisable, as the required temperatures cannot be guaranteed there, and the tortoises are exposed to an alternating risk of freezing and of brumating too warm.
The right temperature
The temperature should remain permanently within the brumation range of 4.5 to 7 °C; temperatures that are too high are harmful to health. From 8 °C upwards, the metabolism starts up again, which can lead to intoxication and starvation. European tortoises should not be kept below 4 °C, as 3.7 °C has already proved fatal in Testudo hermanni (BONIN).
Brumation box and protection from predators
Choose the largest possible plastic box (for example the largest IKEA SAMLA box), fill it with soil and leaves, and place it on a table with oiled legs to protect it from predators and ground frost. The more soil and leaves it contains, the more constant the microclimate in the box remains.
Protection from predators is essential: a securely fastened mesh on top, and rat and mouse traps set all around. Some keepers also lay fine metal aviary mesh under the table to keep predators away.
The box is insulated with bubble wrap or aluminium-faced insulation. Insulating the box all round with Styrodur (extruded polystyrene) has also proved its worth.
Temperature monitoring
Monitoring the temperature at the tortoise by means of probes is just as essential in a vaulted cellar, and should be done with smart thermometers that have a temperature alarm. These tortoises are moved into the cellar in exactly the same way as into the refrigerator, namely in deep brumation. Like tortoises in refrigerator brumation, they are checked regularly, and in March they are returned, again in deep brumation, to the prepared cold frame for emergence.
Further reading: Gently into Brumation · Around the Tortoise Year · Moving Tortoises into the Refrigerator · Pit Brumation