It all depends on the beardie itself. Mine just started brumating two weeks ago, and he's gotten to be a pro at it. He just decides for himself when he wants to settle down and nothing short of an atomic bomb is gonna move him.
It is important to lower the temps somewhat in your tank as well as reduce the amount of "sunlight hours" he/she's getting per day, so you end up creating a seasonal turn for him/her. Then you can offer occasional greens and/or water to keep them hydrated, but lots of times they won't even bother with it. It's more important to at least keep them handy if they decide they're hungry or thirsty and you're not there. I usually turn my daylight timer back to 8 hours and the temp down to 80-85 deg. in the day (more around room temp), and no less than 65-70 deg. at night.

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Dl