Reptile & Amphibian Forums

I have two box turtles I got this year. They are long term captives and have been hibernated outside in the past. I live in Northern Virginia outside of Washington, DC. I have an outdoor pen 15 feet by 20 feet. How far down do I need to go to loosen up the soil for hibernation? It is clay after about six inches deep. I plan on mixing leaf mulch and hardwood mulch with the soil.

I answered you e-mail, so check that...I'm a little farther south but pretty much the same climate zone. We erred on the side of caution and dug down below the frost line, to a depth of two feet.
Mixing leaves in with the soil is a great idea: we also mixed in peat moss rather than mulch, coz mulches can contain fairly large chunks of wood or bark and we didn't want any obstacles, since one of our turtles is a young amputee.
You may need to amend with equal parts organic matter/soil, if the clay is that really heavy stuff.
We'll be creating more hibernacula this week and probably won't dig as deep, but compensate by piling higher (leaf litter etc.)
Make sure you dig in a higher spot, so you don't have water filling the hole up like a bathtub.

Steph's advice is sound. I would add a high pile of mulch on top of the loosened/amended soil. This serves two purposes, 1, to shed water off away from the hole beneath and spread out the moisture to prevent excess, and 2, extra insulation. I'm far enough south that mine just go into the pile and don't bother digging down into the ground beneath it, even though they could.