The thickest walnut tree in Slovenia grows next to the church in Kočevska Reka. It is more than 400 years old and reaches 434 centimeters in height. The Kočevje area has a rather harsh climate, which is not favorable for walnut tree growth. The fact that the thickest walnut tree grows right here, however, is consistent with the finding that it is often in the marginal conditions and at the edge of their range that trees reach their maximum dimensions.