The rule of thumb is to set the fence posts one third (1/3) of the fence height they will support. So a six (6) foot high fence should be buried two (2) feet deep. However, central Texas has a large variety of ground densities ranging from loose soil with a little clay to solid rock. Depending on the soil type and density, hole depth may range from six (6) inches in solid rock to two and one half (2-1/2) feet or more in clay or loose soil. Our GOAL is to bury posts one third (1/3) of the fence height.