Not browning on bottom

I seem to keep having this problem. My loafs seem of be fine on top. Good color and crunch. But the bottoms never seem to brown. 450 degrees for 30/35 minutes and one cup of steam to start. turn loaf once while cooking. Any suggestions how to get bottom browner?Also might like a bit more harder crust on top.

Thanks,

John, new guy baker and bread make