I live on the side of a mountain (hill). Needless to say it's quite rocky. I really have a big need for post holes. Is a 3pt. tractor post hole digger out of the question in my circumstance?
Kubota B8200, then a Kubota L3130 HST, now a Kubota L3400 HST
When you say rocky, do you mean large buried boulders, or simply lots of stone, baseball size or smaller? If you can safely operate the tractor on your hillsides, you can likely do the same with an auger. I have found that tree roots, 6" in dia. and BIG rocks cause trouble.
Good luck.
You might need to use a hydraulic "down" cylinder to apply downward pressure to help that auger bore holes for you. Or, get a hydraulic auger that attaches to your front end loader bucket and use those cylinders to apply down pressure. B.
Careful augers can drive themselves in like a wood screw, the only way to withdraw them is to unscrew them. In our area (canadian shield) rock can make augers almost useless. Our soil on average would be 40-60% rock and the balance being clay, the rocks range from the size of your fist to a small car. However it's the stuff the size of a basketball to a bathtub in a pile that an auger will screw itself into. The only way we have rescued a few augers is to put a 4' pipe wrench with a length of pipe and some strong backs. We have cut off a couple too. Have a good bar handy you may need to remove some by hand. Good luck, slow and steady will win the race.
Kubota B8200, then a Kubota L3130 HST, now a Kubota L3400 HST
I forgot to add some info another set of posters once shared with us here on TbN: sharp cutters on your PHD make a ton of difference in how easily they cut holes. And, I have had to use my 30" pipe wrench with a cheater pipe to extract my auger- it ain't fun.
Thick tree roots can also sometimes snag an auger bit. I'm pretty happy with the effectiveness and versatility of my hydraulic auger (I like the ability to push down and reverse)...though I'm planning on installing a back-up or trailer hitch camera on the FEL arms so I can more accurately position the auger tip.