A significant concern anytime you put wood on or in the ground is rot because no matter how hard wood is, it is an organic material that will break down over time. As such, you should do everything in your power to care for the wood and prevent rot. Here are a few different materials to set your fence post so that you can slow the rotting process and keep your structures in place for longer periods.
The first thing that most people think of when they consider grounding posts into the ground is concrete, and for good reason. Nothing can hold a structure in place longer and stronger than concrete. But there are flaws with the design of concrete. As an organic material, wood needs to breathe, and when covered in concrete, it cannot do that, so it will slowly break down over time. This is especially true if the wood gets wet and does not dry quickly.
Another popular method of grounding posts is the use of metal footing. This is a very quick, clean, and easy process that involves drilling holes into whatever the footing will be secured to. Then, lag bots or large nails like fencing u-nails are used to secure the base in place and provide additional grip. The use of screws is also advised if you choose this method, as they have high grip strength.
Gravel or Loose Rock
Believe it or not, the old tried and true method of using gravel is still a great option for keeping your posts in place. This method has been used for many years and still holds up. Gravel has a way of packing very tightly, and it grips exceptionally well. If you pour a dense amount around your post and pack it down, it should hold the post in place just fine.
With so many different materials to set your fence post to choose from, you should have no issue selecting one for your purposes. Just consider what the structure will be exposed to over a long period of time to determine which option will work best.