Can I just dig a hole around the post and fill it with postcrete?

if it isn;t already set in concrete and rotting through at the join then yes.

Personally, I’d put a concrete repair spur on the existing post prior to concreting it in – it’ll save a lot of effort later on.

Postcrete is great stuff.

If you are gonna dig then put a new post in, assuming it is wood.

If its concrete then also check integrity before adding postcrete.

Didn’t know about the spur. Will get one.
Thanks.

Posts set in concrete always rot where the water rests on the top of the concrete.

I’ve spent the last few years putting spurs into the posts down the side of my garden as and when they snap in a strong wind. Takes about 2 hours per post to dig the concrete out and fit a spur to repair them. If I ever fitted a fence myself I’d put the spur in to start with. they’re about £15 each at Wickes.

Posts set in concrete always rot where the water rests on the top of the concrete.

If you leave a depression round the post, easy enough to form concrete so the water runs away.

Had alot of fence posts rot untill i was told to put gravel in the bottom of the hole so the water can drain out the post.Better with a spur though