Ook wrote:
I know I'm beating a dead dog here, but I find myself unclear about the
pros/cons of setting fence posts in dirt, gravel, or concrete. More
specifically, I'm undecided about which way to go. I need some input from
those who have done this. I'm mostly interested in what is strong and what
will last the longest. I don't want to have to dig them all out 10 years
from now and be stuck with these big concrete chunks.

Dirt: easiest to do, may not be the strongest. It rains a lot here, 9 months
out of the year, so I'm concerned about the constant contact with wet soil.

Gravel. Some recently suggested. Cheaper and easier then concrete, gravel
drains water from post. Stronger then just dirt, post may last longer.
Gravel drains water from post.

Concrete. More work. Strongest. Post in contact with concrete may still rot
out in 10 years. Difficult to replace.

Lots of great ideas here, but here's a couple more. In the countryside
around here we have the occasional redwood fence posts with barbed
wire. Redwood lasts a very long time, but the reason they still stand
is due not to concrete but shale that's driven alongside the footer.
When I reconstructed a fence along part of our property, I pulled out a
couple misplaced treated 4x4 posts, and the part that was in the ground
was as good as new. 40%copper pressure treated posts last a long time,
and look better than steel or vinyl posts, in my opinion. I agree that
concrete is so permanent to be a nuisance around the property. But, it
does hold posts well and the post won't rot if the very bottom isn't
sitting in a bucket of water soaked concrete. I didn't want to spend
too much money on concrete, so I combined the pounding of shale and
other flat rocks at the foot to make the post tight, and then at the
top of the whole, I filled in a bit of concrete and mounded it a little
so that dripping rain drains away from the post. Posts can support
each other, so I used galvanized metal brackets to hold the cross
supports between each pair of posts (set 8 feet apart), 2x4s set on
edge, rather than flat, so that I wouldn't have the saggy look so
common on fences in my area. These cross supports were 10%copper
pressure treated posts, cheap and available at Home Depot, so I used 3
cross supports, rather than two. The top plate connecting across posts
were 20ft long 2x6 redwood, and the visible lumber used was carefully
sorted for heartwood 7/8"x5 redwood planks found also at Home Depot. I
cut off the dog ears and put the edges under the overhang of the top
plate. I drilled and used screws, not nails, which takes a little
longer to put up, but results in fewer split boards and an overall
stronger fence. Along the bottom at dirt level, I linked posts with
1x12 redwood as a kickplate, filling whatever holes with spare rocks to
keep the dogs in the yard. Later, I decided that the southern exposure
of the fence would look good with grape vines, but I wanted to make
sure the fence would suffer from the extra weight, so I drove 2x2 grape
stakes every 4 feet, and anchored with screws to the existing fence at
the post, and half-way between, and then put half-way up and just under
the top plate, horizontal 2x2s to tie across and create an easy access
trellis to tie on the vines, which are spaced every 4'. Ultimately,
because the vines are away from the wood, and well pruned of foilage
and excess wood in winter, they will actually provide additional wind
resistence for the fence by their root strength. In summer, the
foliage shades the wood, reducing exposure to the harmful effects of UV
rays that will over many years will split up even good redwood
planking. Anyway, this is the story of a 100' section of fencing on my
property. Incidentally, I like the grey color of weathered redwood, so
I wouldn't bother to stain or paint the fence. I don't want the extra
maintenance.