I am looking for a way to stablize 4x4 posts in the ground without using concrete. Specifically, what I need are holes in the ground into which I can place 8' 4x4 posts into so that I can hang banners between them secured with bungie(?) cords. The old holes were just dug into the ground and we would put the "sign posts" into them and string the banners as needed. When the signs are no longer needed, we untie them and take the posts out of the holes and place "plugs" (small 4x4 posts at ground level) so we can mow over them without hitting anything. The holes have obviously gotten larger over time and I need to fix this situation. We do not want to have premanent poles in the ground - only put them in when we need to hang a sign. Is there anything I can use as a sleeve that I can place in the ground to keep the holes open so that I can put the 4x4's in them when we need to? I thought I could put this "sleeve" into the holes and backfill with blue chip if that would work. If I have to, I can put these "sleeves" in and backfill with concrete. I just need something that will hold up over time. Or do I just have to make concrete holes for the 4x4's? If so, what do I use as a form and when and how do I get it out?

Maybe switch to pipes. My flag pole at home stands in a pipe. Trick is to find the right fit.

That would work. I would just have to drill holes into the pipes so I could secure the bungies somehow so the banners do not slide down the poles. Thanks for the idea

Go to Lowe's and look into the pvc piping. My thoughts would be to concrete those pipes in the ground, but low enough to where you can mow over them, id say make them around 2ft deep, as far as setting the post in the pipes, if there a little loose then use a shim on all 4 sides of the post. After your done using it, pull out the shims and pull up the post.

Like the idea for using pvc in concrete to hold the posts as well. Thanks - that's why I love this site - such great ideas!

You could even buy a piece of sonotube if you are going to concrete around it. Normally you put concrete inside a sonotube but it works well on the outside too.

We have a backyard clothesline setup. There is a pipe in the ground, probably in concrete, that is at or just below turf level. Into this pipe fits the "umbrella" type clothesline pipe... just slips in to the ground pipe. Then you can expand the arms of the apparatus when you want to hang clothes out. Since we don't use it much I generally don't have the clothesline setup, since it isn't the prettiest addition to our yard, even if it is entirely private.

So most of the time the ground pipe is "empty" and I have it covered with a square paver brick that doesn't look too out of place.

Trick I guess is finding a pipe that snugly fits into the ground pipe. Bet its not too tough. At least another option.

Thanks to everyone who responded. Actually ended up using the pvc idea. Found that they make 4x4 plastic sleeves that normally fit over railing posts - sunk them in a little over 2 feet deep and concreted around them about half away up the hole. I plan to fill in the rest of the way with the extra dirt we took out and then plug them with 4x4's cut to the depth of the hole and put and eye screw in them so I can pull them out. Everything will be low enough to be able to mow over them. Once again, I love this site!

I actually did this with a fence post for my privacy fence. We sunk a PVC pipe in the ground and concreted around it. Then we lag bolted the 8 ft fence panel to it. Now, I always have a 5 foot gate, but in less than five minutes, I can remove the lag bolts, pull the 4x4 out, and have a 13 foot wide gate. I love it.