I've learned never to plant anywhere close to streams or gullies unless you want your box to be gone after the next big flash flood event. I've also lost boxes to controlled burns, but I'm not sure I could have anticipated that coming... :)

I have been there and done most of what you listed. I just recently pulled a box at a local park due to location and lack of finders not rehiding as well or better than they found it. I checked on the box twice and both times it was just sitting out in the open for all to see. I was surprised it lasted as long as it did. I knew when I planted it that it was a risky spot!! I have also done the late fall or winter plant only to find in the spring time that the box or boxes are now overgrown and not accessible. The ones that are the most disappointing are the ones I was sure were in a great spot and ended up gone :(

I just had to move a box due to poison ivy. It really was not my fault. It was there 3 years before poison ivy invaded. I was quite surprised, when I went to do maintenence last weekend.

I had to scrub shoes, while wearing gloves, launder socks, scrub legs, and then I read that gloves have to be worn once more, for scrubbing the laundry basket. Just did that now. Jeepers.

That same series had a giant tree with a hole, which was my first plant ever. Apparently, that was a notable tree that others went a-hunting inside. That box disappeared after 2 years.

One year my daughter and I bought a live Christmas tree. We cared for it carefully. After Christmas we took out to the coastal forests of the west coast. We found a sunny spot among the redwoods and lovingly planted it. Over the next several years we hiked out to check on it... it was growing beautifully.

Then came the day we went to visit our little tree that could and found that it had been smashed flat by a fallen redwood. What are the chances? ☹️

My first letter box was on a river bank.

I second the "Hen" - gullies and watersheds that don't look like gullies and watersheds until a hard rain happens through. I have lost at least 3 that way, all in the same park.

Ah, the 'tree with a hole'... and then the hole grows closed and the box can't be extricated.

Not really a planting mistake but - I have a box in Texas that was on the far side of a small clearing beside a trail thru a country park. A year or two later I start getting reports that it is getting hard to get to the box as cactus is encroaching on the clearing. The last report is that the clearing is completely filled with cactus now. I'll be relocating that box ASAP.

and then the hole grows closed and the box can't be extricated

I would never have expected that!

I planted in a hole at the bottom of a small tree at the edge of a cemetery. I had a strong wire attached to the box so it held the box up inside of the tree. The wire, even though it was black, must have been too visible because it kept disappearing. I had re-carved and re-planted once, but didn't want to carve it for a third time so I gave up. I had permission to plant in this City owned cemetary, but I don't think the grounds crew was ever told. I suspect they are the ones who kept removing it.
I've had a bonus box disappear too. When I replanted, I made sure to include instructions to leave it there! It was weird, because they left the clue in the initial box, but kept the bonus box (or it was muggled, you never know!)

Ideally, I should plant it so it is hard for it to be found accidentally, but still provide a clue that allows it to be found intentionally!

The trick is to make the clue so mind-numbingly impossible that no one will ever notice it went missing. Saves you on the blizzard of hate mails that say you did this wrong and you did that wrong even tho you did all the work for the community at large's amusement.

More practically, the cardinal rule is "zero chance of accidental discovery". What that means, at least to me, is under a rock about 10-20 feet off trail. Find a moderate sized rock, pull it up, dig out a boxed sized cavity below it, disperse the dirt, put down the box, put the rock back exactly as it was.

DO NOT EAT before planting or finding letterboxes. Animals are smarter than you, and off goes the box when they think it smells like trail mix or a PBJ sandwich.

OK, some locations don't have rocks, and even for those that do, this suggestion represents an ideal scenario as opposed to where the clue says the box should be (you do write the clue beforehand, I hope :)). You get the gist. Don't hide it under a pile of sticks or a rotted log. We've all done it, and we all know it doesn't work. If not practical, take the principle of my suggestion. Good luck.

I would never have expected that!

Neither did I! :D But I was able to get the box out by removing the lid - one-handed - and then squeezing the lid, the box, the contents out one by one. Definitely a lesson learned!

Hey, I planted a box on a beach, and it was found on an island in the Gulf of Mexico. I had tied it down with string, but string doesn't hold up well.

Ah, the 'tree with a hole'... and then the hole grows closed and the box can't be extricated.

I have cut at least two out of such trees. No, I didn't cut the tree down, I just widened the hole until the box could be retrieved.

under a rock about 10-20 feet off trail.

A tooth shaped rock?

I usually have the opposite. The hole got bigger and bigger, and rotted. And someone must have fished the box out, at some point. Or, sometimes the box falls in, when the hole grows bigger and bigger.

This is embarrassing, but I planted one at my college campus. No body on campus really knows what letterboxing is, and this was before I had discovered Atlasquest. In the classes where the teacher asked what we did over the weekend, I said I planted a letterbox on campus. Naturally no one knows what this is so I explain it to them. The teacher wuss ask for the clues and I would give them to her, and she would put it in our "class discussion forum" (which is basically a social chat for the classes eyes only.)

A week later, I went to check on the box, and the stamps had been torn to pieces, and a lot of profanity was drawn into the logbook I got for my first box. I immediately took the box away, changed the clues/hiding spot, and redid the entire box.

I will never push people into something unless I trust them. As a freshman, I thought it would be a great way to make friends and create something to have in common with them. My, oh my, how that turned out.

Yes, but imagine the cool find that archeologists or construction workers are going to find when they go to look at the tree!!!

I thought it would be a great way to make friends and create something to have in common with them

I've been trying to pull my friends into letterboxing and I have had friends try it, but no one seems to like it enough to devote additional time to it.

I thought it would be a great way to make friends and create something to have in common with them. My, oh my, how that turned out.

It's a rare DNA abnormality that makes someone charmed by letterboxing.

A week later, I went to check on the box, and the stamps had been torn to pieces, and a lot of profanity was drawn into the logbook I got for my first box. I immediately took the box away, changed the clues/hiding spot, and redid the entire box.

This happens sometimes with geocaches too. Don't necessarily blame those in your class (directly). They could have all been okay, but maybe careless when they found it. Then someone else went and did this. They are called muggles.

And you'd think that all people at a college campus would act in a mature manner and not do this. Nevertheless, there are jerks everywhere.

Re-hiding it was a wise decision, preferably away from well traveled areas.

I lost two of my early boxes to flooding in spots that I should have known would flood. To compensate, I began planting in higher elevation spots. When rehabbing a broken foot (not from letterboxing), I realized some of those boxes are a PITA to get to. So now I try to always plant somewhere dry but not too high. I prefer rocky spots because they are easier to anchor boxes, but there is the snake factor to consider.

I lost two of my early boxes to flooding in spots that I should have known would flood.

Here in Florida, that describes a high percentage of the better hiding spots! Public parks are often in low-lying or flood-prone areas, possibly as a means of preventing stupid people from building houses in those locations. Whatever, avoiding flood-prone locations would mean forgoing many if not most of our public areas.

My solution is to go ahead and plant, but to tie the box down so it cannot float away. I use stout string -- but it should be noted that it doesn't last forever, the string eventually rots away and needs to be replaced every few years if you hope to actually have a box after a flood or hurricane.

I've also been known to use a light chain, although these can rust away over time. You can purchase stainless steel or plastic chain, but I was using stuff I had laying around rather than spending money.

One nice thing about tying a box down: It also seems to help the box stay put even if there isn't a flood. I guess when someone is picking up litter, finding the item is tied down with a string may make them think twice about whether it is something that should be tossed.

Just recently I found a geocache that was tied down. It was not in a flood-prone area, but it was in a spot where a grounds crew might toss it. The geocacher went the extra mile, though, and tied down his cache with HEAVY chain and a padlock! You coulda towed your car with that chain!

How are you chaining boxes? What are you tieing them to? Around a tree trunk?

One of the first letterboxes that we found (and that tempted us into the hobby) was a letterbox hybrid geocache. It was an ammo box chained to a tree. The stamp had a wood backing and was attached via wire and screws to the inside of the ammo box. Considering it was subjected to a constant flow of cachers it was in great shape.

I realized some of those boxes are a PITA to get to.

Nothing wrong with that! Make 'em work for it!

One of mine that was in a park went missing recently and the last person who looked for it said it appeared to have been burned! I seriously wondered how anyone would have just found it in the first place (it was well hidden under a boulder) and then why burn it? Some people ...

Around a tree trunk would work if it doesn't make the hide too obvious. Sometimes around the trunk of a very small tree works well. Alternatively, I'll loop it around just one root of a larger tree. In any case, such a loop needs to be deliberately very loose so as not to impact the tree's growth. Sometimes I include a ring and a clip so the finder can unhook the box and carry it somewhere to stamp in, but that's not really necessary as the finder can simply open the box and take the contents off somewhere while leaving the entire container at the hiding spot.

Most of my hides are screw-top jars, so I'll tie a string or wire around the neck of the jar. A few years back I developed a scheme for tying a string across the lid of a Lock N Lock to form an X pattern, with a key ring or some other sort of ring at the cross of the X. Then a carabiner or other form of clip tied to a tree with a cord or chain can be used to fasten it down.

Other ideas include the use of a mesh bag. Tie the mesh bag down with a string, then put the container inside the bag.

I seriously wondered how anyone would have just found it in the first place (it was well hidden under a boulder)...

I hid a box under the edge of a boulder once, and when I say boulder, I mean this rock was ten feet across and five feet high. And this was in Florida, making the existence of any rock at all, let alone a boulder, a rare thing indeed. I got a few very confusing not-found reports, so I went to check on it -- and discovered that someone had busted up that boulder into hundreds of rocks less than a foot each, creating a little rock field. No box to be found. Aaaaargh! Sometimes you just can't win for losin'.

And this was in Florida, making the existence of any rock at all [...] a rare thing indeed.

You folks have the Coral Castle. What more could you want?

(he says as his best and most futile work was based on that abject monument to futility)