I know this is a very old thread, which I found while Googling about composting cardboard. But, it seems that no one has actually addressed the initial question, so I'll take a stab. What I have read is that corrugated cardboard is either made with no adhesive (the cellulose fibers stick to themselves) or with a biodegradable cornstarch glue. That's the cardboard itself - not any glossy labels or tape on it, or thick glues on the surface of the cardboard, of course. Some corrugated cardboard does have a thick plastic-y glue applied to the surface to hold it together into a box shape. I peel off labels and tape, remove any visible glue, and then shred or cut the cardboard into smaller pieces, and add it to my pile. It begins to break down almost immediately when enough moisture is present. I suspect that even the thick glues would not really be HARMFUL in compost - but I don't know if they would break down easily. I do what I can easily do to remove anything that isn't actually cardboard. If I were composting on a larger scale, I'm not sure I'd even remove stuff stuck on the cardboard. By way of an anecdote... I used to eat cardboard when I was little, with no ill effects. (Well, most would agree there were no ill effects. ;-))

Brandon7 and Great Plains 1, thank you for your postings. I revised my member profile to include the zone I am in, zone 6. I sent for the pads (they are from NV and my tortoise was not very interested in them, so I left them go except for the one I planted. I forgot to bring that one in and it is cold out (35 F) so I need to plant more. Getting to your comments, I feel terrible that it is a sickly, deformed pad, but you have it, it grew toward the only light it could get at the center of the box at the gap where the flaps met. I read that tortoises can handle the spines, but for our sake in handling them, burn them off or brush them off. These came with the spines already removed, and I would remove them regardless, since I don't want to take chances and hurt my tort. I believe it is a prickly pear cactus and the pads are maybe 10" x 6" x 1 cm. thanks for the help, a-planting I go!

All I care about really is that it holds up long enough for me to harvest tomatoes from the container. Where I live, no one will see it but me, it's very isolated there so looks aren't important. Also, it will recycle back into the soil. I see all kinds of posts and other websites promoting cardboard as weed barriers, walkways in gardens, etc. so decomposing cardboard into the soil must not be too bad of an idea. I plan on reinforcing the sides with heavy twine or wire crimped together and was going ot line the inside with plastic trash bags, maybe two of them, but I really wished I could just use the plastic on the outside of the boxes, it seems with a 5-1-1 mix or heavy composition of pine bark fines, the soil would drain well and not be too compacted or wet inside the box and it's going to be placed on carpet backing. Still undecided here about how much to get into this. Even if it disintegrates, it seems the potting mix would still hold together enough to be able to contain it and keep growing once the box falls apart.

Thanks all, I thought if they provided something useful to the soil/plants, like iron, after broken down, it might make sense to leave them. But as kimmq mentioned, they wouldn't provide the right kind of stuff anyway. I think they were steel, about 2", but not sure. And now that I think about iron too, cast iron type tub comes to mind... I guess I need to refresh my memory on chemistry a bit - probably no iron in those staples, but that's just an un-educated guess. So I had only put the piles of compost in the center, and was able to go around and easily pull out the staples. Covered in compost and mulch now, so it's all good, and I have a clearer mind that there won't be rusty staples out there for me, my pooch, or others to step on in the future because of me. But I do feel like a dufus... I had this big accumulation of cardboard boxes in my garage that just kept growing larger. Hated to put them in the recycling bin because I might need them to ship something in sometime. And I was initially buying newspaper, then postal shipping paper, then Home Depot rolls of construction paper(?) to put down before the compost and mulch. Then the light bulb went on, and it must be one of those low level solar lights in the yard that are too dim, and last too short a time :-)... Hmmm, why don't I use those boxes instead? For what I was spending on newspaper and construction paper and shipping paper, I can use the boxes instead, and if I need a box sometime, I've saved enough to splurge and buy one :-)