It does look like a very clean cut, but I live in a third floor apartment and the banana is not visible from the street, my neighbors love my garden, so I don't think anyone did it. There is no chance a dog came up here; pets are not allowed in the building, and it has a wide base so the pot couldn't have fallen over without a good push (but I'm not here 24 hours a day, so perhaps someone accidentally tipped it, but not that I am aware of). It does have a very thin band of dark colored tissue around the edge of the stem (about 1 or 2 mm's). The rest is clean and white. Now, you all said perhaps it will grow again... which part should I expect that to happen from? Should I replant the top? It's only been lightly covered in moist soil, but it may have dried out a bit. The root part has been left as-is, so I haven't covered the snapped part, just left it uncovered. I wasn't sure if it would rot if I covered it with soil. So should I plant the top or throw it out? Thanks for your replies!

Probably the single largest reason for the demise of cactus plants is overwatering. This can result in rot that is only apparent when the plant falls over. At this point, one has to consider the options. If the top is rotted but the roots are sound, it is a simple matter to cut the rot out. This wound has to be allowed to dry in a place with good air circulation or else the rot will continue until the whole thing turns to mush. Even a jagged cut with a pocket knife is better than allowing the rot to continue. If the plant is soft on the bottom, the roots are most likely also rotted and should be discarded. Cutting the top where the tissue is sound with a clean instrument is the surest way to start the rooting process. Sterilization of the knife is not always necessary, but the cleaner the instrument the less the chance of introducing any other pathogens to the cut surface. Make a nice flat cut where all of the tissue is sound, then allow to callous in an airy place until the face of the cut is dry. This can take several days to several weeks, depending on the plant and the conditions. After the callus forms, put the plant into well draining soil and do not water. It is not necessary to bury the plant, just good contact with the soil will suffice. If you water, you will have to wait for evaporation to take the water away because a plant with no roots takes up no water. While evaporation is working, so will rot, and the plant will most likely be set back even more. Keep the plant in bright, but not direct sunlight and wait. If it is spring and the plant has most of it's original tissue, roots can rapidly form and watering can be resumed in a month or two, usually closer to two. If, on the other hand, it is fall and most of the plant was rotted, root growth may not begin for several months and watering should not begin until evidence of root formation is evident. Evidence is when a gently rocking motion on the plant tells you roots have formed. If the plant was potted up recently, resist the urge to look for roots on a weekly basis. Monthly is usually often enough. Like many things with plants, it may seem counterintuitive to cut off as much as (or more than) 1/2 the plant and then expect something positive to result. You gotta have faith.

A picture would be helpful, but if it is rot you can save it by cutting off the rot, letting the wound dry and rerooting the remaining plant. It will take a while, but if you don't do anything it will spread and kill the whole plant. Or you can just root some of the pads. I just lost a plant that got the same treatment as all of my other 100+ plants. Sometimes it just happens, but in my case I think it was root mealies. If I would have taken the time to unpot it and look at it, it would be in better shape today. I had to cut 3/4s of it off and now I'm hoping for the best. When I finally took it out of the pot, it did not have one root. Sometimes there can be a slight cut or nick and the plant will get rot that way as well, so it's hard to say. Here's a link talking about rot: Causes of rot And here is a link to a thread that explains what to do in more detail Can my cactus be saved? Good luck with whatever you decide to do. It always hard to lose a plant.

You need to cut off all that rot ASAP, before it spreads. Cut up until you see completely green growth, no rot. You will have to let the cut dry for a week or so, before trying to root it. No water at all until you have roots. Christopher