Botanical beads are made from natural organic (as in plants, not necessarily "certified organic" or even "unsprayed") materials and as such are biodegradable. This will happen in most climates unless you prevent it.
That said, from my own experience, the worst experience I have had was that Job's tears stored in our storage locker were smelling a bit musty after a year. They were OK after I aired them out, and I never stored them there again.
This morning I got a phone call, a lady right here on on the Big Island made a necklace from mgambo/weleweka/velvet seeds and noticed some sand like substance. I told her to stick it in the freezer (as the freezing temperatures will kill any critters inside the beads) and my husband commented after I told him what the phone call was about "termites". Storing the beads in the freezer for a while will kill termites too. (I did not get whether she bought the beads from me or not)
Another thing I am aware of because a co-worker showed them to me (I actually have them here) is mold on weleweka seeds. I don't know how wet her earrings got, but she aired them out, here in Hilo, and that didn't prevent the mold. If you live in a humid/wet (and warm, even if only at the time, think even northern states/provinces/countries in the summer and in the southern hemisphere in what is winter here) climate and your botanical beads get wet you may want to dry them in the fridge or freezer.
Botanical beads may look like beach jewelry and if you only want to wear them while you're here/there that's fine, but they are not made to get wet. They may germinate if you get them wet enough for long enough if they're made from seeds. After all,l that's what they are.