There's lots on containing bamboo on-line. I'm sure that will give you some ideas that will be applicable.

FataMorgana

Here is a link that might be useful: Bamboo Containment

FataMorgana- Thank you for the link. I've been on the cottage forum and some people were saying lemon balm can spread quite a bit. Have you had any trouble with that, or do you just give it a lot of room?

Lemon balm self-seeds. No barriers or pots stop that. You can deadhead but I'm never bothered by the "volunteers" very much. I dig them up and give them away or harvest them out of existence where I don't want them.

Lemon balm plants can get sizable but regular clipping & harvesting can keep them shapely and reasonable garden neighbors.

FataMorgana

Thank you. I'm thinking of putting the lemon balm in an area where it can spread all it wants, much like the spearmint. That's done so well this year, I hope it makes it through the winter. I started with one little spearmint plant this spring, that is now six big plants :)

LB spread by self-seeding. But as Fatamorgana said, it is very easy to get rid of them if you don't want them; just weed them out. It is also very easy to idfentify them frome the shape of leaves.I consider a plant invasive when it propagates throuGH root system and you cannot find them all to eradicate them. Only mints fit my definition of invasive. There are tens of weeds that are more invasive than LB and we know how to contain them: by WEEDING.