Hi. I have a bee balm plant. it started the year in a small lot from the garden store and now it's getting pretty big. I am reading that it spreads via rhizomes. I'm not really sure what that means. Will it keep spreading and spreading forever? How do I keep it from overrruning other flowers? Can I stick a board in the ground vertically to create a barrier?

That's a good question. I love my Bee Balm but it is widening every year. If there are rhizomes down there, when it gets too big, take you shovel, cut off half and plant it someplace else (or gift it to a friend). My daughter started one from a broken stem on mine. I didn't know you could start them from cuttings but she did - I think just to prove her mother wrong.

By the way, your's is really pretty and full. Mine is a little sparse this year - our usual summer rains have not happened.

Rhizomes are underground (usually, although they can be above ground as well) stems that grow away from the mother plant. At intervals along the length of the rhizome, at the "nodes", the plant will produce a new set of roots and aerial stems. Plants with rhizomes do spread, but the rate at which they do so varies greatly.

Monardas generally don't spread all that fast and are fairly easy to deal with. If they start to crowd other plants, just take a shovel or digging knife and carve off the unwanted sections and either plant them somewhere else or throw them away. It won't hurt the rest of the plant.