I got an existing small patch(10ftx5ft) of cattails(typha latifolia) in my somewhat wetlands garden that I planted last summer after digging and dividing the rhizomes of them from another section in my garden. So before its too late I’d like to install a root barrier around it with clamps. Just like how you would treat bamboo. My question is how deep do I need to dig the trench for the barrier. 1.5 ft? 2ft? Been trying to look up how deep cattail roots grow but no info. It says it can grow up to 4 ft in standing water but thats about it.