lariope & milkweed
Bought a new home that included lariope in the flower beds. I wanted a much different look & thought digging out the lariope wouldn't be a big deal. How wrong I was! In addition, I tried spraying RoundUp on both plant & roots. --ineffective. How canning remove these plants? Second, I understand planting milkweed will attract Monarch butterflies. I 've heard it spreads rapidly. Is it as difficult to contain as the lariope?
There are clumping and running species of liriope. The running type is especially hard to get rid of, but both can be eliminated by persistence. Sometimes when the glyphosate (roundUp) is applied is important. Late summer-early fall is a prime time. Also, it's often necessary to spray more than once. So, don't despair. You could also try covering the area with black plastic for the rest of the summer and suffocating it.
Most domesticated milkweed (swamp milkweed, butterfly weed) will spread slowly where happy, provided deer don't eat it. Have never had a report that it was a problem to control. However, wild native milkweed grows suckers and is big and aggressive. It is not used as a landscape plant in a more manicured part, but rather in a wild, native part. So that answer depends on what milkweed you had in mind.