I grow lovage in my Zone 8 herb garden. It gets about 6-7' tall and has clumped out in proportion to its height but has not been overly aggressive. I do find seedlings now and again but they are easily pulled out, and they are not a nuisance. I initially planted three 4" pots which was entirely overkill. One is plenty. Or perhaps 2-3 spaced out so they become a repeating theme rather than a hedge. Here's a photo before it blooms, with elecampane and sea holly next to it. I have since moved the sea holly (it was getting drowned) and have let the elecampane spread out next to the lovage. They are both quite tall but with much different foliage and flowers. Lovage will stand on its own, but I have problems with elecampane leaning over (not happy about that). What the heck, you have it, plant it. You may love it (ha ha).
