All I can say is be careful as it is very evasive..as it is the mint family....
I like that an evasive plant. The cultivar should be named after a politician. Perhaps after famous spin doctors. They are evasive.
While not familiar with this particular member of the mint family, characterizing mints as invasive is a calumny. Sure several of the mints should have cultivar names like "Genghis Khan" or "Tamerlane" but remember that basil, coleus, oregano, and a bunch of other herbs are also mints and in our climate survival is the best we can do.
Walkers Low Nepeta is easy from division. The plant does not set seed since it is sterile. I don't believe it is invasive, since besides a hard cutting back after it's initial bloom we have never seen the propensity for spreading in any of the gardens we work in. The plant is named after an English gardener whose name is " Walker Low". Hope this helps.
Walkers Low is very easy to propagate. All of mine are started from cuttings. I take cuttings in May and June, stick them in an organic sterile mix in premoistened flats and put them in a covered shaded house. They do not require any rooting hormone and will root in 3 weeks. I have NO heat in my shaded house and these cuttings will still root with fluctuating temps of 50s at night and 80s during the day. You cannot ask for a more willing plant!
I don't consider them "invasive" but instead, vigorous. Invasive plants throw seeds all over the place and come up under sidewalks etc. Walkers Low just gets a bit sprawly and that is remedied by cutting it back. My Heliopsis is more invasive than Walkers Low.
Anyway, there is no big secret to propagating this plant. Just watch out for spider mites and occasional aphids...no serious pests other than those.
Good luck
Annie
Grasshopper Perennials
Knoxville, MD