Yes, Liriope does spread...and spread...and spread (I am in Northern Virginia). 20+ years ago, a landscaper put in three or so plants when he built a dry creek bed to handle water during heavy rain. So pretty at first. Now, it has spread everywhere, choking out some of my native plants. It is impossible to get rid of, so I think I will need to hire someone to dig it all up which is a sisyphean task. I now have planted a native Carex here which will not be invasive. I have several Carex flaccosperma in a new area where i am creating another native garden in the front yard. It is a blue sedge and lovely.

I am sorry that I don't really have advice for you. The only thing I can say is that spacing really doesn't matter too much since it will fill in pretty quickly. Just plan for the mature size if you really want liriope and watch out for small plants coming up where you don't want them.

Only ONE form of liriope spreads aggressively - Liriope spicata. Liriope muscari is a tidy clumper so spacing is no issue with the first but more of a practical concern with the second.

Cutting out chunks for transplanting with a sawzall or old pruning saw is an effective and efficient method.

Always, always ALWAYS start with where in the world you are. Here, liriope spreads, but is controllable.

Things like this are best divided with the two fork method, which pries the plants apart, instead of cutting them apart.

https://www.tracylive.com/tag/double-fork-method/

i have the spreading variety. that's why the gaps. i did have my location with my name at one time. not sure why it went away. when i try updating my name it keeps sending me thru a loop.

Thank you gg, yes, I assumed he has the spicata because he mentioned spreading. My mistake.