probably came from a nearby bird feeder ... and that was why.. back in the day.. i moved my feeders to be over the cement driveway ... rather than all the seed falling in the garden ... ken

Realistically, you have two choices with a well grown invasive plant like this bittersweet. One is to cut to the ground all vines and on the fresh cuts paint a brush killer. Yes, it uses herbicide, but in smaller, very targeted use. This might take one repetition, but I haven’t had times when even a well established invasive takes more than one repetition. Otherwise, cut all the stems, and as soon as it resprouts, remove them before they are fully leafed out, and then repeat for the next two or more growing seasons every week or so. The goal here is to prevent it ever regrowing enough leaves to create energy so that the plant uses up all its reserves and is unable to replace them. With bittersweet, new stems won’t just grow from the main stem area, but will sprout from roots as well. If you let it establish leaves, it will start replacing the energy it used up trying to regrow, so this will take persistence and consistency. When a plant is really large and inter-grown with other plants like this, you won’t be able to remove all the roots with anything less than a tractor or bulldozer.

Ken, thanks for your comment! LA is just initials from my name, I live in Lisbon, Portugal. I brought it inside just to see if it can do well since I like how it looks. It was outside under a tree, so it was only in full sunlight for no more than a couple hours a day. It was in an old pot and nearly dead, had no leaves on it and somehow survived. So even though I don't know what kind of plant it is I'm thinking it's very sturdy and should hopefully be OK inside in a hallway that doesn't get too much light? I might be wrong. Do you know what kind of plant it is?

You can get pink spiky flowers from Veronica, Salvia, Agastache and Obedient plant. You'd have to find cultivars with the right height and color. The fuzzy purplish spikes in the front part of the border look like perovskia to me, but it could be lavender. You'd need a short cultivar of perovskia. Between the pink, there are other plants, probably to bloom at a different time. My hydrangea bloom later in the summer, so you'd want some spring blooms. Between the lady's mantle (alchemillea mollis) and lamb's ear, there's another plant. Hard to identify, but I might suggest a moss phlox. It will bloom in the spring and you can get them in pretty much every shade from purple to pink to white. They should be native to you. I hate lady's mantle. It spreads like crazy and is hard to get rid of. It looks lovely only when a few dew or raindrops are on the leaves. It gets dull in the summer heat and I'm in Maine, on the coast, so almost certainly get less summer heat. You might put in a lime-colored heuchera in its place. You'll get the lime (the color of the lady's mantle flowers) year-round, heucheras are native (lime is not a native color, though). And you won't get the stuff in your lawn. The heuchera won't like too much sun, though. So, bottom line is check sizes to ensure you get cultivars that will be the right height for your design. Check bloom times so your garden has something blooming in all seasons, and check for sun/shade.