I have been invaded by evening primrose, Oenothera specisosa which I bought from Benke Nursery a long time ago after visiting lady Byrd Johnson's parl sanctuary . I was told it was an easy plant to grow, never told it ws invasive and planted 3 quarts in my elevated flower bed in front of some tall fastiagata boxwood. Well, it was very pretty but it started to invade my garden everywhere. Since I live in a rural area and have about 3 acres of property with 900 feet of waterfront, I did nto mind but now, it has gotten to a point when it is a big nuisance. in one of the garden room, I have lots and lots of bulbs, both spring and fall and I could nto see them at all a the8 are covered. So, 3 years ago, I pulled all the evening primrose but they returned . Now I was advised that if an part of the root remains, it will resprout. I have been at this area of the garden alone for 2 weeks, pulling rain ro shine and am exhausted I see a lot of roots deeper than 4 inches, large caliber, and some medium and fine white ones about the diameter of a hair. . If I dig deeper, I see even larger root, the diameter about that of my fingers. I do not use herbicide for personal reasons and cannot use black tarp to cover and hopefully kill them as I wil oil my bulbs and other plants How deep do I. have to dig up those roots? . How far wil they travel? I do not mind keeping the ones along the bulkhead but worried it may come back to my flower beds. &T hanks