Controlling Vigorous Plants
I have tall phlox and Lysimachia clethroides growing in my perennial garden, and they’re starting to take over the beds. I keep digging them up to no avail.
Regularly deadhead these plants to prevent reseeding and new seedlings growing in the garden. This is usually enough to keep garden phlox in bounds. The Lysimachia, also known as gooseneck loosestrife, also spreads by rhizome and needs a bit more control. Divide these plants yearly to keep them in bounds. Or grow them in a location where they have plenty of room to grow or are contained by walks, walls and other barriers. In the meantime invite some gardening friends, with space to fill, to share in the bounty of plants. Just let them know the secret to controlling these vigorous garden beauties.