Purple Loosestrife

No suggestions apart from pulling it up by the root which would take ages, as it spreads seeds so quickly. It can look OK swaying in the breeze but of course you may have too much of it.

annodomini, it must be happy in the soil conditions, so maybe go with the flow and make it look deliberate by building a border around it? You could then surround that with a gravel path so it's easy to pull up the unwanted roots.

Some seeded in my garden a couple of years ago. I knew it would spread but don’t mind as it’s so pretty. I have pulled a couple of bits out but the rest is very welcome. Free plants!

It will spread like wildfire if you don’t dig it all out. I find it likes to hide under the leaves of other plants, so pulling out all the seedlings before they get enmeshed is least disruptive.

There's that old gardeners' saying about mare's tale.
Q. When's the best time to weed out mare's tale?
A. Sunday.
Q. Which Sunday?
A. Every Sunday.

The same applies to Purple Loosestrife. Just keep digging out a little clump every time you garden and try to do it before it sets seed.

I have a feeling that the mare's tail is about to keep it company! Thanks for all your comments. You have confirmed my suspicions!

The bees love it!
I have a pink version too. The seedlings are very easy to pull up, as are the adult plants, just do it before they set seed.

I have it as well, and quite like it, especially when it grows through the bamboo. It seems to prefer growing in the planters and paving. So far it’s stayed out of the flower and veg beds.