Weed ID help please

alicegorman93

Hi,

We recently bought a house and found this growing in a rocky patch down between two sheds, alongside some hedge bindweed. Can anyone tell me what it is? I panicked it was knotweed but the leaves are opposite and I think knotweed leaves are alternating?

Not sure if its always red or because its growing in rocks and probably nutrient deficient.

Thanks!

Buttercupdays

Willowherb.  There are lots of different ones, but they often have reddish leaves and stems.