This grower is sure of this plant identification.
Purple loosestrife, Purple willowherb, Spiked loosestrife, Loosestrife
Lythrum salicaria (Purple loosestrife). This species will produce dramatic and colourful flowering spikes and is well-known for its rampant invasiveness. This plant is often found in the wild in Northern Europe.
They will grow in most soil conditions as long as there is moisture.
Wildflower/meadow, border, bog, semi-aquatic.