Onagraceae: An erect perennial herb typically growing to a height of 1m or more and can have several stems. Found in damp woodland clearings, hedge banks, ditches and cultivated soil. The flowers are pink with four notched petals, eight stamens and an undivided, club shaped stigma. Blooming from July to August. Square-stalked willowherb has an erect, hairless stem with four conspicuous raised ridges running down it, hence the name. Europe, including Britain, from Sweden south and east to Western Asia.
The leaves can be cooked for use as a vegetable.
A good food plant for the Elephant Hawk Moth caterpillar (Deilephila elpenor).
Surface sow seeds, warm. Easily established form seed sown in the autumn or spring. Succeeds in most soils, preferring a well-drained but moisture retentive soil in a sunny position.