Square-Stalked St Johns Wort Seeds hypericum tetrapterum – grows in damper soils than Common St John’s wort where it attracts insects such as bees and butterflies. In gardens it can be introduced into boggy areas, wet grassland or grown around the edge of a pond. Square Stalked St John`s Wort typically grows to about 50 cms in height and has yellow flowers with orange centres that appear mainly in July and August. It looks best growing with other wetland plants such as Meadow sweet, Purple loosestrife, Common Fleabane, and Coomon meadow-rue.