Purple Loosestrife Seeds Lythrum salicaria - is a tall wetland plant that produces spectacular spikes of purple flowers in late summer. It will grow well in full sun or semi-shade and is often visited by damselflies and dragonflies on warm summer days. Purple loosestrife is most often associated with lakesides and pond edges. Shortly after flowering, plants shed their foliage for the winter, however the seed-heads remain of value for a wealth of over wintering insect life. In a wildflower garden, Purple loosestrife can be included around the margins of a pond and once established, can be propagated fairly easily from cuttings. Purple loosestrife looks beautiful growing alongside other late flowering wetland plants such as Devil’s bit scabious, Water mint, Hemp Agrimony and Fleabane