Lythrum salicaria
Purple loosestrife
Common names: Common purple loosestrife
At a glance
- Light
- Full sun
- Pot size
- from 20 l
- Lifespan
- Perennial
- Flowering
- Jun–Sep
- Hardiness
- Hardy
- Origin
- Native to Germany
Photo: Ivar Leidus · CC BY-SA 3.0 · Source
This description was machine-translated.
Description
Purple loosestrife is a native riparian perennial that bears purple flower spikes from June to September, making it one of the most striking summer flowers along pond edges. In the wild it is found along stream runs, banks, and damp meadows, making it an excellent choice for garden ponds or wet areas in beds. Bees, bumblebees, and butterflies visit the flowers throughout the summer, making the species a valuable pollinator-friendly plant. The botanical name is Lythrum salicaria; the German name is sufficient for everyday gardening.
Care instructions
Plant purple loosestrife in a sunny to partially shaded spot with consistently moist to wet soil, such as near a pond or in a marshy zone. Set out seedlings in spring, from mid‑May (week 20), at spacing of 40 to 50 cm to allow the clumps to develop well. Water heavily during dry summer weeks, as the plant tolerates waterlogging better than drought. Cut back the spent stems in autumn or early spring, so that the seed heads provide additional food for birds over winter. The wild form is hardy and is usually cultivated without winter protection.
The care notes were machine-translated from German.
Garden year
FloweringJun–Sep
Soil & site
Soil pH
Soil type
moist, nutrient-rich, loamy, clayey
Purple loosestrife comes from riverbank and silting-up zones and accordingly wants it moist to wet. A nutrient-rich, loamy to clayey soil with good water retention suits it best, and the plant also shrugs off occasional waterlogging. In normal bed soil without a damp site it stays much smaller and flowers less.
Feeding
Medium feeder
Months
Apr, Jun
A dose of mature compost as growth begins is usually enough for the whole season. If purple loosestrife grows at the edge of a pond, well-rotted compost or aged manure is the right choice, as it does not leach nutrients into the water. A second, light dose of compost at the start of flowering in June supports the long flowering period into late summer.
Overwintering
Purple loosestrife retreats to the rootstock in autumn and, as a native perennial, is completely hardy. You can leave the spent stems standing over winter; they offer insects shelter and the plant some protection from the cold. In early spring, cut the old shoots back close to the ground before new growth comes.
Propagation
Methods
- From seed
- Division
- Cuttings
The easiest way is to divide the rootstock of established plants in spring or autumn and plant the divisions straight into their new, damp site. Sowing also works well; as cold-stratification seeds, the fine seeds prefer to germinate after a frost period and with plenty of light at the surface. Cuttings of non-flowering shoot tips in early summer also root reliably in moist substrate or directly in a glass of water. Note that purple loosestrife easily self-seeds near a garden pond; regularly removing the seed heads keeps the stand in check.
For your garden
Grow Purple loosestrife yourself
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