Description
Lythrum salicaria, known as purple loosestrife, is a tall UK native wild flower of reedbeds, fens, marshes and riverbanks. Through the summer it carries dense spikes of vivid purplish-pink to magenta flowers.
Purple loosestrife at a glance
| Botanical name |
Lythrum salicaria |
| Common name |
Purple loosestrife |
| Plant type |
Upright, clump-forming perennial; dies back in winter |
| Height and spread |
About 1–1.5 m tall, up to 50 cm wide |
| Flowers |
Vivid purplish-pink to magenta, in dense spikes, June to September |
| Position |
Full sun |
| Soil |
Reliably moist to wet clay or loam; any pH |
| Pond depth |
0–10 cm of water over the crown |
| Hardiness |
RHS H7 – very hardy (below -20°C) |
| Native to |
UK and Ireland (native wild flower) |
Is purple loosestrife good for wildlife?
Yes. It is on the RHS Plants for Pollinators list, and its nectar feeds long-tongued insects such as the brimstone butterfly, red-tailed bumblebee and elephant hawk-moth.
Where to plant it
- The shallow edge of a wildlife pond, 0–10 cm deep
- Bog gardens and wet mud
- A sunny spot
How to plant and care for it
Plant from spring to late summer. Cutting the shoots back in spring reduces its height. Deadhead after flowering to stop self-seeding. Dark speckles on the lower leaves in summer are normal.
Is it invasive?
Not in the UK, where it is native and not restricted, though it self-seeds freely. It is a serious invasive weed in North America, so do not send it abroad. Buy nursery-grown plants rather than collecting them from the wild.
Which size should I buy?
Bare-root plants (7 cm, 9 cm, 1 litre and 3 litre) arrive without a pot or compost and are the most economical way to plant a group. Potted plants (9 cm, 1 litre and 3 litre) arrive growing in our peat-free compost and give a faster display. Packs of 3 come in 7 cm, 9 cm, 1 litre and 3 litre bare-root sizes and cost less per plant. The 2x Pot & Compost option is two plants supplied with pots and compost.
