HoneyHQ

Purple loosestrife

Lythrum salicariaLythraceaeHerbaceous perennial

A tall magenta spike of a plant along European river banks, and one of the most productive nectar sources on wet ground. It also carries one of the most elaborate breeding systems in botany — three distinct flower forms with styles and stamens at three different heights, so that pollen from one level fertilises only a style at the matching level. Darwin worked it out and called it the most remarkable arrangement he had studied.

Where not to plant it

Severely invasive across North America, where it forms dense monocultures in wetland and displaces native vegetation. Listed and prohibited in many US states and Canadian provinces, with biological control programmes running against it. A first-rate bee plant in Europe and a genuine ecological problem outside it.

Value to bees

Nectar
Very high
Pollen
High
As a honey crop
Major honey crop — yields a surplus in good years
Which bees, and why
Worked heavily by bumblebees, honey bees and butterflies. The three-form breeding system means a bee carries pollen at three positions on its body and delivers each to the matching style, which is a genuinely remarkable piece of coordination between plant and insect.

Open six-petalled flowers with nectar within easy reach — accessible to short-tongued bees as well as long-tongued ones.

Worth knowing
Among the top nectar producers in the European flora, delivered over a long late-summer window on ground that offers little else.

Flowering

In flower
June to September (northern hemisphere)

A long window through high summer, with each spike opening gradually over weeks.

When nectar flows
Exceptionally productive. Purple loosestrife is one of the highest nectar-yielding wild plants in Europe and it secretes reliably on wet ground through dry summers.
Year-to-year variation
Very dependable, and a genuine honey crop where it dominates wetland — notably across parts of North America, where it is invasive.

What it does to the honey

Where a surplus is taken, loosestrife honey is amber, slightly astringent and distinctly herbal. In parts of the northern United States it is a significant late-season crop from an invasive plant, which is an uncomfortable position for a control programme.

Growing it

Conditions
Sun, wet to permanently moist soil. It thrives in shallow standing water and pond margins.
Size
1-1.5 m.
Native range
Europe, Asia and North Africa, on river banks, fen and wet meadow.
Suits
Meadow or wildflower area, Large gardens
  • An outstanding plant for a pond margin or a wet corner, and one of the best nectar plants available for such places in Europe.
  • Do not plant it in North America, Australia or New Zealand. It is a serious wetland invasive there and is prohibited in many jurisdictions.
  • In its native range it is well behaved and supports a specialist beetle fauna that keeps it in check.

What it looks like

Upright square stems with willow-like leaves and long dense spikes of six-petalled magenta-purple flowers opening from the bottom upwards.

Sources

  • Field Guide to the Bees of Great Britain and Ireland — Bloomsbury (2015) · Field guide
  • HoneyHQ editorial synthesis — HEKNO Ltd · HoneyHQ synthesis

How sources are selected and weighted is set out in the sources and evidence policy.

Guides covering this plant

Tools for planning planting

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