Lysimachia thyrsiflora - Tufted Loosestrife, Native Pond Marginal Plan

Lysimachia thyrsiflora, known as tufted loosestrife, is a scarce UK native of fens, lake margins and ditches. Its upright stems carry pairs of narrow, pointed leaves and, in summer, dense, fluffy clusters of small yellow flowers from the leaf joints.

Tufted loosestrife at a glance

Botanical name	Lysimachia thyrsiflora
Common name	Tufted loosestrife
Plant type	Upright perennial; dies back in winter
Height and spread	About 60 cm tall (up to 1 m), 50–100 cm wide
Flowers	Small, yellow, in dense, fluffy clusters along the stems, in summer
Position	Full sun or part shade
Soil	Permanently moist or wet clay or loam; any pH
Pond depth	0–15 cm of water over the crown
Hardiness	RHS H5 – hardy in a cold winter (-15 to -10°C)
Native to	Britain (a scarce native; not native to Ireland)

Why grow tufted loosestrife?

It is designated Scarce in Great Britain, with most wild sites now in Scotland. It has been lost from North Lincolnshire, once the southern edge of its range. Growing it in a garden pond helps keep it in cultivation. Always buy nursery-grown plants, never dig them from the wild, and do not plant it out near wild populations.

Where to plant it

The shallow margin of a wildlife pond, 0–15 cm deep
Wet clay or loam beside a pond or ditch

How to plant and care for it

Plant in spring or summer. It spreads by creeping roots to form a clump. It can be shy to flower. It is generally free of pests and diseases.

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 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.