Tufted loosestrife

Tufted loosestrife: how do you recognise it?

Habit

Straight, unbranched stems 40–50 cm tall from a creeping rhizome; a clump grows to about 40 cm across and slowly spreads.

Leaves

Narrowly lance-shaped, 5–10 cm, opposite and stalkless; fresh to dark green.

Flowers

Dense, rounded clusters 1–3 cm long on short stalks in the leaf axils halfway up the stem, from May to July.

Colour

Yellow; the long stamens stick out beyond the narrow petals and make the clusters look fluffy.

Roots

Creeping rhizomes in wet soil or shallow water.

Flowering: May–July · Plants: April–June · Pruning: March

Why grow it?

• A rare native species that you can give a safe home in the garden.
• Unusual yellow tassels of flowers in the leaf axils, from May to July.
• Bees and hoverflies visit the flowers.
• Grows where it is really wet: in boggy, peaty soil and down to 10 cm under water.
• Straight, fresh green stems that give the pond edge a natural look.

Tufted loosestrife: where does it grow best?

• Sun or partial shade; it flowers best in sun.
• Wet, peaty or loamy soil, acid to neutral; avoid chalky soil and hard water.
• Marsh zone: from boggy bank down to 10 cm below the water surface.
• The soil must never dry out, not even in summer.
• Allow about 40 cm per plant, in a spot where large, vigorous spreaders will not crowd it out.

Light

Sun and partial shade

Soil type

Loam or peat

Acidity

Acid or neutral

Moisture

Wet

Size

0.5 m tall, 0.4 m wide

Hardiness

Hardy (to -30 °C)

Goes well with

• Bogbean: Fringed white flowers in spring, in the same acid, wet soil.
• Water forget-me-not: Little blue flowers at its feet while the loosestrife flowers yellow.
• Marsh cinquefoil: A native bog plant with dark purple flowers, also suited to peaty soil.
• Yellow flag iris: Large yellow flowers at the same time, with tall, sturdy leaves.

Tufted loosestrife: when and how to plant it?

Plant in April–June.

1. Plant from April to June.
2. In the pond, use a basket of acid, loamy aquatic compost, perhaps with a little leaf mould added; no potting compost with chemical fertiliser.
3. Set the plant at the same depth as it was in its pot, firm it in and top the basket with gravel.
4. Stand the basket 0–10 cm below the water, or plant straight into the wet bank.
5. Space plants 30–40 cm apart.
6. Top up with rainwater and keep the soil thoroughly wet for the first few weeks.

Care

Water level

Keep the base wet at all times; top up with rainwater in dry summers.

Feeding

Not needed: it likes a poor, wet spot.

Runners

In spring, chop off runners that wander too far.

Old stems

Leave them until late winter: they protect the rhizome and give insects shelter.

Division

Every three or four years, divide in April once the centre of the clump becomes bare.

Tip: Plant it in a basket of its own at the wet edge, away from large spreaders: that gives this modest plant room to spread slowly.

Tufted loosestrife: when to prune it?

Pruning months: March.

When: It needs hardly any pruning. In March, cut off last year’s dead stems.

How:

• In March, cut old stems back to just above the soil or water, before the new shoots come up.
• Leave the stems standing in autumn: they protect the rhizome and shelter insects.
• There is no need to remove the faded flower clusters.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Division

In April–May, chop off a piece of rhizome with a few shoots and replant it separately in wet soil or a basket.

Runners

In spring, detach rooted runners and plant them in a new basket.

Tufted loosestrife: how does it get through the winter?

Hardy to −30 °C.

• Fully hardy, to about −30 °C: it comes from cold regions and needs no protection.
• The stems die back in autumn; the rhizome overwinters in the wet soil.
• It can stay outdoors in a tub too; just make sure the soil never dries out.

Diseases and pests

• Few flowers: Not every stem flowers; in shade and in soil that is too dry it flowers even less. Give it a sunny, wet spot.
• Aphids: On young shoots in spring. Hose them off with water; ladybirds do the rest.
• Slugs: They eat young shoots on the bank. Pick them off in the evening.
• Crowded out: Large spreaders such as common reed or reedmace swamp it. Give it its own basket or spot.
• Yellow, sickly leaves: Often a sign of hard water or chalky soil. Top up with rainwater.

Through the year

• March: Cut off old stems.
• April: Plant or divide. New shoots appear.
• May: Flowering begins in the leaf axils.
• June: Full flower. Last month for planting. Top up with rainwater.
• July: Last flowers. Keep an eye on the water level.
• August: Top up the water in dry spells.
• October: Leave stems standing as winter protection.

Good for wildlife

Bees

Nectar and pollen for honeybees and wild bees.

Did you know?

• The flowers are not at the top but halfway up the stem, in the leaf axils: that is how you recognise it at once among other loosestrifes.
• The name thyrsiflora refers to the dense flower cluster, a thyrse, named after the staff of the Greek god Dionysus.
• It grows right across the northern hemisphere, from Scandinavia and Siberia to Canada.