Sweet woodruff

Sweet woodruff: how do you recognise it?

Habit

Low carpet 15–20 cm high that spreads quickly by underground runners.

Leaves

Narrow, lance-shaped leaves in whorls of 6–9 around a square stem; glossy fresh green.

Flower

Small white, four-petalled stars about 5 mm across in loose clusters, from April to June.

Scent

Fresh, it hardly smells; as it wilts and dries, a sweet hay scent is released.

Fruit

Small round fruits with hooked bristles that cling to clothing and fur.

Roots

Fine, creeping rhizomes just below the surface.

Flowering: April–June · Harvest and fruit: April–May · Plants: March–April and September–October · Pruning: March and June

Why grow it?

• A fast, native ground cover for the shade under shrubs, trees and hedges.
• Fresh green leaves from spring to autumn and white stars in April–June.
• Dried leaves smell of hay and vanilla: lovely in a scented sachet in the linen cupboard.
• Flowers early in the year and attracts small insects then.
• Keeps weeds down and needs almost no work once established.

Sweet woodruff: where does it grow best?

• Partial to full shade, under deciduous shrubs and trees. In full sun the leaves scorch and it dries out.
• Humus-rich soil, ideally with leaf mould: sand, loam or clay, acid to chalky.
• Moist to wet; in dry soil it shrivels in summer.
• Plant 25–30 cm apart; the carpet closes after one or two years.
• Give it a spot where it is allowed to spread, or keep it in check with an edging.

Light

Partial shade and shade

Soil type

Sand, loam or clay

Acidity

Not fussy

Moisture

Normal or wet

Size

0.2 m tall, 0.5 m wide

Hardiness

Hardy (to -35 °C)

Goes well with

• Ferns: Tall, elegant fronds above the low carpet.
• Solomon’s seal: Arching stems with white bells that flower at the same time.
• Wood anemone: A native spring flower that blooms early in the year among the carpet.
• Bluebell: Blue bells in May above the little white stars.
• Hosta: Large leaves as a contrast with the fine foliage.

Sweet woodruff: when and how to plant it?

Plant in March–April and September–October.

1. Plant in March–April or in September–October, when the soil is moist.
2. Loosen the soil and mix in plenty of leaf mould.
3. Set the plants at the same depth as in the pot and firm them in.
4. Space them 25–30 cm apart; allow 9–12 plants per m².
5. Water straight away and keep the soil moist for the first few months.
6. A thin layer of leaf mould or shredded leaves between the plants helps the carpet close faster.

Care

Water

In dry spells in the first year. Later only in prolonged drought: the leaves then shrivel, but the plant usually shoots again.

Feeding

Not needed; leave fallen tree leaves in autumn, they provide food enough.

Keeping it in check

In spring, cut back the edge with a spade if it goes too far or overruns other plants.

Harvesting

Pick stems just before or during flowering and dry them in an airy, shady place for a scented sachet.

Weeding

For the first few years, weed between the young plants until the carpet has closed.

Tip: In May, pick a bunch of flowering stems and let them wilt for a day or two: only then is the typical hay scent released. Hang them in a cupboard or tuck them between the linen.

Sweet woodruff: when to prune it?

Pruning months: March and June.

When: Hardly any pruning is needed. Cut out old stems in March and, if the carpet looks untidy after flowering, shear it back in June.

How:

• In March, remove old, dried stems if they get in the way of the new leaves.
• After flowering, cut the stems back to a few centimetres with shears; it soon regrows fresh and green.
• Chop off runners that spread over paths or into other plants.

Caution: Do not cut back during a dry spell without watering afterwards: it then struggles to regrow.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Division

In March–April or in September–October: lift slabs of the carpet with a spade and replant them elsewhere. Loose pieces of rhizome with a few shoots also take easily.

Seed

Sow ripe seed outdoors in autumn; it needs frost and germinates slowly and erratically. Division is much quicker.

Sweet woodruff: how does it get through the winter?

Hardy to −35 °C.

• Very hardy, to about −35 °C: no protection is needed in Belgium.
• The leaves largely die back in winter; in mild winters some stay green.
• Leave fallen tree leaves in place: they protect the roots and later turn into humus.

Diseases and pests

• Shrivelled leaves: Brown, dried leaves in summer, due to drought or too much sun. Water; if the spot is too sunny, move it into shade.
• Spreading: It overruns smaller plants. Cut back the edge every spring and pull out runners.
• Weeds in a young planting: Until the carpet closes, weeds grow in between. Hand-weed and mulch with leaf mould.
• Bare patches: On poor, dry soil the carpet thins out. Spread leaf mould and fill in with divided pieces.

Through the year

• March: Cut out old stems. Plant and divide.
• April: Flowering begins. Plant. Cut back the edge.
• May: Flowering. Pick stems for drying.
• June: Last flowers. Shear back after flowering if needed.
• July: Water in prolonged drought.
• August: Water in prolonged drought.
• September: Plant and divide.
• October: Plant. Leave fallen tree leaves in place.

Edible and useful

Leaves (April–May)

Cut the stems with their whorls of leaves in April and early May, just before or as flowering begins. Fresh, they hardly smell; let them wilt for a few hours and their lovely scent of hay and vanilla (coumarin) is released. Classic for May wine (Maibowle), but also in syrup, cream or ice cream.

Storing

Dry the stems in bunches, hung upside down somewhere airy and dark: dried sweet woodruff smells strongest. Keep it in a closed jar for up to a year; a bunch in the wardrobe keeps moths away and smells fresh.

Caution: Sweet woodruff contains coumarin: in large amounts it causes headaches and can damage the liver. Use no more than 3 to 5 g of fresh herb per litre, let it steep for half an hour at most and do not drink it every day. Not during pregnancy, not for children and not with blood thinners. Only pick before flowering, and only in your own garden: in the wild it grows in ancient woodland.

Eating and using is at your own risk: see the terms of use.

Recipes

• May wine (Maibowle) (Liqueur · ± 1.5 litres · 15 min + 3 hrs wilting)
• Sweet woodruff syrup (Syrup · ± 500 ml · 20 min + 3 hrs wilting)

Did you know?

• The hay scent comes from coumarin, a substance released as the leaves wilt; the same substance gives freshly mown hay its smell.
• Its Dutch name, meaning ‘Our Lady’s bedstraw’, recalls the old use of dried bedstraws as a fragrant filling for mattresses.
• The little fruits have hooked bristles and cling to animal fur; that is how it spreads through the woods.