Ground-ivy

How to recognise it

Habit

Creeping perennial with long runners that root at the nodes and upright flowering stems of 10–30 cm. Forms dense mats.

Leaf

Opposite, round to kidney-shaped, 1–4 cm, with a scalloped edge and a long stalk. Smells strongly aromatic, a little minty, when crushed. Often tinged purple in winter.

Flower

Blue-violet two-lipped flowers of 1.5–2 cm with dark spots on the lower lip, in twos or threes in the leaf axils. Some plants have larger flowers with both sexes, others smaller, female-only flowers.

Stem

Square, as in all members of the mint family, often tinged reddish purple and slightly hairy.

Fruit/Seed

Four small brown nutlets at the bottom of the calyx. The plant spreads mainly by runners.

Confusion with

Bugle has oblong leaves and flowers in an upright spike, without scent. Red dead-nettle has triangular, hairy upper leaves and pink flowers, and does not creep.

Flowering: March–June · Pruning: June

Why grow it?

• Flowers from March, feeding bumblebee queens, hairy-footed flower bees and bee-flies just out of their winter rest.
• A creeping ground cover for places where grass grows poorly, such as under trees.
• Tolerates mowing and trampling, so it fits easily into a flowery lawn.
• The leaves stay green in mild winters and give shelter to small soil creatures.
• It was once used to clear and flavour beer, before hops became common.

Ground-ivy: where does it grow best?

• In the wild: damp deciduous woods, woodland edges, hedges, rough ground, dykes, verges and grassland, especially on nutrient-rich soil.
• In the garden: partial and full shade under trees and shrubs, but also sun if the soil does not dry out.
• Moist to damp, humus-rich soil; clay and loam are ideal, on dry sand it stays small.
• Very suitable for a flowery lawn under trees, a woodland edge or as ground cover between shrubs.

Goes well with

• Lesser celandine: Yellow stars in March, in the same damp, shady spots.
• Sweet violet: Fragrant purple flowers in March–April, lovely among the blue ground-ivy.
• Bugle: Blue flower spikes in May, also a creeping ground cover.
• Wood anemone: White flowers in spring under trees.
• Garlic mustard: White flowers in April above the carpet, and food plant of the orange-tip butterfly.

Ground-ivy: when and how to plant it?

1. Buy a few plants from a native plant nursery or ask for a piece of runner from someone who already has it in their garden. Never dig plants up from the wild.
2. Plant in March–April or September–October, 30–50 cm apart: the runners soon fill the gaps.
3. Firm the plant in well and lay the runners on the ground; where a node touches the soil, it roots.
4. Water when planting and keep the soil moist for the first few weeks.
5. Sowing is possible too: sow in autumn or early spring on bare ground and barely cover the seed.

Care

Water

Only after planting and during long dry spells. In shade it usually copes.

Feeding

Not needed. On rich soil it grows vigorously enough already.

Mowing

In a lawn you can simply mow; leave a few patches unmown from March to May so it can flower.

Spreading

Regularly pull out runners creeping into the border; they root shallowly and come out easily.

Ground cover

Under shrubs, let it do its thing: it keeps the soil covered and moist.

Tip: For a flowery lawn under trees, leave a strip unmown until June: ground-ivy, daisies and speedwells can then flower for the bumblebees first.

Pruning and mowing

Pruning months: June.

When: After flowering, in June, or whenever the runners go too far.

How:

• Cut or mow the long flowering stems short after flowering; the plant becomes compact and fresh again.
• Cut runners that creep over paths or into the border and pull them out, roots and all.
• In winter there is nothing to do: the leaves partly stay green.

Caution: Do not leave pulled-out pieces lying on damp soil: every node can root again. On the compost heap they are fine.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Runners

In spring or early autumn, cut off a rooted runner and plant it elsewhere. This almost always works.

Division

In March or September, lift a piece of the mat with a spade and split it into smaller pieces.

Seed

Sow in autumn or March on bare soil. Germination is fairly slow; runners are quicker.

Ground-ivy: how does it get through the winter?

Hardy to −30 °C.

• The leaves stay green in mild winters, often tinged purple; in hard frost some of the foliage dies back.
• Fully hardy: roots and runners survive hard frost.
• The dense mat protects the soil and shelters small soil creatures.
• By February–March it is growing again, ready for the first bumblebees.

Diseases and pests

• Spreading: In a damp border it can smother lower plants. Pull out the runners regularly, especially in spring.
• Galls: Small balls or points on the leaves are galls made by tiny gall wasps or gall midges. Harmless, leave them be.
• Rust: Brown spots on the underside of the leaves. Usually harmless; cut away badly affected stems.
• Horses: In large amounts ground-ivy can be harmful to horses. Keep it out of horse pastures and hay.

Through the year

• February: First new leaves; the runners start growing again.
• March: First blue flowers. Bumblebee queens visit. Plant.
• April: Full flower. Hairy-footed flower bees and bee-flies are on the wing. Do not mow flowering patches.
• May: Flowering continues. Pull runners out of the border.
• June: Last flowers. Cut or mow the flowering stems short.
• July: Runners grow. Water during long dry spells.
• September: Plant or move rooted runners.
• October: Plant. Give the lawn with ground-ivy a last mow.
• December: Rest. The leaves partly stay green.

Did you know?

• Before hops became common, ground-ivy was used to clear and flavour beer, which is why it was also called alehoof in English.
• Some plants have flowers with both sexes and others only female flowers; the female flowers are clearly smaller.
• Despite its name, ground-ivy is not related to ivy: it belongs to the mint family, like mint and sage.