Large self-heal

Large self-heal: how do you recognise it?

Habit

Low, mat-forming plant about 25 cm tall and 40 cm wide, with creeping stems that root where they touch the ground.

Foliage

Oval, 3–8 cm, opposite on square stems, dark green and slightly hairy; largely evergreen in mild winters.

Flowers

Dense, square spikes of 3–5 cm with large, two-lipped flowers, from June to August.

Colour

Usually violet to purple. There are also pink, lilac and white cultivars, such as ‘Pink Loveliness’ and ‘White Loveliness’.

Roots

Fibrous and shallow, with runners that root easily.

Flowering: June–August · Plants: March–May and September–October · Pruning: March and August

Why grow it?

• Flowers for a long time, from June to August, with large purple flower spikes.
• Mat-forming ground cover: keeps weeds down and fills bare spots.
• Bumblebees, bees and butterflies are drawn to the flowers.
• Tolerates sun and half shade and can take a dry spell.
• Fully hardy to about −30 °C and stays largely green in mild winters.
• Little work: a short trim after flowering is enough.

Large self-heal: where does it grow best?

• Sun or half shade; in full sun it flowers most freely.
• Well-drained soil: sand, loam or clay, neutral to chalky.
• Dry to moderately moist; it dislikes wet feet in winter.
• Ideal at the edge of a border, along a path or in a rock garden.
• Allow 30–40 cm between plants; they soon close the gaps.

Light

Sun and partial shade

Soil type

Sand, loam or clay

Acidity

Neutral or chalky

Moisture

Dry or normal

Size

0.25 m tall, 0.4 m wide

Hardiness

Hardy (to -30 °C)

Goes well with

• Hardy geranium: Blue and purple flowers that bloom together and also fill the front of the border.
• Lady’s mantle: Yellow flowers and soft foliage next to the purple spikes.
• Sage: Purple spikes on upright stems above the low mat.
• Yarrow: Brings yellow or pink flat heads in the same sunny, well-drained soil.
• Lavender: The same sun and dry soil, with grey foliage and purple flowers.

Large self-heal: when and how to plant it?

Plant in March–May and September–October.

1. Plant in March–May or in September–October, when the soil is neither frozen nor too wet.
2. Dig a hole as wide as the root ball and mix in a little compost.
3. Set the plant at the same depth as in its pot and firm the soil well.
4. Leave 30–40 cm between plants; for a faster carpet, plant closer.
5. Water in generously straight away, even if it is raining.
6. Keep the soil lightly moist in the first year until the plant is established.

Care

Water

In the first year water weekly in dry weather. After that it is rarely needed, only in a long dry summer.

Feeding

A thin layer of compost in spring. Too much feeding gives soft foliage that is prone to disease.

Mulching

Not really needed: the plant covers the soil itself. Add a thin layer of compost, but do not bury the plant.

Spent flowers

Cut off the faded spikes to prevent self-seeding and sometimes get a second flush.

Keeping in check

Cut off runners that stray too far with a spade, especially along the lawn and next to weaker neighbours.

Tip: After flowering, cut off the faded spikes and sever runners that stray too far with a spade: that way it stays a neat edging and does not seed everywhere.

Large self-heal: when to prune it?

Pruning months: March and August.

When: In August after flowering and in March as a tidy-up.

How:

• Cut off faded spikes in August, just above the foliage.
• If the plant has become untidy or patchy, cut it back after flowering to about 5 cm above the ground: fresh foliage will follow.
• In March remove old, brown leaves and cut off runners that stray too far.

Caution: It spreads by runners and by self-seeding. In small borders or next to weak plants, keep it in check by cutting off the spikes and severing the runners.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Division

In March–April or September–October: cut a piece of the mat with roots or divide a clump and replant the pieces straight away elsewhere. This is the quickest and easiest method.

Seed

Sow in spring or autumn in a tray of seed compost, barely covering the seed. Keep the tray lightly moist in a bright spot; seedlings appear after a few weeks. Cultivars do not always come true from seed.

Large self-heal: how does it get through the winter?

Hardy to −30 °C.

• Fully hardy, to about −30 °C: no protection is needed in Belgian winters.
• The foliage stays largely green in mild winters; in severe winters it partly dies back and the plant grows again in spring.
• Make sure water can drain away in winter: cold, wet soil causes rot.

Diseases and pests

• Powdery mildew: White powder on the leaves, especially in dry, stuffy summers. Water at the base, leave space between plants and cut off affected leaves.
• Slugs: Holes in the young leaves in spring. Collect them in the evening and clear hiding places.
• Spreading: The plant sends out runners and self-seeds. Cut off faded spikes and sever the runners with a spade.
• Rot in wet soil: Brown, soft patches in the mat after a wet winter. Provide well-drained soil and remove affected parts.

Through the year

• March: Plant or divide. Cut off old leaves. Give compost.
• April: Plant. Check the runners.
• May: Plant. Water in a dry spring.
• June: Flowering begins.
• July: Full flower. Water in a long drought.
• August: Cut off faded spikes, or cut the whole plant back.
• September: Plant or divide.
• October: Plant. Tidy untidy foliage.

Good for wildlife

Bees

Nectar and pollen for honeybees and wild bees.

Butterflies

Nectar for butterflies.

Did you know?

• The flowers are much bigger than those of the common self-heal (Prunella vulgaris), a small plant of lawns and road verges.
• As in many members of the mint family, the stems are square.
• The two-lipped flowers are mainly visited by bumblebees and bees.