Gentian speedwell

Gentian speedwell: how do you recognise it?

Habit

Low perennial 30–40 cm tall and 40 cm wide, forming a mat of rosettes with upright flower spikes.

Leaves

Rosettes of glossy, dark green, lance-shaped leaves 5–10 cm long; semi-evergreen in mild winters.

Flowers

Small flowers in loose spikes 20–40 cm long, from April to June.

Colour

Pale blue to almost white, with fine, darker blue veins.

Roots

Creeping runners that slowly widen the mat.

Flowering: April–June · Plants: March–April and September–October · Pruning: March and July

Why grow it?

• Flowers as early as April–June, when many other perennials are not yet in bloom.
• Glossy, almost evergreen rosettes that stay attractive outside the flowering season.
• A neat, low ground cover for the front of the border.
• Bees and other insects visit the flowers.
• Very hardy and low maintenance.

Gentian speedwell: where does it grow best?

• Sun to partial shade: in full sun it flowers richly, in partial shade the foliage stays fresher.
• Humus-rich, well-drained soil: sand, loam or clay with compost, neutral to acid or chalky.
• Normal soil that neither dries out nor stays too wet.
• Allow 40 cm per plant, or 25–30 cm for a quickly closing mat.

Light

Sun and partial shade

Soil type

Loam or clay

Acidity

Not fussy

Moisture

Normal

Size

0.4 m tall, 0.4 m wide

Hardiness

Hardy (to -30 °C)

Goes well with

• Hardy geranium: Flowers for longer above the low mat.
• Lady’s mantle: Soft, frothy yellow clouds next to the fresh blue.
• Primula: Flowers at the same time in partial shade.
• Daffodils: Early bulbs come up through the mat.

Gentian speedwell: 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 neither frozen nor waterlogged.
2. Dig a hole as wide as the root ball and mix in a spade of compost.
3. Set the plant at the same depth as in its pot and firm the soil well.
4. Space plants 30–40 cm apart; in groups they look their best.
5. Water in straight away and spread a thin layer of leaf-compost mulch around the plant.

Care

Water

Keep the soil evenly slightly moist, especially in the first year and in dry summers.

Feeding

A spade of compost or organic fertiliser in spring is enough.

Mulching

A thin layer of leaf compost keeps the soil cool; do not cover the rosettes.

Spent flowers

Cut the spikes back after flowering: it keeps the mat compact and gives fresh rosettes.

Dividing

Divide the mat every 3–4 years when the centre goes bare.

Tip: Divide the mats after a few years and replant the young, rooted pieces; this keeps the plant vigorous. It looks lovely as a low edging along a path.

Gentian speedwell: when to prune it?

Pruning months: March and July.

When: After flowering in July, with a tidy-up in March.

How:

• After flowering, cut the faded spikes off just above the rosettes.
• In March, remove damaged or brown leaves from the winter.
• Trim back runners that have strayed too far if the mat gets too large.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Division

In spring or in September: cut the mat with a spade into pieces with roots and rosettes, and replant straight away.

Cuttings

In May–June take cuttings of 5–8 cm from non-flowering shoots in moist cutting compost; they root within a few weeks.

Gentian speedwell: how does it get through the winter?

Hardy to −30 °C.

• Fully hardy, to about −30 °C: no protection is needed in Flanders.
• The rosettes usually stay green in mild winters; cut off brown or damaged leaves in March.
• Wet winters on heavy clay are the main risk: provide good drainage and it will survive easily.
• In a pot: use well-drained soil and do not stand the pot in a wet corner.

Diseases and pests

• Slugs: Nibbled rosettes in spring. Collect them in the evening and scatter coarse bark around the plant.
• Powdery mildew: White powder on the leaves in damp, muggy weather. Allow space and remove affected leaves.
• Root rot: Limp, brown rosettes in wet soil, especially in winter. Plant in a dry spot or improve the drainage.
• Bare mat: The centre opens up after a few years. Divide the mat in spring and replant the young pieces.

Through the year

• March: Tidy dead foliage. Plant. Divide.
• April: Flowering begins. Plant.
• May: Full flower. Take cuttings.
• June: Last flowers. Take cuttings.
• July: Cut back faded spikes.
• August: Water in dry weather.
• September: Plant or divide.
• October: Plant.
• November: Rest.
• December: Rest.

Good for wildlife

Bees

Nectar and pollen for honeybees and wild bees.

Did you know?

• The species name gentianoides means ‘gentian-like’, after the blue flowers that recall a gentian.
• It is one of the earliest-flowering speedwells in the garden.
• The rosettes often stay green in mild winters, so the plant covers the ground even in that season.