Pyrenean speedwell: complete guide

Overview

Veronica nummularia, commonly known as Pyrenean speedwell or coinleaf speedwell, is a low-growing, creeping perennial belonging to the plantain family (Plantaginaceae). The species was described in 1773 by the French botanist Gouan from specimens collected in the Pyrenees. The species name nummularia derives from the Latin nummulus meaning "small coin", a reference to the small, round to kidney-shaped leaves that somewhat resemble coins.

The natural distribution is confined to a relatively small area encompassing the Pyrenees and the adjacent Cantabrian mountains in northern Spain. The plant grows on rocky, moist subalpine and alpine meadows and stream margins, typically at altitudes between 1,400 and 2,500 metres above sea level. Here it forms part of the characteristic high-mountain flora alongside other rock plants such as Saxifraga, Dryas, and Gentiana.

In the garden, Veronica nummularia is a gem for the rock garden, alpine raised bed, or stone trough. The plant forms compact, creeping mats of glossy dark green foliage from which numerous bright blue flowers emerge in summer. The combination of small scale, elegant blooms, and a modest, non-invasive habit makes it a favourite among enthusiasts of alpine plants and miniature garden design.

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Several synonyms have been described over the years, including Veronica irregularis (Lapeyr.) and Cardia nummularia (Gouan) Dulac, but the accepted name is Veronica nummularia Gouan. The species belongs to a group of small-leaved, mat-forming speedwells that are characteristic of the Pyrenean flora.

Appearance & bloom cycle

Veronica nummularia forms low, bushy mats 5-15 cm tall with a spread that can reach 20-30 cm over several years. The stems are prostrate to ascending, finely hairy, and light brown to greenish-brown in colour. They root readily where they touch the soil, allowing the plant to spread slowly across the growing surface.

The leaves are noticeably small and compact: 5-12 mm across, almost circular to kidney-shaped, with a finely toothed margin. They are fleshier and glossier than those of most other speedwells, giving the plant a fresh, moisture-rich appearance. The colour is dark green, occasionally taking on a slightly bronzed hue in strong sunshine. In mild climates the foliage remains softly green through winter; in harder conditions the leaves die back and new shoots emerge from the rootstock in early spring.

The flowers appear in July and August, sometimes extending into September. Each bloom is small - 6-8 mm across - but they are numerous and a clear, vivid blue, typically with darker blue veins and a small white eye at the centre. The inflorescence is a short, loose raceme bearing 5-12 flowers per stem. Although the individual flowers are tiny, the sheer number of flowering stems makes the overall display quite striking against the dark foliage.

After flowering, small heart-shaped seed capsules develop. The plant self-seeds lightly in favourable conditions on open ground or in rock crevices, but rarely forms troublesome colonies.

Ideal location

Veronica nummularia is a plant of cool, moist mountain environments and requires a garden position that replicates these conditions as closely as possible. The plant prefers partial to light shade: too much direct afternoon sun dries it out too quickly and can scorch the leaves in warm summers. A position that receives morning sun and afternoon shade is ideal.

Good sites include the north- or northeast-facing side of a rock garden, the base of a rock outcrop, the edge of a stone trough, or a moist crevice in a dry stone wall. In upland or higher-altitude gardens it also does well in a more open but not excessively dry position. In lowland gardens extra attention to moisture and shade is needed to keep the plant comfortable during warm summers.

The plant does not tolerate prolonged drought: when moisture is lacking the leaves roll inward and become limp; in sustained dry conditions the plant dies back. In urban gardens prone to summer heat stress, this species is challenging to grow unless you can provide a cool, shaded position with moisture-retentive soil. In cooler, moister climates - such as the coastal areas of Belgium or the western Netherlands - it performs considerably better.

Combine Veronica nummularia with other alpine plants sharing similar site requirements: Saxifraga species, small Primulas, Dryas octopetala, or Gentiana acaulis are excellent companions with the same preference for cool, moist conditions.

Soil requirements

The ideal soil for Veronica nummularia is free-draining yet moisture-retentive, mineral-rich, and mildly acidic to neutral. In its natural Pyrenean habitat the plant grows on rocky mountain meadows and alongside mountain streams, where the soil offers a combination of rapid drainage and a continuous supply of meltwater or rainwater. This apparently contradictory profile - free-draining yet consistently moist - is the hallmark of a good alpine soil mix.

In the garden, achieve this by preparing a blend of equal parts loam-based potting compost, coarse sharp sand, and small grit or stone chips. A pH of 5.5 to 7.0 is optimal. Lime in the soil is tolerated but strong alkalinity is less favourable. Fresh manure or heavily nitrogen-rich compost should be avoided: too much fertility produces lush but soft growth that suppresses flowering and increases the risk of fungal problems.

In a stone trough, an alpine mix works well: fill the trough to two-thirds with a blend of equal parts stone grit or gravel, sharp sand, and good garden soil, and dress the top layer with fine stone grit. This improves drainage and prevents the leaf bases from rotting in persistently moist conditions. Always ensure drainage holes are present at the base of the trough.

A thin layer of gravel or crushed slate 1-2 cm deep around the plant helps maintain soil moisture, suppress weeds, and protect the plant base.

Watering

Veronica nummularia needs consistent moisture and is by no means drought tolerant. In its natural range it benefits from meltwater, regular precipitation, and the high humidity of the mountain climate. In the garden, replicating this as closely as possible is essential.

In dry spells: water as soon as the top layer of soil begins to dry slightly - typically every two to four days during warm, dry weather. Never allow the plant to dry out completely for extended periods. Use a watering can with a fine rose applied close to the base of the plant; avoid leaving water sitting on the foliage for long periods, as this can encourage fungal problems.

Drip irrigation is ideal: it keeps the soil consistently and lightly moist without wetting the foliage. In warm summers with temperatures above 25 degrees Celsius, the plant may take on a slightly wilted appearance during the hottest part of the day - this is normal and it will recover once conditions cool.

In winter, very little watering is needed: the plant is largely dormant and regular rainfall is sufficient. Take care to avoid waterlogging around the roots during frost periods - frozen wet soil can damage the root system. On a free-draining substrate this risk is minimal.

In a stone trough, check moisture levels by pressing a finger 2-3 cm into the substrate: if it feels noticeably moist, no watering is needed; if it feels dry, it is time to water. Troughs can dry out faster than borders in summer, making daily checks advisable during hot weather.

Pruning

Veronica nummularia requires minimal pruning. Remove the spent flower heads after blooming - in September or early October - using small, sharp scissors or simply by pinching them off. This keeps the plant tidy and prevents excessive self-seeding.

In early spring, once new growth becomes visible (usually in March or April), remove any dead or frost-damaged stems. Do not cut back the mat drastically: this is a slow-growing plant that does not respond well to hard pruning. A light tidy-up removing loose, dead, or overly long stems is all that is needed.

If after several years the plant shows poor flowering or begins to die out in the centre, lift it carefully in early spring, divide it into smaller rosettes, and replant in refreshed soil. This rejuvenation encourages strong new growth and renewed flowering.

Regular weeding around the plant is important: Veronica nummularia grows slowly and is easily overwhelmed by fast-growing weeds or overly aggressive neighbouring plants.

Maintenance calendar

January - February: Minimal care. Check that the plant is not sitting in waterlogged soil during frost. In hard winters the foliage may largely die back - this is normal.

March - April: Start of the growing season. Remove dead or frost-damaged stems. Check soil moisture levels. New plants or divisions can be planted once the ground has thawed.

May - June: Active growing period. Water regularly in dry weather. Remove weeds. Check that the soil stays adequately moist, especially during warm spells.

July - August: Flowering period. Enjoy the bright blue flowers. Water regularly - never allow the plant to dry out. During very hot spells above 28 degrees, consider temporary shade provided by a fine mesh screen.

September - October: Remove spent flower heads after the bloom has finished. Check drainage around the plant before winter. Gradually reduce watering as temperatures drop.

November - December: Virtually no maintenance. Regular rainfall is sufficient. Ensure there is no waterlogging around the roots during frost periods.

Winter hardiness

Veronica nummularia is reliably cold hardy, as would be expected for a plant native to the Pyrenees where temperatures regularly fall to -15 degrees Celsius or below in winter. In garden cultivation across the Netherlands and Belgium (USDA zones 5-7), the plant reliably survives even hard winters with temperatures down to -15 degrees, provided the site drains well.

The foliage largely dies back in moderate to hard frosts but the rootstock remains alive and sends up new shoots in spring. In mild coastal climates the leaves may remain partially green throughout winter. The greatest winter threat is not cold itself but frozen wet soil suffocating the roots. On a free-draining, mineral-rich substrate, winter protection is almost never needed.

In containers or stone troughs extra caution is warranted: a small trough can freeze solid in a hard winter, which is fatal for the roots. Move troughs to an unheated but frost-free shed or cool greenhouse during severe cold spells, or wrap them in a layer of horticultural fleece.

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Companion plants

Veronica nummularia pairs beautifully with other alpine and rock garden plants sharing similar requirements - moist but free-draining, cool, and not excessively sunny. Good companions include:

• Saxifraga (Saxifrage) - the most natural companion: similar scale, similar preference for rocky, well-drained substrate. The white or yellow Saxifraga flowers bloom slightly earlier than Veronica and extend the season of interest in the rock bed.
• Primula farinosa (Bird's eye primrose) - small pink flowers in spring, followed by the blue summer flowers of Veronica: a pleasing sequence of colours across the seasons.
• Gentiana acaulis (Stemless gentian) - deep trumpet-shaped blue flowers in spring; requires similarly moist, mineral-rich soil and cool conditions.
• Dryas octopetala (Mountain avens) - low-growing ground cover with white flowers and delicate feathery leaves, forming a fine contrast to the rounded leaves of Veronica nummularia.
• Phlox subulata (Moss phlox) - early-season flowering ground cover that fills the spaces between rocks; the purple or pink flowers combine well with the summer blue of the speedwell.
• Thymus (Thyme) - aromatic, low-growing thyme species thrive on similar stony substrates and make good neighbours for Veronica nummularia in a rock garden with mixed aspect.

Allow a spacing of 15-20 cm between Veronica nummularia and small neighbours, giving it enough room to form its mat gradually without being crowded out. Visit [gardenworld.app](https://gardenworld.app/en/blog) for more alpine planting combinations and rock garden design ideas.

Conclusion

Veronica nummularia is a gem for the alpine plant enthusiast and rock garden designer. This small, unassuming plant from the Pyrenees produces bright blue flowers in summer that create a refreshing contrast against its compact, glossy foliage. It asks for thoughtful placement and reliable moisture, but rewards the gardener who provides these with a graceful, season-after-season display. Whether you are designing a stone trough, an alpine border, or a rock garden feature, this miniature speedwell is well worth seeking out and growing.