Threadleaf speedwell
Veronica filiformis · Plantaginaceae
The gardener's calendar
Ideal time to plant threadleaf speedwell: set it out when the soil is neither frozen nor waterlogged, and water generously as it establishes.
ID card
- Foliage
- Evergreen to semi-evergreen depending on climate
- Flowering
- Spring to early summer (April-June)
- Mature size
- 5-10 cm in height, creeping and spreading habit
- Growth
- Fast
- Hardiness
- Hardy down to -15°C
- Origin
- Caucasus and Western Asia
- Soil type
- Well-draining, tolerates poor soils
- Exposure
- Sun to partial shade
Care
Watering
Water moderately during the growing season, keeping the soil slightly moist without waterlogging. Reduce watering in winter. Prefer watering in late afternoon to limit leaf moisture, which can promote fungal diseases.
Exposure and light
Position your threadleaf speedwell in full sun or partial shade for optimal flowering. It tolerates shaded areas but will flower less abundantly. Avoid overly hot and dry exposures in Mediterranean regions.
Pruning and maintenance
Prune after flowering to maintain a compact shape and encourage dense growth. Remove any dead or damaged parts in spring. This creeping plant responds well to light pruning but doesn't require heavy cutting back.
Soil preparation
Prepare well-draining soil lightly enriched with organic matter. Threadleaf speedwell tolerates poor and rocky soils. Improve drainage if your soil retains too much water, particularly in winter.
Feeding
A balanced fertilizer application in spring is generally sufficient. Avoid excess nitrogen, which would promote foliage at the expense of flowering. Naturally poor soils rarely need additional fertilizers.
Diseases and pests
Powdery mildew and root rot can affect the plant in humid conditions. Improve air circulation and reduce leaf moisture. Occasional aphids can be controlled by water spray or neem soap if necessary.
Did you know?
Threadleaf speedwell has become invasive in some regions like Great Britain and North America, where it invades damp lawns thanks to its rapid growth and reproduction by fragmentation. Its accidental introduction as an ornamental plant shows how a small, discreet herb can profoundly alter ecosystems, earning it the unflattering nickname of 'speedwell' or 'plague of the lawn' among our English-speaking neighbours.
Where to buy it
Plant in spring or early autumn, avoiding spells of intense heat. Pick a plant with healthy foliage and roots that are not exposed. Best time: March, April, May, September.
Add this plant to my garden →Plants from the same family
- Ivy-leaved toadflaxCymbalaria muralis
- Spike speedwellVeronica spicata
- Heart-leaf Globe DaisyGlobularia cordifolia
- Talus slope penstemonPenstemon digitalis
- Coral plantRusselia equisetiformis
- Bunchleaf penstemonPenstemon heterophyllus
Tips generated and checked by Viridia — adapt them to your local climate.