Thyme-leaved speedwell (Veronica serpyllifolia) is a member of the plantain family and is a perennial. It can be found in virtually every part of the globe. You’ll find it growing in wet environments, whether in the woods, on a hillside, or in grassy pastures. If you want to keep it out of your yard, regularly mow and water your grass. This will create dense growth, which will limit thyme-leaved speedwell’s ability to thrive.
I. Appearance and Characteristics
Veronica serpyllifolia, the thyme-leaved speedwell or thymeleaf speedwell, is a perennial flowering plant in the plantain family. It is native to Europe, but can be found elsewhere on most continents as an introduced species.
Veronica serpyllifolia L. initially grows low to the ground then will start to grow upright. The flowers are small, white, and have dark purple marks on their petals. The leaves are oval, borne on creeping stems. Roots grow from leaf axils. The prostrate stems bear erect flowering branches up to 20 cm high.
The leaves are opposite on short stalks. The flowers are in racemes with a corolla 6 mm wide. The first leaves of the seedling have no petiole, are hairless, and have a smooth margin. Their stems grow from nodes on the rhizomes, allowing it to grow in thick mats close to the ground. The lower leaves are oval and have smooth margins. The upper leaves are oval shaped but smaller than the lower leaves. The lower leaves have relatively short stalks, while the higher or upper leaves are stalkless (lack petioles).
Flowers have four petals and grow from the leaf axils. The fruits are capsules. The capsules are obcordate or heart shaped, mostly flattened and have a pubescent outer layer with a notched tip.
Veronica serpyllifolia capsules are approximately 2.5-3.5 mm long. Once the capsules are mature, they open to release many small seeds. Their root systems are both fibrous and rhizomatous. The fruit is lined with hairs and the seeds on the inside of the capsule are also flattened. This plant can be hard to spot as it is relatively small and grows in patches which can be covered by grass. They are more noticeable when they bloom. Veronica serpyllifolia reproduces either by dropping its seeds or by rooting stems.
Pollinators of V. serpyllifolia include flies and bees that visit the flowers for nectar. The seeds can be dispersed by attaching onto the wings of birds or the fur of some animals. Veronica serpyllifolia seeds were found in cattle dung, thus cattle or other grazers are likely important dispersers of the plant.
II. How to Grow and Care
Thyme-leaved speedwell (Veronica serpyllifolia) is a member of the plantain family and is a perennial. It can be found in virtually every part of the globe. You’ll find it growing in wet environments, whether in the woods, on a hillside, or in grassy pastures. If you want to keep it out of your yard, regularly mow and water your grass. This will create dense growth, which will limit thyme-leaved speedwell’s ability to thrive.
Sunlight
Thyme-leaved speedwell flourishes under full sun, where it receives unfiltered sunlight for at least 6 hours per day, which is essential for robust growth and optimal health. However, it demonstrates adaptability by tolerating partial sun conditions, which may lead to a slight decrease in vigor and potential delays in flowering or reduced bloom size. With partial sun, thyme-leaved speedwell still manages to sustain itself, though with possibly less dense foliage.
Outdoors, thyme-leaved speedwells should be planted in locations with clear access to sunlight, avoiding overly shaded areas to prevent etiolation. The light exposure influences photosynthesis rates, affecting thyme-leaved speedwell’s overall vitality and resilience.
Temperature
Thyme-leaved speedwell , native to temperate Asia and Northern Europe, prefers a warm growth environment, and is relatively cold-resistant. It is suitable for growing in the temperature range of 15 to 25 ℃. It should be noted that overwatering should be avoided in winter.
Watering
Thyme-leaved speedwell thrives in its native cool temperate zones, where it experiences consistent moisture yet well-drained conditions. This species is known for its preference for moderate humidity and has a balanced approach to water retention. It requires watering every week to maintain its health. Thyme-leaved speedwell typically flourishes outdoors, where the natural rainfall contributes significantly to its growth cycles, making it less dependent on supplemental watering during the rainy season.
Soil
Thyme-leaved speedwell is suitable for growing in fertile, thick, but well-drained sandy soil with an appropriate pH of 5.8 to 7.5. The mixed soil is better and can ensure good permeability. It cannot live in the soil with excessive moisture. In particularly, excessive soil moisture should be avoided in winter. The cultivating soil should be well drained and can be mixed with clay, wood fibers such as bark and coconut bran, and sand at the ratio of 3:2:2:2.
Fertilizing
Thyme-leaved speedwell does not require much fertilizer, so applying a little is fine. After it enters the growth period, it is necessary to apply a small amount of water-soluble compound fertilizer with nitrogen, phosphorus and potassium at the ratio of 20-10-20. In order to promote the flowering, when thyme-leaved speedwell is about to enter the flowering period, it is necessary to apply water-soluble compound fertilizer with nitrogen, phosphorus and potassium at the ratio of 10-30-20, generally 10 to 15 days before the flowering period.
Fertilizer can be reduced after early fall, as its growth speed begins to slow. Fertilization is not required in the recovery period because the nutrient absorbing ability of the injured root system is weak. Too much fertilizer can lead to an injured root system or slow growth.
Planting Instructions
Thyme-leaved speedwell can be propagated by its seeds, and the seeds can be sown in flowerpots or gardens. If sown in a flowerpot, it can be done in early spring. Fill the flowerpot with cultivable soil, fill a little water in a shallow pan, and place the pan at the bottom of the flowerpot, so that the water permeates the soil thoroughly and makes it moist. Spread the seeds on the soil, cover with another layer of fine soil, and finally cover the flowerpot with cling film or a glass plate. The seeds will germinate in about 20 days at 20 °C. When the seedlings grow up, you can transplant them where you want.
If sown in a garden, it should be done later, from mid-spring to late spring. After sowing, water it once and cover the surface with plastic film. The seeds can germinate in about 30 days. It is best to have appropriate shade after sowing to avoid sun exposure.
Pruning
The withered flowers of thyme-leaved speedwell will not fall off from the flowering branches automatically, but still stay on the flowering branches. It is recommended that remnant flowers be removed in time to keep the plant look good, as well as to reduce unnecessary nutrient consumption, promoting the growth of underground parts.
Pruning should be done in the morning on sunny and dry days. When pruning, cut the flowering branch at the base where the last flower is in close proximity to it. Mastering the time of pruning can regulate the flowering period. In general, thyme-leaved speedwell will bloom again in 20 days after pruning. After winter, when the ground temperature rises to above 0 ℃, almost early spring, the withered and yellowed parts overground should be pruned, so that it begins its growth in the new year.
Propagation
The ideal propagation season for thyme-leaved speedwell is in Spring and Summer through stem cuttings. Propagation moderately easy, with successful signs being new leaf growth. Keep cuttings moist and in indirect sunlight.
Transplanting
Autumn, most preferably early autumn, is the ideal season for transplanting thyme-leaved speedwell, as it allows strong root development before winter. Thyme-leaved speedwell thrives in well-drained soil, in spots with full sun to partial shade. Ensure ample spacing for healthy growth and remember, patience yields the most attractive results!
III. Uses and Benefits
Often considered a weed, thyme-leaved speedwell is a small yet handsome wildflower. The plant grows in a trailing, mat-forming habit, making it suitable to include in a native, wild-type groundcover. Thyme-leaved speedwell is also tolerant of light foot traffic, so it can be used in alternative lawn mixes. However, keep in mind that this tough plant has invasive tendencies and can be a pest in turf lawns.
IV. Harvesting and Storage
If 20%-30% flowers on each spica of thyme-leaved speedwell bloom, the spica can be cut off for appreciation. For the cut spica, the vase life is about 8 to 14 days. When harvesting, sharp garden shears are recommended to cut to the base of the flowering branches, and then prune the flowering branches at an angle of 45° to increase the water absorption area. Put the cut branches in a vase with clean water in time to avoid water loss.
V. How to Control
Veronica serpyllifolia grows in patches and is commonly recognized as a weed of turf grass. Ways to remove V. serpyllifolia from lawns are by mowing and watering and fertilizing lawns properly, this hinders the weeds ability to compete. The use of herbicide is recommended for the complete removal of this species from a yard or a lawn. Picking the weed and pulling the roots out can work but this risks the further dispersal of seeds on the lawn. One study showed that wiping herbicides onto the plant rather than spraying it helps to better remove of the species. It stated that wiping method worked better and the spray on method caused harm to other grasses surrounding the weeds.