Origin
Veronicastrum serpyllifolium (L.) Fourr. ssp. humifusum (Dickson) W.A. Weber is native to North America. It can be found growing throughout most of the continental United States, from the eastern seaboard to the Rocky Mountains.
Common Names
This plant is commonly known as creeping speedwell or thyme-leaf speedwell due to its creeping habit and thyme-like foliage. It is also sometimes referred to as wood sage or American speedwell.
Uses
Creeping speedwell has historically been used in traditional medicine for its astringent and diuretic properties. It was often brewed into a tea to help treat urinary tract infections and bladder inflammation. Additionally, the plant was sometimes crushed and used as a poultice to treat skin irritations and burns. In gardens, creeping speedwell is sometimes used as a ground cover or in rock gardens due to its low-growing habit and attractive small blue flowers. It is also attractive to pollinators, making it a popular choice for backyard wildlife gardens.
General Appearance
Creeping speedwell typically grows to be between four and eight inches tall and spreads through runners to form a dense mat of foliage. The plant has small, narrow leaves that resemble thyme leaves and small, bright blue flowers that bloom in the late spring or early summer. The flowers are arranged in dense spikes that rise slightly above the foliage. Creeping speedwell prefers full sun to partial shade and moist, well-drained soil.
Light Requirements
Veronicastrum serpyllifolium ssp. humifusum prefers partial shade to full sun exposure for optimal growth. It can tolerate a range of light conditions but performs best when provided with ample light to photosynthesize efficiently.
Temperature Requirements
This plant thrives in well-draining soils that retain adequate moisture, but do not become waterlogged. It is hardy to USDA zones 3-8 and can withstand temperatures as low as -40°F (-40°C) during the winter months. In the summer, it prefers temperatures between 60°F (15°C) and 80°F (27°C).
Soil Requirements
The soil for Veronicastrum serpyllifolium ssp. humifusum should be moist, well-draining, and rich in organic matter. It prefers soils with a slightly acidic to neutral pH, ranging from 5.5 to 7.5. Incorporating compost into the soil before planting will improve soil fertility, drainage, and water retention.
Cultivation Method:
Veronicastrum serpyllifolium ssp. humifusum is a herbaceous perennial plant that prefers well-drained soil, partial shade to full sun, and a slightly acidic to neutral pH level of the soil. It is best propagated in the late spring or early summer through seed or division. Planting should be done in holes that are about twice the width and depth of the root ball. This plant does not tolerate disturbance, so be sure to handle it with care when planting or moving it.
Watering Needs:
Veronicastrum serpyllifolium ssp. humifusum requires adequate soil moisture but can be sensitive to overwatering. Watering should be done deeply and infrequently, allowing the soil to dry slightly between watering. In prolonged dry conditions, additional watering may be necessary, but regular monitoring of the soil moisture level is crucial.
Fertilization:
Veronicastrum serpyllifolium ssp. humifusum does not need excessive fertilization and prefers organic fertilizers. Fertilizers should be applied in the spring before new growth occurs. Applying a slow-release granular fertilizer that is high in nitrogen can promote lush foliage growth while a fertilizer that is high in phosphorus can encourage abundant flowering.
Pruning:
Veronicastrum serpyllifolium ssp. humifusum does not require regular pruning but may benefit from deadheading spent flowers to encourage continued blooming. The plant can be pruned in the late fall or early spring to remove any damaged or diseased stems and to control the plant's shape. It is essential to use clean, sterilized pruning tools to avoid transmitting any pathogens.
Propagation of Veronicastrum serpyllifolium ssp. humifusum
Veronicastrum serpyllifolium ssp. humifusum can be propagated through both vegetative and sexual reproduction.
Vegetative Propagation
The most commonly used vegetative propagation method for Veronicastrum serpyllifolium ssp. humifusum is division. This method involves separating the plant's roots and replanting them in a new location. The best time to divide Veronicastrum serpyllifolium ssp. humifusum is during the plant's dormancy, either in the early spring or late fall. This method is best used when a gardener wants to produce multiple identical offspring from one parent plant.
Sexual Propagation
Veronicastrum serpyllifolium ssp. humifusum can also be propagated through sexual reproduction. This method involves collecting seed pods from a mature plant and sowing them in a prepared bed. The seeds should be sown in the fall in an area with well-draining soil that receives partial or full sun. The seeds will then germinate in the spring and should be thinned to allow more space for growth. Sexual reproduction is best used when a gardener wants to create genetic diversity in their garden or when a gardener wants to propagate a large number of plants at one time.
Disease Management
Veronicastrum serpyllifolium ssp. humifusum is susceptible to fungal diseases such as powdery mildew, leaf spot, and rust. To manage these diseases, it is essential to remove and destroy any infected plant parts promptly. Regularly inspect the plants to detect any signs of disease early and apply fungicides as necessary. Fungicides that contain copper or sulfur can be effective against powdery mildew and rust disease. However, it is important to follow the instructions on the label carefully to avoid overuse of the fungicide.
Pest Management
Veronicastrum serpyllifolium ssp. humifusum is usually not greatly affected by pests. However, aphids, spider mites, and whiteflies might attack the plant. Aphids can be controlled by spraying the affected plants with water or insecticidal soap. For the spider mites, earlier detection is crucial, so regular inspection should be done. An effective method of managing spider mites is to spray the affected plants with neem oil or insecticidal soap. Finally, remove plant debris and keep the planting area free of weeds or other pests that can serve as alternative hosts for the pests.
