Purple Porterweed

Binomial name

Stachytarpheta frantzii

Common names

Frantzia’s Verbena, Blue Vervain

Description

Stachytarpheta frantzii, also known as Frantzia’s Verbena or Blue Vervain, is a hardy, upright shrub with long spikes of vibrant blue to purple flowers. It’s an attractive addition to tropical and subtropical gardens, often used for borders, hedges, or as a pollinator-friendly plant. The plant features lance-shaped leaves that provide a contrasting backdrop to its striking, tubular flowers. Stachytarpheta frantzii is known for its fast growth and resilience, making it a low-maintenance option for gardeners seeking both beauty and functionality.

Light requirements

Stachytarpheta frantzii does best in full sun, where it will produce the most flowers and grow the most vigorously. It thrives in areas that receive at least 6 hours of direct sunlight daily. While it can tolerate light shade, flowering will be less abundant in shaded locations. A sunny spot ensures lush growth and an impressive flower display.

Soil preferences, including pH and drainage

This plant prefers well-draining, slightly acidic to neutral soil with a pH range of 6.0 to 7.0. It grows best in sandy or loamy soils but is relatively adaptable to different soil types, provided they drain well. Good drainage is crucial to avoid waterlogged roots, which can lead to disease. Stachytarpheta frantzii can thrive in less fertile soils, making it a great choice for a variety of garden conditions.

Water needs

Stachytarpheta frantzii has moderate water needs. It prefers regular watering to keep the soil consistently moist, but it’s tolerant of short dry spells once established. Be sure to allow the soil to dry out slightly between waterings to avoid root rot. In cooler months or when the plant is not actively growing, water less frequently but ensure it doesn't completely dry out. This plant is relatively drought-tolerant once it’s well-established.