Verbena bonariensis

Common name: Purple Top Vervain / Argentinian Vervain

Description: Verbena bonariensis is one of the most popular and widely planted garden perennials of the past two decades — and with very good reason. Its tall, wiry, branching stems rise to 1.5m or more, topped with clusters of vivid violet-purple flowers from midsummer to late autumn, creating an airy, transparent effect in the border that allows views through to plants behind. It self-seeds freely but rarely invasively, naturalising into a border in a very pleasing, informal way. Its long flowering season, drought tolerance, minimal maintenance, and exceptional value for butterflies and other pollinators make it virtually indispensable in a wildlife-friendly garden.

Other benefits: exceptionally long flowering season; airy transparent habit allows views through the border; self-seeds to naturalise; minimal maintenance; outstanding wildlife value

Wildlife attraction: butterflies, bees, and other pollinating insects — one of the very best garden plants for butterflies

Height & spread (approx.) at 10 years: 1.2–1.8m x 45cm

Position: full sun; borders, gravel gardens, and naturalistic plantings; self-seeds into gravel and paving cracks

Soil pH: neutral (pH 6.0–7.0); well-drained, moderately fertile soil; tolerates clay if not waterlogged

Moisture: low to moderate; drought tolerant once established; avoid waterlogging

Winter hardiness: hardy to approximately -10°C; self-seeds freely so even if plants are lost, new seedlings appear