How to Grow Verbena Bonariensis for Pollinators: When to Plant, Best Varieties & Care

Intro for Verbena Bonariensis

Verbena bonariensis, commonly known as tall verbena or purpletop vervain, is a graceful perennial that acts as a pollinator magnet in any garden. With its slender, wiry stems reaching 3-4 feet (90-120 cm) tall and topped with clusters of small purple flowers, this airy plant creates a floating effect above neighboring plants. Native to South America, it has become a favorite in cottage gardens and naturalistic plantings worldwide. Verbena bonariensis offers exceptional value for wildlife, attracting bees, butterflies, and hoverflies throughout its long flowering season from summer until the first frosts. Drought-tolerant once established and adaptable to various soil types, this low-maintenance plant is perfect for both novice and experienced gardeners looking to support pollinators.

When to plant Verbena Bonariensis

Verbena bonariensis is best planted when soil temperatures have warmed to at least 15°C (60°F). In most temperate regions, this means waiting until all danger of frost has passed in spring. The plant is frost-tender when young but becomes more resilient once established. In cooler climates (UK, Northern US zones 4-6), wait until late spring when nighttime temperatures consistently stay above 7°C (45°F). In warmer regions (US zones 7-10, Mediterranean areas), you can plant earlier in spring or even in autumn, allowing plants to establish before summer heat arrives. Seeds require warm soil to germinate, so indoor starting is recommended in cooler climates.

Best time to plant Verbena Bonariensis

For cool temperate regions (UK, Northern US), the optimal planting window is mid-May to early June for transplants, or start seeds indoors 8-10 weeks before your last frost date. For direct sowing, wait until late May when soil has thoroughly warmed. In warm temperate regions (Southern US, Mediterranean), plant from March to May or September to October, avoiding the intense summer heat for new plantings. For tropical or subtropical areas, autumn planting (March-May in Southern Hemisphere, September-November in Northern Hemisphere) gives plants time to establish before the following summer.

Best Verbena Bonariensis varieties to grow

• Verbena bonariensis – The species type with tall, airy stems and vibrant purple flower clusters that are irresistible to butterflies.
• ‘Lollipop’ – A compact variety reaching only 60-75 cm (24-30 inches), perfect for smaller gardens or container growing.
• ‘Buenos Aires’ – Features larger flower clusters and more vigorous growth, making it an exceptional pollinator attractor.
• ‘Meteor Shower’ – A newer, more compact cultivar with a branching habit and deep purple blooms on 30-60 cm (12-24 inch) stems.
• ‘Cloud Nine’ – Selected for its particularly large, lavender-purple flower heads that draw in an impressive variety of pollinators.
• ‘Bampton’ – A UK selection known for better cold hardiness, making it suitable for northern gardens.
• ‘Silver Anne’ – Features attractive silvery foliage that contrasts beautifully with the purple flowers.

How to plant Verbena Bonariensis

Materials needed:

• Verbena bonariensis seeds or young plants
• Well-draining potting mix or garden soil
• Compost or well-rotted manure
• Garden fork or tiller
• Watering can with fine rose attachment
• Garden trowel
• Plant labels

Step-by-step planting:

1. Select a site that receives full sun (at least 6 hours daily) with well-draining soil.
2. Prepare the soil by removing weeds and incorporating compost to improve drainage and fertility.
3. For transplants, dig holes slightly larger than the root ball, spacing plants 30-45 cm (12-18 inches) apart.
4. If direct sowing seeds, scatter them thinly on the surface of prepared soil and press lightly – do not cover as they need light to germinate.
5. For transplants, place the plant in the hole at the same depth it was growing in its container.
6. Backfill with soil, firming gently around the roots to eliminate air pockets.
7. Water thoroughly but gently to settle the soil around roots or seeds.
8. For seeds, keep the soil consistently moist until germination occurs (typically 14-21 days).
9. Apply a thin layer of fine mulch around plants, keeping it away from stems to prevent rot.
10. Label your plantings to identify them as they grow.

How to grow Verbena Bonariensis

Verbena bonariensis thrives in full sun positions, needing at least 6 hours of direct sunlight daily for optimal flowering. In very hot climates, light afternoon shade can be beneficial. Water newly planted verbena regularly until established, then reduce to weekly deep watering during dry periods. Once established, these plants are quite drought-tolerant and prefer soil on the drier side. Fertilizing should be minimal – a light application of balanced, slow-release fertilizer in spring is sufficient; over-fertilizing produces lush foliage at the expense of flowers.

Mulch around plants to suppress weeds and retain soil moisture, keeping the mulch a few centimeters away from stems. Deadheading spent flowers encourages continued blooming, though many gardeners leave the seedheads for winter interest and self-seeding. Staking is rarely necessary as the wiry stems are surprisingly strong, but in very exposed sites, discrete support may help. For container growing, use a pot at least 30 cm (12 inches) deep with excellent drainage, and consider the compact varieties like ‘Lollipop’ or ‘Meteor Shower’.

Caring for Verbena Bonariensis

Ongoing care for verbena bonariensis is minimal. In late winter or early spring, cut back the previous year’s stems to about 15-20 cm (6-8 inches) from the ground to encourage fresh growth. Watch for powdery mildew in humid conditions, which appears as a white powder on leaves – improve air circulation by thinning plants and avoid overhead watering. Spider mites can be problematic during hot, dry spells – a strong spray of water on the undersides of leaves can dislodge them, or use insecticidal soap for severe infestations.

Verbena bonariensis rarely suffers from serious pest or disease issues when grown in appropriate conditions. For overwintering in colder regions (zones 5-6), apply a thick mulch around the crown after cutting back in autumn. The plant often self-seeds freely, so remove unwanted seedlings in spring if they appear in undesired locations. Flowers can be harvested for arrangements when the flower clusters are fully open but before seeds form, cutting stems in the morning when plants are well-hydrated.

Understanding bolting in Verbena Bonariensis

Unlike many garden plants, bolting is not a concern with verbena bonariensis as it’s grown specifically for its flowering stems. The tall, slender stems topped with flowers are the plant’s natural growth habit rather than a stress response. The plant naturally flowers from summer through autumn, with flowering triggered by day length and warm temperatures. If plants seem to be producing fewer flowers, this is typically due to insufficient sunlight, over-fertilization (especially with nitrogen-rich fertilizers), or poor drainage.

To maintain continuous flowering, deadhead spent blooms regularly, though allowing some seed heads to remain will encourage beneficial self-seeding. If plants become leggy or sparse in flowering by mid-summer, a light trim of about one-third of the height can rejuvenate growth and flowering, especially in warmer climates with long growing seasons.

Why does Verbena Bonariensis turn bitter?

Verbena bonariensis is not grown for consumption, so bitterness is not a concern as it would be with edible plants. However, the plant may develop other issues that affect its appearance or performance:

• Yellowing leaves – Usually indicates overwatering or poor drainage; ensure soil drains well and reduce watering frequency.
• Reduced flowering – Often caused by insufficient sunlight; move to a sunnier location if possible.
• Stunted growth – May result from nutrient-poor soil; apply a light balanced fertilizer in spring.
• Brown leaf edges – Typically drought stress; increase watering during dry periods until established.
• Leggy growth – Can occur in too much shade or overly rich soil; provide more sun and avoid over-fertilizing.

Companion planting for Verbena Bonariensis

Verbena bonariensis makes an excellent companion for many garden plants due to its airy growth habit that doesn’t compete heavily for space or resources. Good companions include:

• Ornamental grasses – The contrasting textures create beautiful visual interest, and both tend to prefer similar growing conditions.
• Echinacea (Coneflowers) – These native wildflowers attract similar pollinators and create a meadow-like effect when planted together.
• Rudbeckia (Black-eyed Susans) – The yellow flowers complement verbena’s purple, and both are excellent pollinator plants.
• Achillea (Yarrow) – Another drought-tolerant perennial that shares similar growing requirements and pollinator benefits.
• Salvia – Creates a tiered effect with verbena’s taller stems rising above salvia’s bushier habit.
• Lavender – Both plants prefer similar well-draining soil conditions and minimal watering once established.

Avoid planting near:

• Moisture-loving plants – Verbena’s drought tolerance means it doesn’t thrive in the consistently moist soil that hydrangeas or astilbes prefer.
• Aggressive spreaders – Plants like mint or certain groundcovers may overwhelm verbena seedlings.

Seasonal calendar

Spring (March-May):

• Cut back previous year’s growth to 15-20 cm (6-8 inches) in early spring
• Start seeds indoors 8-10 weeks before last frost (cool regions)
• Apply light balanced fertilizer to established plants
• Plant out seedlings or nursery plants after last frost
• Thin self-sown seedlings if desired

Summer (June-August):

• Water during extended dry periods
• Deadhead spent flowers to encourage continued blooming
• Monitor for pests and diseases
• Cut flowers for arrangements as desired
• Light pruning in mid-summer can rejuvenate plants in warm climates

Autumn (September-November):

• Reduce watering as temperatures cool
• Allow some seedheads to remain for winter interest and self-seeding
• Plant in warm regions for establishment before next summer
• Apply mulch around crowns in colder regions (zones 5-6)

Winter (December-February):

• Leave dried stems for winter interest and wildlife habitat
• Order seeds for next season
• Plan garden layout incorporating verbena
• In mild winter areas, plants may remain semi-evergreen

Problems & solutions

Common questions about growing Verbena Bonariensis

How often should I water Verbena bonariensis?

Water newly planted verbena regularly until established, then reduce to weekly deep watering during dry periods. Once established (usually after the first growing season), these plants are quite drought-tolerant and typically only need supplemental watering during extended dry spells.

Can Verbena bonariensis grow in partial shade?

While verbena bonariensis prefers full sun (6+ hours daily), it can tolerate partial shade, especially in hotter climates. However, plants grown in too much shade will become leggy and produce fewer flowers, reducing their value to pollinators.

What size container is suitable for growing Verbena bonariensis?

Choose a container at least 30 cm (12 inches) deep and wide with excellent drainage. Compact varieties like ‘Lollipop’ or ‘Meteor Shower’ are better suited to container growing than the taller species type.

How far apart should I space Verbena bonariensis plants?

Space plants 30-45 cm (12-18 inches) apart. Despite their tall height, they have a relatively small footprint at ground level, allowing them to weave between other plants without overwhelming them.

Is Verbena bonariensis frost hardy?

Established plants are hardy to approximately -10°C (14°F) or USDA zones 7-11, though the crown may survive colder temperatures with protection. In zones 5-6, apply thick mulch around the crown in autumn to improve winter survival. In very cold regions, grow as an annual or in containers that can be protected.

Will Verbena bonariensis come back every year?

In suitable climates (USDA zones 7-11), verbena bonariensis is a short-lived perennial that returns for several years. In colder regions, it may not survive winter but often self-seeds readily, with new plants appearing in spring. Some gardeners in colder areas treat it as an annual.

How can I prevent Verbena bonariensis from spreading too much?

To control spreading, deadhead flowers before they set seed. Remove unwanted seedlings in spring when they’re small and easy to identify. In some gardens, this self-seeding habit is considered beneficial, creating a naturalistic look with plants appearing in unexpected but often aesthetically pleasing locations.