Does it need staking?

No, the stems are quite wiry and strong enough to support the flower heads.

It is a short lived perennial that is often grown as an annual in colder climates.

Plant guide

Purpletop vervain.

Verbena bonariensis

Pronounced ver-BEE-nah bon-ar-ee-EN-sis

Also known as Argentina vervain, Argentine Vervain, Argentinian Vervain, Cluster-flower Verbena, Cluster-flower Vervain, Purpletop, Purpletop Verbena, Purpletop Vervain

This tall, airy perennial adds a lovely vertical element to garden beds with its clusters of tiny purple flowers. It is a favorite among pollinators like butterflies and bees. The plant is known for its self seeding habit, which helps it persist in the garden.

At a glance

Care level: Easy
Plant type: Herbaceous perennial
Light: Full sun
Indoor light: Direct sun
Water: Every 7 to 14 days
Mature size: 150cm tall by 60cm wide
Growth rate: Fast
Hardiness: USDA 7 to 11
Bloom time: Mid summer to late autumn

Care

Plant in a sunny spot with well draining soil to keep it happy. Watch for powdery mildew if the air circulation is poor, and deadhead spent blooms if you want to prevent excessive self seeding. It is quite drought tolerant once it is established in your garden.

Watering: Water deeply during dry spells, but allow the soil to dry out between waterings.
Feeding: Apply a balanced fertilizer once or twice during the growing season if growth seems sluggish.
Pruning: Cut back the dead stems to the ground in late winter or early spring.
Repotting: If growing in a container, refresh the soil every couple of years to keep it vigorous.
Soil: Well draining, fertile soil
Soil pH: Neutral to slightly acidic
Temperature: -10 to 35°C
Humidity: 40 to 70%
Drought tolerance: Moderate
Lifespan: Short lived perennial, typically 3 to 5 years.
Fragrance: Light
Deer and rabbits: High

Signs it needs repotting

Roots growing out of the drainage holes.
Water draining through the pot very quickly.
The plant becoming top heavy and unstable.

Safety

People: The plant is generally considered non toxic but may cause mild stomach upset if ingested.
Pets: This plant is generally considered non toxic to cats and dogs.
Children: The plant is not dangerous, but the stems are slightly prickly and should be handled with care.
Contact allergens: The rough, hairy stems can cause minor skin irritation in sensitive individuals.
Airborne allergens: The pollen is not typically considered a major allergen.
Edibility: This plant is not considered edible and should not be consumed.

How to identify it

Tall, slender, square stems
Clusters of tiny purple flowers
Rough, lance shaped leaves
Open, branching habit

Height: 0.9 to 1.5m
Spread: 0.3 to 0.6m
Leaves: dark green, deciduous
Flowers: lavender, purple, 0.5 to 1cm

Problems to watch for

Powdery MildewCommon
AphidsUncommon
Leaf SpotUncommon
Root RotUncommon

By symptom

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Growing it

Propagation: seed, cuttings
When to plant: spring
Overwintering: Cut back the dead stems in late winter or early spring to make room for new growth. In colder areas, apply a light mulch to protect the crown from freezing temperatures.
In containers: It grows well in large containers, provided they have excellent drainage and at least 30 centimeters of depth.

Seed

Sow seeds indoors in late winter.
Keep the soil moist and warm until germination.
Transplant outdoors once the danger of frost has passed.

Cuttings

Take softwood cuttings in late spring.
Place them in a moist, well draining potting mix.
Keep in a bright spot until roots develop.

Plant in groups of three or five to create a natural, drifting effect in the garden.

Grows well with

Purple Coneflower — They share similar sun and water needs while providing a lovely color contrast.
Ornamental Grasses — The airy flowers of the verbena look beautiful swaying against the texture of ornamental grasses.

Similar species

Brazilian Verbena — It is a lower growing relative with a similar flower color and habit.

Science

Family: Verbenaceae
Genus: Verbena
Order: Lamiales
Class: Magnoliopsida
Native range: South America, including Argentina and Brazil.
Conservation: It is not of conservation concern and is widely naturalized in many regions.

It thrives in open, sunny areas and disturbed soils where it can easily disperse its seeds.

Value to wildlife: nectar source, attracts beneficial insects
Pollinators: bees, butterflies, moths
Uses: pollinator gardens, cottage gardens, meadow plantings, cut flowers

Through the year

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Flowering

Fruiting

Foliage

Ecological indicators

Soil reaction: 6/9
Light: 8/9
Temperature: 6/9
Moisture: 4/9
Salinity: 2/9
Nutrients: 4/9

Taxonomy resolved against GBIF.

Questions people ask

Does it need staking?: No, the stems are quite wiry and strong enough to support the flower heads.
Is it a perennial?: It is a short lived perennial that is often grown as an annual in colder climates.

Where the name comes from

The species name bonariensis refers to Buenos Aires, where the plant was first described.

Good to know

It is often called tall verbena because of its slender, upright stems.
The flowers are highly attractive to swallowtail butterflies.
It self seeds readily in the garden, often appearing in unexpected places.
Despite its height, it rarely needs staking due to its wiry, strong stems.

Also in

Deer-resistant plants

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This guide was generated with AI and checked against GBIF taxonomy. It is general information, not horticultural or veterinary advice. Read about how we build these guides.