How to Grow Verbena bonariensis in the UK: Complete Growing Guide

Growing Verbena bonariensis in the UK is a fantastic way to add height, colour and wildlife interest to your garden or allotment.

This beautiful perennial plant produces tall, slender stems topped with clusters of tiny purple flowers. Unlike many tall border plants, Verbena bonariensis has an airy appearance, allowing you to see other flowers growing behind it.

It’s particularly popular in cottage gardens, prairie-style planting schemes, wildlife gardens and mixed perennial borders.

One of the biggest advantages of Verbena bonariensis is its exceptionally long flowering season.

In suitable conditions, it can produce flowers from June or July right through to October, sometimes continuing until the first significant frosts.

The flowers are particularly attractive to butterflies, bees and other pollinating insects, making this an excellent plant for anyone wanting to encourage wildlife into their garden.

Here at Gardening with Ben, I enjoy growing flowers alongside vegetables because they help create a colourful, wildlife-friendly allotment.

Verbena bonariensis is a brilliant choice because its tall stems take up relatively little space near ground level, while its flowers provide plenty of colour above surrounding plants.

Although Verbena bonariensis is a perennial, it can be short-lived in colder or wetter UK gardens.

Fortunately, it often self-seeds, meaning new plants may appear naturally each year.

In this complete growing guide, we’ll explore everything you need to know about growing Verbena bonariensis successfully.

We’ll cover sowing seeds, planting, soil requirements, watering, feeding, pruning, winter care, growing in pots, collecting seeds and dealing with common problems.

We’ll also explain how to encourage more flowers and why this plant is so valuable for butterflies and bees.

What Is Verbena bonariensis?

Verbena bonariensis is a flowering perennial belonging to the Verbenaceae family.

It originates from South America, including Argentina and neighbouring regions.

It’s sometimes known as purpletop vervain or tall verbena.

The plant produces upright, branching stems with clusters of small purple flowers.

Its narrow growth habit makes it particularly useful for planting among other perennials.

How Tall Does Verbena bonariensis Grow?

Established plants commonly reach approximately 1.2–2 metres tall.

Some compact varieties remain much shorter.

How Wide Does It Grow?

Plants may spread approximately 30–60cm or more, depending on variety and growing conditions.

Is Verbena bonariensis Evergreen?

No.

In many UK gardens, the upper growth dies back during winter.

New shoots may emerge from the base during spring if the plant survives.

Verbena bonariensis Growing Facts

Feature	Details
Botanical name	Verbena bonariensis
Common names	Tall verbena, purpletop vervain
Plant family	Verbenaceae
Plant type	Short-lived perennial
Typical height	1.2–2m
Typical spread	30–60cm
Flower colour	Purple-violet
Flowering season	June/July–October
Preferred position	Full sun
Soil	Well-drained
Indoor sowing	February–April
Planting outside	May–June, after frost risk
Winter hardiness	Variable; vulnerable to cold, wet conditions
Pollinator friendly	Yes
Self-seeding	Common in suitable conditions

Why Grow Verbena bonariensis?

There are many reasons to include this plant in your garden.

Excellent for Butterflies

The nectar-rich flowers are attractive to visiting butterflies.

Popular with Bees

Bees and other pollinating insects frequently visit the flower clusters.

Long Flowering Season

Plants can flower for several months.

Adds Height Without Blocking Views

The slender stems create height while allowing other plants to remain visible.

Ideal for Cottage Gardens

Verbena combines beautifully with traditional flowering perennials.

Useful for Allotments

It can be grown in permanent flower borders and wildlife areas.

Often Self-Seeds

New seedlings may appear naturally in suitable conditions.

Low Maintenance

Established plants generally require relatively little attention.

Best Verbena bonariensis Varieties to Grow

Several varieties and related selections are available.

Verbena bonariensis

The traditional tall form.

Produces slender stems and clusters of purple flowers.

Best for: Cottage gardens, wildlife borders and prairie-style planting.

Verbena bonariensis ‘Lollipop’

A compact variety producing similar purple flowers on much shorter stems.

Plants commonly reach approximately 60cm tall.

Best for: Smaller gardens, containers and front-to-middle borders.

Verbena bonariensis ‘Meteor Shower’

A relatively compact, branching selection that produces numerous purple flower clusters.

Best for: Containers and smaller planting spaces.

Which Variety Should You Choose?

For tall, airy borders, choose traditional Verbena bonariensis.

For smaller gardens or containers, compact selections such as ‘Lollipop’ may be more suitable.

When to Sow Verbena bonariensis Seeds in the UK

Verbena bonariensis can be grown from seed.

However, germination can sometimes be irregular.

Best Time to Sow Indoors

February through April is generally suitable.

Can You Sow Verbena in January?

Yes, with suitable growing equipment and lighting.

However, early sowing isn’t essential.

Can You Sow Verbena in March?

Yes.

March is a good time to begin indoor sowing.

Can You Sow Verbena in April?

Yes.

April sowings can produce healthy plants for summer planting.

Can You Sow Verbena in Autumn?

Yes.

Seeds can be sown during autumn and kept under suitable protected conditions.

Some seeds benefit from exposure to cooler temperatures.

UK Verbena bonariensis Growing Calendar

Month	Gardening activity
January	Plan varieties and check overwintering plants
February	Begin indoor sowing
March	Sow seeds and check emerging perennial growth
April	Pot on seedlings
May	Harden off and begin outdoor planting
June	Main planting and early flowering
July	Enjoy flowers and pollinator activity
August	Continue flowering and check moisture
September	Enjoy late flowers and collect seeds
October	Leave selected seed heads and prepare for winter
November	Leave stems standing for winter protection
December	Check drainage and protect vulnerable plants

How to Grow Verbena bonariensis from Seed

Growing Verbena bonariensis from seed is rewarding, although patience may be necessary.

Step 1: Prepare Seed Trays

Use clean seed trays or small pots.

Step 2: Fill with Compost

Choose suitable peat-free seed compost.

Step 3: Sow Seeds Thinly

Scatter seeds across the compost surface.

Step 4: Cover Lightly

Follow the seed packet instructions.

A very light covering of compost or vermiculite is commonly recommended.

Step 5: Water Carefully

Use a fine mist or water from below.

Step 6: Provide Suitable Conditions

A temperature around 18–21°C may encourage germination.

Step 7: Be Patient

Germination can be irregular.

Some seeds emerge within a few weeks, while others take considerably longer.

Step 8: Consider Cold Treatment

If the seed supplier recommends cold stratification, follow those instructions.

Some seed batches germinate more successfully after a period of cool conditions.

Step 9: Provide Good Light

Once seedlings emerge, move them into a bright position.

Step 10: Pot On

Transfer seedlings into individual pots when they’re large enough to handle.

Step 11: Grow Plants On

Keep seedlings in bright, frost-free conditions.

Step 12: Harden Off

Gradually introduce plants to outdoor conditions before planting.

Why Are My Verbena Seeds Not Germinating?

Verbena bonariensis can have unpredictable germination.

Possible causes include:

• Dormant seeds
• Unsuitable temperature
• Compost drying out
• Excessive moisture
• Old seed
• Seeds requiring different temperature conditions

What Should You Do?

Check the seed packet instructions.

Maintain suitable moisture without waterlogging.

Allow additional time.

Where appropriate, follow the supplier’s advice on cold stratification.

Avoid discarding trays too quickly because germination may be delayed.

When to Plant Verbena bonariensis Outside in the UK

Young Verbena bonariensis plants should generally be planted outdoors after the risk of damaging frost has passed.

Southern England

May is often suitable.

Northern England

Late May or early June may be safer.

Scotland and Exposed Gardens

June may be preferable.

Should You Harden Off Plants?

Yes.

Gradually acclimatise indoor-grown plants to outdoor conditions over approximately one to two weeks.

Where Is the Best Place to Grow Verbena bonariensis?

Verbena bonariensis performs best in sunny, well-drained positions.

Full Sun

Choose somewhere receiving plenty of direct sunlight.

Light Shade

Plants may tolerate light shade, but flowering can be reduced.

Well-Drained Soil

Good drainage is particularly important during winter.

Sheltered Positions

Shelter can reduce wind damage, although established plants are often surprisingly resilient.

Cottage Garden Borders

The airy stems combine beautifully with other flowers.

Wildlife Gardens

The nectar-rich flowers provide resources for pollinating insects.

Best Soil for Growing Verbena bonariensis

Verbena bonariensis prefers well-drained soil.

Sandy Soil

Often suitable, provided plants receive enough moisture while establishing.

Loamy Soil

Usually excellent.

Clay Soil

Can be suitable if drainage is improved.

Poor Soil

Established plants can tolerate relatively lean soil.

Rich Soil

Excessively fertile conditions may encourage lush growth rather than strong, balanced plants.

Avoid Waterlogging

Wet winter soil is a major cause of plant losses.

How to Plant Verbena bonariensis Step by Step

Step 1: Choose a Sunny Position

Select somewhere with good drainage.

Step 2: Prepare the Soil

Remove weeds and loosen compacted ground.

Step 3: Improve Drainage if Necessary

Address poorly drained soil before planting.

Step 4: Water the Plant

Water the pot before planting.

Step 5: Dig a Planting Hole

Make the hole large enough for the root ball.

Step 6: Position the Plant

Plant at approximately the same depth as it was growing in its pot.

Step 7: Backfill

Replace soil around the roots.

Step 8: Firm Gently

Remove large air pockets.

Step 9: Water Thoroughly

Water immediately after planting.

Step 10: Allow Room to Grow

Remember that traditional Verbena bonariensis can become tall.

How Far Apart Should You Plant Verbena bonariensis?

Spacing depends on the variety.

Traditional Tall Verbena

Approximately 30–45cm apart is suitable for many planting schemes.

Compact Varieties

Follow the supplier’s recommended spacing.

Why Does Spacing Matter?

Adequate spacing allows healthy growth and improves airflow.

Can You Plant Verbena Close Together?

Yes, plants can be grouped for a fuller display, but avoid excessive overcrowding.

How to Grow Verbena bonariensis in Pots

Verbena bonariensis can be grown in containers.

Compact varieties are particularly suitable.

Choosing a Pot

Select a stable container with drainage holes.

Best Compost

Use suitable peat-free multipurpose compost with good drainage.

Position

Place containers somewhere sunny.

Watering

Check compost regularly during warm weather.

Feeding

Use modest feeding if necessary.

Support

Tall varieties may need support in exposed positions.

Winter Protection

Container-grown plants are more vulnerable to cold because their roots are exposed.

Move pots into a sheltered position during severe winter weather.

How Often Should You Water Verbena bonariensis?

Verbena bonariensis is relatively drought tolerant once established.

Newly Planted Verbena

Water regularly while roots establish.

Established Border Plants

Water during prolonged dry spells.

Container-Grown Verbena

Pots require more frequent watering.

Avoid Overwatering

Persistently saturated soil can damage roots.

Best Watering Method

Water deeply around the base when necessary.

Does Verbena bonariensis Need Feeding?

Verbena bonariensis generally doesn’t require heavy feeding.

Garden-Grown Plants

Plants growing in reasonably fertile soil often need little additional fertiliser.

Poor Soil

A modest application of suitable balanced fertiliser may help.

Container Plants

Potted plants may benefit from occasional feeding.

Avoid Excess Nitrogen

Too much nitrogen can encourage soft, leafy growth.

When Does Verbena bonariensis Flower in the UK?

Verbena bonariensis generally flowers from summer into autumn.

Early Flowering

Some established plants may begin flowering during June.

Main Flowering Season

July through September is often the main period.

Autumn Flowering

Flowers may continue into October.

When Does Flowering Stop?

Significant frost usually ends the flowering season.

How to Keep Verbena bonariensis Flowering

Verbena bonariensis naturally produces flowers over a long period.

However, suitable care can help maintain healthy plants.

Provide Full Sun

Sunshine encourages strong flowering.

Avoid Waterlogging

Healthy roots support flowering.

Water During Severe Drought

New plants particularly benefit from moisture.

Avoid Excessive Feeding

Overfeeding can encourage excessive foliage.

Remove Damaged Growth

Keep plants healthy.

Allow Natural Branching

Established plants often produce multiple flowering stems.

Should You Deadhead Verbena bonariensis?

Deadheading isn’t always necessary.

Verbena bonariensis naturally produces flowers over an extended period.

Benefits of Deadheading

Removing faded flower clusters can keep plants tidy.

It may encourage further flowering.

Why Leave Some Flowers?

Allowing selected flower heads to mature encourages seed production.

Best Approach

Deadhead some stems if desired, but leave others to develop seeds.

This can help encourage self-seeding.

When to Cut Back Verbena bonariensis in the UK

Pruning is an important part of winter care.

Should You Cut Verbena Back in Autumn?

Generally, it’s better to leave the stems standing through winter.

Why Leave the Stems?

Old stems can provide some protection to the plant’s crown.

They also offer winter structure.

Best Time to Cut Back

Spring, usually March or April, is generally suitable.

What Should You Do in Spring?

Remove dead stems once new growth begins appearing.

How Far Should You Cut Back?

Cut dead stems close to the base, taking care not to damage emerging shoots.

How to Prune Verbena bonariensis Step by Step

Step 1: Wait Until Spring

Avoid cutting everything back during autumn.

Step 2: Check for New Growth

Look for fresh shoots near the base.

Step 3: Identify Dead Stems

Old stems may be dry and brittle.

Step 4: Use Clean Secateurs

Use sharp cutting tools.

Step 5: Remove Dead Growth

Cut old stems close to the base.

Step 6: Avoid Damaging New Shoots

Work carefully around emerging growth.

Step 7: Remove Debris

Clear away unwanted dead material.

Step 8: Check Plant Health

Look for signs of healthy regrowth.

Is Verbena bonariensis Perennial in the UK?

Yes.

Verbena bonariensis is a perennial plant.

However, it’s often short-lived in UK conditions.

Why Do Some Plants Die in Winter?

Cold weather and persistently wet soil can damage the crown and roots.

Can Verbena Survive Frost?

Established plants may tolerate some frost, particularly in sheltered, well-drained locations.

Is It Fully Reliable Every Year?

No.

Winter survival varies depending on location and conditions.

Why Does It Often Return?

Some plants survive and regrow from the crown.

Others return through self-seeding.

How to Overwinter Verbena bonariensis

Verbena bonariensis can survive winter in suitable conditions.

Leave Stems Standing

Avoid cutting plants back hard during autumn.

Improve Drainage

Good drainage is particularly important.

Choose a Sheltered Position

Shelter may help reduce exposure.

Apply Mulch Carefully

A modest layer of suitable mulch can help protect the root zone.

Avoid piling wet material directly over the crown.

Protect Containers

Move pots into a sheltered position during severe weather.

Avoid Excessive Winter Watering

Keep container compost from remaining constantly saturated.

Does Verbena bonariensis Self-Seed?

Yes.

Verbena bonariensis commonly self-seeds in suitable gardens.

How Does Self-Seeding Work?

Flowers develop seeds.

Mature seeds fall onto surrounding soil.

Some seeds germinate when conditions become suitable.

When Do Seedlings Appear?

Seedlings often appear during spring or early summer.

How to Encourage Self-Seeding

Leave selected flower heads to mature.

Avoid disturbing all surrounding soil.

Allow some bare or lightly covered ground where seeds can germinate.

Can Self-Seeding Become a Problem?

Yes.

In suitable conditions, Verbena bonariensis can spread beyond its original planting position.

Remove unwanted seedlings before they establish.

How to Collect Verbena bonariensis Seeds

Collecting seeds is a useful way to grow more plants.

Step 1: Leave Flower Heads

Allow selected flowers to mature.

Step 2: Wait for Seed Development

Seed heads gradually dry.

Step 3: Collect During Dry Weather

Cut mature seed heads carefully.

Step 4: Dry Thoroughly

Allow seed heads to dry in a ventilated location.

Step 5: Separate Seeds

Gently remove seeds.

Step 6: Store Correctly

Use labelled paper packets.

Step 7: Keep Cool and Dry

Store until the next sowing season.

Can You Take Cuttings from Verbena bonariensis?

Yes.

Verbena bonariensis can be propagated from cuttings.

Best Time

Late spring or early summer is generally suitable.

How to Take Cuttings

1. Choose healthy, non-flowering growth.
2. Cut a suitable section below a leaf joint.
3. Remove lower leaves.
4. Insert into suitable propagation compost.
5. Keep in bright, indirect light.
6. Maintain moisture without waterlogging.
7. Allow roots to develop.
8. Pot on when established.

Why Take Cuttings?

Cuttings can provide replacement plants if the original plant doesn’t survive winter.

Is Verbena bonariensis Good for Butterflies?

Yes.

Verbena bonariensis is widely valued as a butterfly-friendly flowering plant.

Why Do Butterflies Like It?

The small flowers provide accessible nectar.

Which Butterflies May Visit?

Depending on location and season, visitors may include:

• Red admirals
• Peacocks
• Small tortoiseshells
• Painted ladies
• Commas

Best Planting Approach

Grow several plants together to create a noticeable display.

Combine verbena with other nectar-rich flowers.

Is Verbena bonariensis Good for Bees?

Yes.

The flowers can attract honeybees, bumblebees and other pollinating insects.

Why Is It Useful?

Verbena flowers during summer and autumn.

This provides nectar during an important period for many pollinators.

Best Advice

Combine Verbena bonariensis with flowers that bloom during spring and early summer.

This helps provide a longer season of floral resources.

Common Problems When Growing Verbena bonariensis

Verbena bonariensis is generally easy to grow once established, but several problems can occur.

Seeds Not Germinating

Germination can be irregular.

Yellowing Leaves

Possible causes include waterlogging, drought or nutrient problems.

Plants Not Flowering

Insufficient sunlight or immature growth may be responsible.

Tall Stems Falling Over

Strong winds or overly lush growth may cause leaning.

Powdery Mildew

White powdery growth can appear on foliage.

Aphids

Aphids may gather on tender shoots.

Root Rot

Poor drainage can damage roots.

Winter Losses

Cold, wet conditions can kill established plants.

Why Is My Verbena bonariensis Not Flowering?

Several factors may be responsible.

Insufficient Sunlight

Plants generally flower best in full sun.

Young Plants

Seed-grown plants may need time to mature.

Excessive Nitrogen

Heavy feeding can encourage leafy growth.

Poor Growing Conditions

Waterlogging or severe drought can affect plant health.

Late Planting

Plants established late in the season may flower later.

Why Is My Verbena bonariensis Falling Over?

Traditional Verbena bonariensis produces tall stems.

Although these are often surprisingly strong, some plants may lean.

Common Causes

• Strong winds
• Excessive feeding
• Crowded growing conditions
• Weak stems
• Heavy rain

How to Support Plants

Use discreet supports where necessary.

Best Supports

• Bamboo canes
• Twiggy branches
• Plant rings
• Suitable garden supports

Best Companion Plants for Verbena bonariensis

Verbena combines beautifully with many garden flowers.

Cosmos

Cosmos produces airy flowers that complement verbena’s slender stems.

Rudbeckia

Rudbeckia provides strong yellow colour.

Echinacea

Echinacea creates attractive purple and pink combinations.

Salvias

Salvias offer contrasting flower shapes.

Dahlias

Dahlias provide larger flowers beneath verbena’s tall stems.

Ornamental Grasses

Grasses create attractive movement and structure.

Asters

Asters extend colour into autumn.

Gaura

Gaura produces delicate flowers that complement verbena’s airy appearance.

Can You Grow Verbena bonariensis on an Allotment?

Yes.

Verbena bonariensis is excellent for permanent allotment flower borders and wildlife areas.

Suitable Locations

• Flower borders
• Around sheds
• Wildlife gardens
• Permanent raised beds
• Pathway edges
• Cutting gardens

Benefits

It provides colourful flowers and attracts pollinating insects.

Important Consideration

Traditional Verbena bonariensis can grow tall.

Avoid planting it where it may shade smaller crops.

Self-Seeding

Remove unwanted seedlings from vegetable-growing areas.

Frequently Asked Questions About Growing Verbena bonariensis

Is Verbena bonariensis Easy to Grow in the UK?

Yes. Once established, it’s relatively easy to maintain in suitable conditions.

When Should You Sow Verbena bonariensis Seeds?

Usually February through April indoors.

Can You Sow Verbena in March?

Yes. March is a suitable sowing month.

How Long Does Verbena bonariensis Take to Germinate?

Germination can take several weeks and may be irregular.

Do Verbena Seeds Need Cold Stratification?

Some seed batches benefit from cold treatment. Follow the supplier’s instructions.

When Can You Plant Verbena Outside?

Usually May or June, after damaging frost risk has passed.

Does Verbena bonariensis Need Full Sun?

Yes. Full sun generally produces the best flowering.

Can Verbena Grow in Shade?

It tolerates light shade, but flowering may be reduced.

What Soil Does Verbena Prefer?

Well-drained soil.

Can Verbena Grow in Clay Soil?

Yes, if drainage is adequate.

Can You Grow Verbena bonariensis in Pots?

Yes. Compact varieties are particularly suitable.

How Tall Does Verbena bonariensis Grow?

Traditional plants commonly reach approximately 1.2–2m.

How Far Apart Should You Plant Verbena?

Approximately 30–45cm is suitable for many traditional plants.

How Often Should You Water Verbena?

Water regularly during establishment and during prolonged dry spells.

Does Verbena Need Feeding?

Usually very little additional fertiliser.

When Does Verbena bonariensis Flower?

Usually June or July through October.

Does Verbena Flower Until October?

Yes, in favourable conditions.

Should You Deadhead Verbena bonariensis?

It’s optional. Deadheading can keep plants tidy, while leaving flowers encourages seed production.

When Should You Cut Back Verbena bonariensis?

Usually during spring.

Should You Cut Verbena Back in Autumn?

Generally, it’s better to leave stems standing through winter.

Is Verbena bonariensis Perennial?

Yes, although it can be short-lived in colder or wetter gardens.

Does Verbena bonariensis Come Back Every Year?

Some established plants regrow, while others return through self-seeding.

Can Verbena bonariensis Survive Frost?

Established plants may tolerate some frost, but severe cold and winter wet can cause losses.

How Do You Overwinter Verbena?

Leave stems standing, provide good drainage and protect vulnerable container plants.

Does Verbena bonariensis Self-Seed?

Yes, often readily.

Can Verbena Become Invasive?

It can self-seed freely in favourable conditions, so remove unwanted seedlings to prevent excessive spreading.

Can You Collect Verbena Seeds?

Yes. Allow seed heads to mature and dry.

Can You Take Verbena Cuttings?

Yes. Cuttings can be taken from suitable healthy growth.

Is Verbena bonariensis Good for Butterflies?

Yes. It’s an excellent nectar plant for butterflies.

Is Verbena bonariensis Good for Bees?

Yes. Its flowers attract a range of pollinating insects.

Why Is My Verbena Not Flowering?

Insufficient sunlight, immaturity or poor growing conditions may be responsible.

Why Is My Verbena Falling Over?

Strong winds, excessive feeding or weak stems may contribute.

Can You Grow Verbena on an Allotment?

Yes. It’s excellent for permanent flower borders and wildlife-friendly areas.

Final Thoughts: Growing Verbena bonariensis Successfully in the UK

Growing Verbena bonariensis is a wonderful way to add height, movement and beautiful purple flowers to your garden or allotment.

It’s particularly valuable because it combines a long flowering season with excellent pollinator appeal.

The tall, slender stems allow other plants to remain visible, making Verbena bonariensis an excellent choice for mixed borders and cottage gardens.

For the best results, choose a sunny position with well-drained soil.

Start seeds indoors during late winter or spring, or plant established young plants once the risk of damaging frost has passed.

Water regularly during establishment, but avoid keeping the soil excessively wet.

Once established, Verbena bonariensis generally requires relatively little feeding or maintenance.

One of the most important things to remember is to leave the old stems standing through winter.

Cut them back during spring when new growth begins appearing.

And if your plants don’t survive a particularly cold or wet winter, don’t be too disappointed.

Verbena bonariensis often self-seeds, meaning you may discover new plants appearing naturally around your garden.

Whether you’re growing it for butterflies, bees or simply its beautiful purple flowers, Verbena bonariensis is a fantastic addition to a wildlife-friendly UK garden.

Keep smiling, keep shining, keep gardening with Ben!