Supporting Tall Perennials: Subtle Structures for Elegant Borders

Few things are more glorious than a border that stands confidently tall through the summer - soaring delphiniums, airy verbena, stately echinops and swaying grasses give the garden scale and generosity. They create depth, rhythm and that unmistakable English border abundance seen at RHS Wisley or in the long borders at Hidcote.

Yet by July, many tall perennials begin to lean. After heavy rain or wind stems splay outward and carefully tended planting can quickly look exhausted rather than exuberant

The solution isn’t to avoid tall plants, it’s to support them properly and - most importantly - subtly.

Here’s our tips on how to maintain height and elegance in your UK garden without visible stakes or unsightly string.

Why Tall Perennials Flop

Tall perennials collapse for several reasons:

• Soft, rain-heavy growth in fertile soil
• Wind exposure in open gardens
• Crowded borders competing for light
• Shallow root systems
• Insufficient early support

In the UK climate - with our combination of mild winters (when it feels like the rain will never stop!), rapid spring growth and unpredictable summer storms - staking too late is a common mistake.

Take a leaf out of the designers playbook - professional gardeners rarely wait until plants have fallen - structure is introduced early and allowed to magically disappear as growth fills in.

The Best Tall Perennials for Height in UK Gardens

Height gives a garden presence and some of our favourite tall performers regularly used on Agriframes award-winning stand at RHS Chelsea Flower Show are include:

Sun-Loving Tall Perennials

• Delphinium
• Echinops (globe thistle)
• Verbena bonariensis
• Phlox paniculata
• Rudbeckia
• Aster
• Perovskia (Russian sage)

Partial Shade

• Astrantia
• Digitalis (foxglove)
• Campanula lactiflora
• Thalictrum

Moist or Dappled Shade

• Rodgersia
• Persicaria
• Ligularia

These plants provide architectural lift  but most benefit from discreet support, particularly in exposed gardens or larger planting schemes.

Subtle Structure Is the Key

The most elegant borders don’t look staked - but you’d be amazed at what is going on behind the scenes!

At RHS Harlow Carr, supports are installed early in the season so that stems grow through them - by flowering time, the structure is virtually invisible.

This is where purpose-built supports outperform improvised canes or netting - thoughtfully chosen supports can remain in place throughout the season and will still look attractive and purposeful - with or without growth around them.

Why Metal Supports Work Best

Lightweight bamboo often shifts, splits or draws unwanted attention to itself, while Agriframes metal plant supports offer:

• Strength without bulk
• Long lasting durability
• Consistent height and proportion

Early Placement Makes All the Difference

One of the simplest professional tricks is early positioning- place supports in March or April when growth is just emerging. As stems lengthen, they grow naturally through the framework, creating:

• Upright posture
• Even distribution
• Wind resistance
• Natural-looking containment

By the time flowers appear, the structure is hidden.

This approach mirrors techniques used in historic English herbaceous borders, where supports are considered part of the garden’s invisible framework.

Agriframes Guide to Matching Support to Plant Type

Not all tall perennials require the same approach.

Columnar Plants such as Delphinium and Foxglove)

Use tall ring supports positioned centrally to prevent leaning.

Airy, Branching Plants like Verbena and Aster

Low, wider supports prevent outward splaying while maintaining movement.

Dense Clumps including Phlox and Rudbeckia

Circular or half-ring supports hold the entire clump in place.

Tall Ornamental Grasses

Often self-supporting, but in exposed gardens may benefit from subtle containment rings to prevent wind damage.

Shade vs Sun – Why It Matters

Shade-grown perennials often stretch toward light, producing softer stems. In partially shaded UK gardens, foxgloves and campanula can lean if unsupported.

In full sun, growth may be denser but equally vulnerable to heavy rain.

In both situations, early support is your friend.

Creating Movement Without Chaos

Tall perennials should move and the goal is to avoid rigidity. This balance between structure and softness is at the heart of classic English planting design - abundant yet controlled.

Well-designed supports allow:

• Gentle sway
• Light penetration
• Natural growth habit

They prevent collapse without creating stiffness.

Winter Upkeep

When borders are cut back, metal supports can be removed or left in place depending on design preference.

Many gardeners remove them in late autumn, but in larger borders they can remain discreetly positioned ready for spring growth.

Either way, durable metal supports outlast temporary staking year after year.

Height with Confidence

Tall perennials are essential for depth and drama - without them borders can feel static and misproportioned.

The answer is not to reduce height but to support it intentionally and with anticipation.

By introducing subtle, well-proportioned metal frameworks early in the season you preserve the natural elegance of the planting while protecting it from the challenges of the British weather.

Strong structure allows tall planting to perform at its best - season after season.