10 architectural plants

• By
• Christian Barnard

Image by Christian Barnard

An architectural plant makes a statement and provides its audience with a sense of awe. Its flower colour is insignificant, as these plants are chosen for their unique growing habits, branching structure and foliage.

I have chosen grasses, biannuals and perennials for this list because I enjoy the suspense as the previous years’ framework is removed to make way for the development of the coming growing season’s burst of vegetation.

I admire these plants—they are musical in composition with their vegetation rising from its base into a crescendo of summer song.

1. Vernonia crinita 'Mammuth'

Common name: Ironweed
Family: Asteraceae
Typical height and width: 240cm x 100cm

I have heard this plant referred to as an “Aster on steroids.” Its stately structure provides vertical interest in the garden while attracting an abundance of bees and butterflies with its sky-high purple flowers.

2. Salivia Uglinosa

Common name: Bog salvia
Family: Lamiaceae
Typical height and width: 180cm x 50cm

Stunning clear blue flowers appear in spikes on top of tall stems from summer to autumn. In my garden, it dots itself amongst grasses and perennials, taking up very little space at its base. A brilliant yet underused architectural plant.

3. Calamagrostis brachytricha

Common name: Korean feather reed grass
Family: Poaceae
Typical height and width: 120cm x 50cm

Strong and upright in full sun, this grass provides a fine and delicate texture to the garden’s composition. Dense silver inflorescences leap out of finely textured mounds of grey-green foliage, bringing a sense of magic to the garden—particularly when the wind blows.

4. Sedum 'Matrona'

Common name: Stone crop
Family: Crassulaceae
Typical height and width: 80cm x 80cm

This perennial has a short and stout structure, bringing a strong horizontal plane to any planting scheme. Best planted in generous drifts, the flowers are a valuable nectar source for butterflies and bees.

5. Digitalis ferruginea ‘Gigantea’

Common name: Rusty Foxglove
Family: Scrohulariaceae
Typical height and width: 150cm x 30cm

A classic architectural plant with its distinctive copper-hued spires of golden-brown tubular flowers that appear during mid-summer. Do not cut it back after flowering, as it will hold its stately stance through winter. Although short-lived, given the right conditions, it will perpetuate by self-seeding.

6. Inula helenium 'Goliath'

Common name: Elecampane
Family: Compositae
Typical height and width: 200cm x 120cm

A tall, perfectly proportioned perennial that commands attention wherever it grows. The flower spike emerges from its textured base in early summer and skyrockets up to 200 centimetres tall, carrying medium-sized yellow flowers that continue their display up until first frost.

7. Cynara cardunculus

Common name: Cardoon
Family: Asteraceae
Typical height and width: 250cm x 150cm

The magnificent purple, thistle-like flowers of this stately cardoon are held above clumps of confident deeply cut, silvery-green leaves. A highly architectural plant with robust serrated foliage and a strong branching structure.

8. Miscanthus sinensis 'Kleine Silberspinne'

Common name: Little silver spider
Family: Poeceae
Typical height and width: 160cm x 120cm

Slender green leaves have a white stripe down the centre and masses of vertical, feathery russet-coloured plumes that fade to silver in the autumn. My favourite Miscanthus, the little silver spider, provides a splash of fine foliage that would satisfy even without the feathery panicles that appear just above.

9. Epilobium angustifolium

Common name: Fireweed
Family: Onagraceae
Typical height and width: 200cm x 100cm

Towers of purple flowers appear on arching stalks from mid-summer. Fireweed is generally under appreciated and often considered to be a weed. However, I cultivate this plant in my own garden and admire it for its naturalistic character, easy care and ability to support wildlife.

10. Peucedanum verticillare

Common name: hog fennell (not hog weed!)
Family: Apiaceae
Typical height and width: 220cm x 80cm

Not for the timid, this plant will need space to thrive; however, it will act as a continual conversation piece and certainly won’t fail to impress. This makes an architectural feature that lasts well into winter, with its ghostly framework standing proud of its neighbours.