Nigel Colborn - Plant Solutions

Biennials for summer

Campanula medium

Canterbury Bells Hardy biennial

The showiest of all bell flowers, with rough-textured, simple leaves and thick, ribbed stems. The stems develop into generously endowed spikes whose huge, tubular bell flowers may be shades of blue, pink or white. ‘Cup and saucer’ varieties have a bell flower resting on a petal-like, coloured calyx. Double-flowered varieties are available from seed catalogues.

Soil preference:Well-drained

Aspect:Sun

Season of interest:Summer

Height and spread:1m × 50cm (3ft × 1ft 8in)

Companion plants:A perfect cottage plant, showy but in gentle colours and along with sweet Williams, ideal for bridging the gap between spring and midsummer, following on from wallflowers. Beautiful with roses!

Salvia farinacea

Mealy Sage Tender biennial

Technically a perennial, but grown as a tender biennial or annual, the leaves are glossy but the flower stems are coated with a white mealy substance. The lipped flowers, produced throughout summer, are purple, blue or white. Salvia farinacea ‘Victoria’ is a popular bedding plant.

Soil preference:Any, fertile but free-draining

Aspect:Sun

Season of interest:Summer

Height and spread:1m × 60cm (3ft × 3 ft)

Companion plants:Attractive when included in a tropical mix, perhaps with cannas, bold grasses such as Chasmanthium or ornamental sorghums.

Ratibida columnifera

Mexican Hat Biennial or shortlived perennial

A member of the daisy family from Mexico, with divided leaves and erect stems bearing flowers whose broad, yellow, or red and yellow sterile ray florets surround an extended central cone. Viewed from the side, these Rudbeckia relatives resemble the sombreros worn by Mexican bandits in cowboy films.

Soil preference:Any well-drained, but not too dry

Aspect:Sun

Season of interest:Summer

Height and spread:60cm × 45m (2ft × 1ft 6in)

Companion plants:A delightful cottage garden plant whose shape contrasts well with campanulas, delphiniums or with perennial asters.

Lysimachia atropurpurea

Hardy biennial or shortlived perennial

A striking, if somewhat sparse growing species with pewter-suffused foliage when young and, during mid-summer, narrow spikes of deep purple-red flowers which contrast with the grey-green tones of the leaves. From the distance, the flowers look black and disappear, but close-to, especially if used as cut flowers, they are superb.

Soil preference:Fertile, free-draining

Aspect:Sun

Season of interest:Summer

Height and spread:45cm × 30cm (1ft 6in × 1 ft)

Companion plants:Best planted with light-coloured foliage plants such as Artemisia ludoviciana or Convolvulus cneorum so that the sombre blooms can make a strong contrast.

Oenothera biennis

Evening Primrose Biennial

Broad, pointed leaves form loose rosettes producing, in their second year, tall, somewhat lax stems with large pale yellow blooms that open at twilight and are spent by the following midday. May be a nuisance self-seeder, but a late summer delight.

Soil preference:Any

Aspect:Sun or part shade

Season of interest:Summer

Height and spread:1.2m × 45cm (4ft × 1ft 6in)

Companion plants:One to dot about or allow to come up where it will in an informal planting scheme. Especially good among the soft mauves, purples and blues of perennial asters or in a late season annual border.

Scabiosa atropurpurea

Mournful Widow, Egyptian Rose Biennial

Lobed or divided leaves and thin, branched stems carry, in summer and early autumn, a long succession of pincushion-like flowers in dusky maroon or near black. The form ‘Chile Black’ is dark crimson, ‘Chile Sauce’ is rose red and ‘Salmon Queen’ a deep salmon pink.

Soil preference:Any fertile soil

Aspect:Sun

Season of interest:Summer

Height and spread:90cm × 45cm (3ft × 1ft 6in)

Companion plants:Beautiful grown with summer annuals such as corn cockle or field poppies, and with taller ornamental grasses like Deschampsia.

Biennials for special effects

Eryngium giganteum ‘Miss Willmott’s Ghost’

short-lived perennial

A very large perennial with prickly leaves and stems. The leaves are suffused with silvery white and each dome-shaped, thistle-like flower carries a spiky ruff at its base. The common name arises from the habit of Edwardian garden guru Ellen Willmott who, presumptuously, scattered seeds of it in other people’s gardens.

Soil preference:Any fertile

Aspect:Sun or part shade

Season of interest:Summer, autumn

Height and spread:1.5m × 80cm (5ft × 2ft 8in)

Companion plants:Plants of great character, making strong focal points in mixed borders. Useful for lightening up dark evergreen shrubs at the back of borders, or to dot among tall perennials such as Verbena bonariensis and with big grasses.

Geranium maderense

Madeiran Cranesbill Tender biennial

Palmate leaves grow from a stumpy base, forming a large, impressive rosette. When the necessary size has been reached, a big branched flowerhead forms and erupts into a spectacular display of rich cerise to rosy purple flowers, each with a more intense eye. Once seed has formed, the plant dies. Must have winter protection.

Soil preference:Any not too dry, but well-drained

Aspect:Part shade

Season of interest:Summer

Height and spread:Up to 1.3m × 1m (4ft × 3ft 3in)

Companion plants:Best in a container in cold regions. Perfect in the company of ferns or of broad-leaved, shade-loving plants such as the larger hostas.

Meconopsis napaulensis

Technically a perennial but seldom survives flowering

As valued for the beautiful rosettes of felty lobed leaves, each one covered in rust-coloured hairs, as for the huge flower spikes which will grow well over 2m (6ft) before producing a generous supply of poppy flowers in pinkish red, purple or dusky blue.

Soil preference:Preferably lime-free, not too dry

Aspect:Shade or part shade