Cornus

These versatile shrubs are best known for their winter colour but they can offer so much more.

Cornus Kousa chinensis - photo: HW
Cornus Kousa chinensis - photo: HW

Dogwoods are best known for their colourful winter stems but they are also versatile shrubs and trees grown for their showy bracts, leaf variegation or attractive habit. The winter dogwoods offer reliable stem colour, especially when cut back or pollarded in spring to encourage masses of -juvenile shoots. Costing as little as 20p a transplant when bought in bulk, they make large border or waterside plantings very affordable.

Two of the best winter-stem varieties are the red Cornus alba ‘Sibirica’ Award of Garden Merit (AGM) and yellow-stemmed C. sericea ‘Flaviramea’ AGM. C. alba ‘Kesselringii’, with purple to black stems, and C. sanguinea ‘Midwinter Fire’, which has orange, red and yellow stems, are also popular.

Landscapers mix the different coloured species to great effect. To maintain the coloured-stemmed varieties you need to prune them hard every two to three years in spring and grow them in full sun to promote the brightest reds and yellows.

There are variegated varieties to make winter-interest borders look good through summer, such as the white- and green-leaved C. alba ‘Elegantissima’ AGM, which has red -winter stems.

Dogwoods are mainly deciduous trees and shrubs growing across northern temperate areas. C. sanguinea is native to the UK and is grown in mixed deciduous native hedgerows. It is popular for its red winter stems and berries, which attract birds.

There are roughly 45 species, from which many fine ornamental plants have been bred. C. alternifolia ‘Argentea’ AGM and C. controversa ‘Varie-gata’ AGM, known as the “wedding-cake tree”, have tiered branches and white and green leaves, and make impressive lawn or border specimens. They are both slow-growing and have intermediate stems or twigs that grow between the tiers, which need to be removed at regular intervals.

Those varieties are known as flowering dogwoods and have showy, pink to white bracts in late spring or early summer. They are mainly bred from two species, C. florida  and C. kousa, and are suitable for planting in acid soils and areas with partial shade.
Most other dogwoods tolerate a range of soils, except for the low-growing ground cover C. canadensis  AGM, which prefers a moist, acid soil and shade.

Cornus can be prone to attack by anthracnoses or fungi, which reduce the plants’ vigour but do not necessarily cause significant damage. Growers recommend thinning the canopy to increase air movement and planting disease-resistant varieties.

There are many ways to increase stock of dogwood: by seed, soft or hardwood cuttings, or — in the case of the ground-covering C. canadensis AGM — by division.

What the specialists say

Robin Wallis, sales manager, Chichester Trees & Shrubs, Hampshire
“A good ground-cover plant for lime-free soil is C. canadensis Award of Garden Merit (AGM), but it’s slow-growing so it’s expensive. My favourite trees for drama are C. controversa ‘Variegata’ AGM and C. alternifolia ‘Argentea’ AGM. Both have a lovely habit and great foliage.
“My tip when planting Cornus is to spend £20 on improving the soil. These trees have deep roots and like rich living, so it’s much better to dig a pit as you would do for a tree with a 14-16cm girth and really enrich the hole with good compost.
“Another good tip is that C. sanguinea ‘Midwinter Fire’ is one of the few suitable for drier soils. Most of the others prefer moist soils.
“The flowering dogwoods are lovely. C. ‘Eddie’s White Wonder’ AGM has big flowers, C. kousa var. chinensis AGM has horizontal branches and white bracts, and C. ‘Norman Hadden’ AGM is semi-evergreen with white bracts in spring. These are all good for acid soils.
“Multi-coloured-leaved varieties like C. florida ‘Cherokee Sunset’ are nice but can be hard to fit into landscaping schemes colour-wise.”

John Hardy, sales executive, Crowders Nurseries, Lincolnshire “We sell lots of the red-stemmed C. alba ‘Sibirica’ AGM and yellow-stemmed C. sericea ‘Flaviramea’ AGM because their contrasting colours are so effective in winter. They are always popular in landscaping schemes and are also in demand from garden centres.
“I think coppiced Cornus is very useful because contractors can use their own discretion when it comes to maintenance. It doesn’t need much looking after — most people tend to prune it before planting to encourage more stems to grow, then prune it just once a year after that.
“We produce a lot of the bare-rooted hedging plant C. sanguinea or common dogwood that is used in mixed plantations of native hedging with plants like Crataegus and Prunus spinosa. It adds a contrasting colour to the hedgerows although it hasn’t got really reddish winter stems like the others, more greenish with a red flush.
“We sell the wedding-cake tree, C. controversa ‘Variegata’ AGM, but it’s slow-growing and therefore expensive. C. mas is popular because it’s quite similar to a witch hazel (Hamamelis) with yellow flowers on bare stems in February.”

In practice

Jason Lock, landscape director, Notcutts Landscapes, Suffolk
“We principally use winter-stem varieties like C. sanguinea ‘Midwinter Fire’, which has red to amber-yellow variation on the stems. We also use the red-stemmed C. alba ‘Sibirica’ AGM. Planted together these make a striking combination.
“The other variety I use quite a bit is C. sericea ‘Flaviramea’ AGM, which has lovely rich lime-green stems. But you’ve got to be careful where you plant it as it spreads easily by suckers.
“We’ve just done a job planting a C. controversa ‘Variegata’ AGM as a lawn specimen. They are expensive and I don’t think small ones represent good value for money — it’s better to spend a bit more and get a good specimen.”

Species and cultivars

•    C. alba ‘Aurea’ Award of Garden Merit (AGM) is a deciduous shrub with bright red stems in winter and attractive golden leaves that are red-tinged in autumn. It produces white flowers in late spring and blue-tinged white fruit.
•    C. alba ‘Elegantissima’ AGM has red bark and grey-green leaves with white margins. It has many bright red winter stems when regularly pollarded and white spring flowers followed by white, blue-tinged fruit.
•    C. alba ‘Kesselringii’ is a winter-stem variety with purple-black stems.
•    C. alba ‘Sibirica’ AGM is deciduous and has red bark. It is less robust than the other cultivars. It produces bright red winter shoots if pollarded.
•    C. alba ‘Spaethii’ AGM is deciduous with red bark, red winter stems and golden-variegated leaves. Blue-tinged fruit follows white flowers.
•    C. alternifolia ‘Argentea’ AGM is also sold as ‘Variegata’. It grows to 3m tall with a spread of 2.5m and has tiered branches.
•    C. canadensis AGM is a perennial ground-cover plant with an indefinite spread that grows to a height of 15cm. It has green flowers with white or pink-flushed bracts in summer followed by bright red fruit. It requires moist, acid soil.
•    C. controversa ‘Variegata’ AGM is known as the “wedding-cake tree”, with tiered branches and a cream variegation on the leaf. It is a decidu-ous specimen tree growing slowly to 8m by 8m.
•    C. ‘Eddie’s White Wonder’ AGM is a cross between C. nuttallii and C. florida. It has abundant flowers and forms a shrub growing to 6m tall by 5m wide with white flower bracts in early summer followed by attractive autumn foliage colour. It thrives in acid soil.
•    C. florida ‘Cherokee Chief’ AGM is a deciduous tree or shrub that grows to 6m by 8m. It has good autumn leaf colour and striking, dark pink bracts in early summer. It needs acid soil.
•    C. kousa var. chinensis AGM has flaky bark and good autumn colour. It reaches 7m with a 5m spread. In early summer it produces green flowers surrounded by white to red-pink bracts.
•    C. kousa ‘Satomi’ AGM has dark pink bracts and red-purple autumn foliage.
•    C. mas ‘Golden Glory’ AGM has umbels of yellow flowers in late winter on leafless stems, followed by bright red summer fruit. It is a spreading, deciduous shrub or small tree growing to 5m x 5m.
•    C. mas ‘Variegata’ AGM is a compact, variegated cultivar growing to 2.5m and bearing plenty of red fruit.
•    C. ‘Norman Hadden’ AGM is a semi-evergreen tree growing to 8m x 8m with abundant flowers surrounded by cream to dark pink bracts, followed by pendent, strawberry-like red fruit.
•    C. sanguinea ‘Midwinter Fire’ has bright orange-yellow-red winter stems and is a popular pollarding cultivar. White flowers are borne in summer, followed by black fruit.
•    C. sericea ‘Flaviramea’ AGM has bright yellow-green winter shoots and is often coppiced.


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