Cornus

Flowering Cornus (dogwood) trees are grown for their showy coloured bracts in late spring and early summer. Shrubby Cornus alba, C. sericea and C. sanguinea are grown for their vivid winter stem colour, while shrubby C.mas (the cornelian cherry) is grown for its winter flowers and summer fruits. This varied group of plants give great garden value.

Cornus alba  'Sibirica'

Cornus alba 'Sibirica'

Quick facts

Common name Dogwood, flowering dogwood
Botanical name Cornus
Group Shrub or tree
Flowering time Flowering dogwoods flower in late spring to early summer
Planting time October to March
Height and spread 3-8m (10-25ft) height and spread, but shrubs can be kept small by pruning
Aspect Full sun to partial shade
Hardiness Fully hardy to frost hardy
Difficulty Easy

Cultivation notes

Site and soil conditions

Shrubby dogwoods grown for their winter stem colour (Cornus alba, C. sericea and C. sanguinea cvs.) are unfussy about their soil conditions, but they are able to thrive in damp conditions where other shrubs might fail. C. controversa (the wedding cake tree), C. alternifolia (the pagoda dogwood), C. mas (the cornelian cherry) and C. officinalis are also tolerant of a range of soil conditions.

Flowering dogwoods Cornus florida, C. kousa, C. capitata and C. nuttallii do best in well-drained but fertile soil that is rich in organic matter and neutral to acid in pH. C. kousa (from Korea and Japan), is more tolerant of neutral to alkaline conditions than are the North American species C. florida and C. nuttallii.

The creeping dogwoodCornus canadensis, needs moist, acid soil conditions.

All Cornus species will tolerate full sun or partial shade, but those grown for their winter stem colour show better colour when grown in full sun.

Watering and feeding

Water thoroughly in dry spells, especially during the first two to five years after planting, during the establishment phase of growth. Top dress with a balanced granular or powdered fertiliser, such as Growmore or fish, blood and bone, in late winter to early spring, at a rate of 70g per sq m (2oz per sq yd). Supplement with a high potassium feed such as sulphate of potash in spring or summer if flowering seems poor, at 15g per sq m (½oz per sq yd). Mulch the root area with well-rotted organic matter in spring and/or autumn.

Pruning and training

Shrubby Cornus cultivars grown for their winter stem colour should be pruned back hard every year to encourage new growth, which has the best colour. This is called coppicing.

  • Traditionally, shrubby cornus were pruned in February or March
  • Recent case studies have shown that pruning annually in late March to mid-April (as the new growth is just beginning to develop) is preferable. This later pruning allows the winter display to be enjoyed, but doesn't currently appear to have negative consequences from bleeding or the cutting off of some new growth
  • It should be noted that less frequent pruning – every two to three years – is best where the growing conditions are poor and shady
  • Newly planted cornus often benefit from not being pruned for the first two to three years while they establish – the general rule of thumb is to begin pruning as normal once the plants are growing strongly

C. controversa and C. alternifolia need little pruning, developing their tiered shape naturally with time. Limit pruning to removal of lower branches as the tree grows in height, to create a clear trunk. There should be one topmost leading branch, and any side branches that compete with it should also be removed. Pruning, if needed, is best carried out between autumn and early spring, while the tree is dormant and leafless. Hard pruning is not tolerated and will spoil the shape of the tree.

C. kousa, C. florida and C. nutallii need very little pruning beyond the removal of lower branches as the tree matures to create a clear trunk. This is best done while the tree is dormant and leafless, between autumn and early spring. Dead wood may accumulate in the canopy, and can be removed after flowering. Hard pruning is not tolerated and may spoil the shape of the tree or result in dieback.

C. mas and C. officinalis can be thinned out in early summer, removing selected branches to display the flowers better on those remaining, and to allow light and air into the centre of the shrub. Overgrown specimens can be renovated by cutting back side branches to within two buds of the main framework branches.

Propagation

Species plants can be propagated from seed, but named cultivars will not come true to type from seed and are better propagated from hardwood or greenwood cuttings. Variegated cultivars of C. controversa (the wedding cake tree) and C. alternifolia (the pagoda dogwood) are usually grafted commercially in winter, but may also be propagated at home from cuttings.

Cultivar Selection

For winter stem colour
C. alba ‘Sibirica’ AGM: Bright red stems in winter, red autumn leaves
C. alba ‘Kesselringii’: Dark purple-black stems in winter, purple foliage year-round
C. sericea ‘Flaviramea’ AGM: Lime green winter stems
C. sanguinea ‘Midwinter Fire’: Yellow-orange-red winter stems

Flowering dogwoods
C. kousa ‘China Girl’: Small tree that flowers freely even when young; white bracts in early summer followed by strawberry-like fruits; purple autumn leaf colour
C. kousa ‘Miss Satomi’ AGM: Small tree with dark pink bracts in early summer followed by strawberry-like fruits; purple autumn leaf colour
C. mas: Large shrub with delicate yellow flowers in late winter and bright red fruits in late summer
C. macrophylla: Medium sized tree with broad, flat heads of tiny creamy flowers in late summer

Other dogwoods
C. controversa ‘Variegata’ AGM: Spreading tiered branches with leaves edged in white; known as the wedding cake tree because of its tiered branch structure

Links

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Problems

Cornus can suffer the specific disease Cornus anthracnose, but may also suffer from a range of common problems including honey fungus and Phytophthora root rot.


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