Cornus: the best flowering dogwoods

By Klaudia Mihalova

Published: Wednesday, 05 October 2022 at 12:00 am

Cornus is a genus for all seasons. Those grown for their leaves are some of the most beautiful foliage shrubs. Dogwoods grown for the colour of their stems light up the winter garden. Flowering dogwoods wisely hold back their floriferous performance until early summer, after any possible
competition from our more familiar flowering trees.

When it comes to summer flowering trees and large shrubs there is nothing to touch flowering dogwoods. There are few more breathtaking sights than a flowering dogwood in full bloom. I first fell in love with Cornus ‘Porlock’ in the Sir Harold Hillier Gardens, Hampshire. The way the blooms cascaded down the branches, the poise of the flowers, the way they fluttered in the breeze, how they gazed upwards, avoiding the eye, but teasing and tantalising. Its beauty was best admired by grasping a branch and holding it down to admire those creamy bracts, four of them arranged as a flattened star around each dark bobble of tiny flowers. In autumn, strawberry-like fruits weighed down the branches; hardly delicious but edible and very tempting.

CORNUS: IN BRIEF

What Known as dogwoods or cornels there are around 60 species of Cornus, ranging from low, creeping, sub shrubs to large trees. Many have given rise to valuable garden ornamentals grown for flowers, foliage or winter stems.

Origins North America, Europe and Asia. They are mostly hardy, woody plants from cool, temperate regions.

Season The flowering dogwoods bloom from late spring to midsummer. Those grown for foliage are deciduous, but are beautiful in leaf from spring to autumn. Cornus grown for stem colour are great in winter.

Size From 5 x 30cm (Cornus canadensis) to 8 x 6m (Cornus controversa ‘Variegata’, although most grow to around 3-5m.

Conditions Most well-drained, reasonably moist, fertile soils. The flowering dogwoods favour acid to neutral conditions.

The cultivars of C. kousa are often collectively referred to as Chinese dogwoods, although many originate from Japan and Korea. C. kousa var. chinensis ‘China Girl’ is deservedly popular and has the advantage of large flower heads produced on young plants; some cultivars take a few years to bloom with any enthusiasm. C. kousa ‘Teutonia’ is another large, flowering form with immaculate flower heads of rich cream. I have shown this in recent years at
RHS Chelsea Flower Show and it has always proved to be a star of the show.

The North American dogwoods, cultivars of C. florida and C. nuttallii, are less popular because of their susceptibility to the fungal disease cornus anthracnose. A pity, as most mature to form wonderful, pagoda-like small trees with elegant branches and upturned twigs. In winter, flowerbuds are enclosed by the immature bracts on the bare branches, appearing like tiny finials at the end of every twig. As the blooms develop the bracts remain joined at the tips before they pop open.

The hybridisation of flowering dogwoods has led to the development of some spectacular flowering shrubs. C. Venus, bred in the USA, has caused a stir with its massive creamy-white flower heads, which are produced freely, even on young plants. The Stellar series of hybrid flowering dogwoods, exhibit similar flower quality and disease resistance, and will hopefully encourage more to plant these wonderful shrubs and trees.

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How to grow cornus

Flowering dogwoods favour neutral to acid, reasonably moist, but well-drained fertile soil, with plenty of organic matter. However, they are more tolerant than generally thought and often succeed in alkaline conditions if mulched well with organic compost. I have grown dogwood successfully on poor sandy soil and in containers using loam-based growing media.

Cornus are at their best with some light shade and shelter from deciduous trees; they thrive in open woodland settings. Many, such as Cornus ‘Porlock’ and Cornus florida ‘Cherokee Chief’, make splendid flowering trees for small gardens. Flowering dogwoods are best planted as young, container-grown plants from October to March.

Young plants are not particularly attractive, giving little idea of the glorious subjects they will become; which puts many off planting them.