Showy bracts
The impression of fluttering papery blooms is created by the four bracts that enclose a tiny flower. Opening after the leaves have emerged in spring, these bracts may resemble petals, but are in fact modified leaves. Varying in size from 1-3in (2.5-7.5cm) long, the largest can appear out of proportion on young cultivars such as ‘China Girl’. Here, they emerge small and green, only to gradually enlarge and turn creamy white over time. The bracts also vary in shape. On the species plant Cornus kousa, they are white and shaped like a rounded lance. Those on cultivars vary from long and narrow to broad and overlapping. On ‘Avalanche’, the bracts are so tightly packed together that the tree can be almost entirely smothered. A momentary impression is created of viewing the tree through a snowstorm. Bracts range in colour from pure white to cream, sometimes tinged with green, while cultivars such as ‘John Slocock’ develop pink streaks with age. There have been a number of recent introductions of pink-bracted cultivars. Some are hard to distinguish from the long-established favourites, ‘Miss Satomi’ and ‘Beni-fuji’, which has among the deepest reddish-pink bracts. All pink forms keep their colour best in cooler summer climates. “The richest pinks emerge in full sun, tending to fade in shadier conditions. ‘Miss Satomi’ can turn almost white,” adds Ed. In comparison to the eye-catching bracts, the true flowers are small, dark and inconspicuous, with minute petals varying from green to brown. “Nonetheless, they still attract
many insects, such as bees and hoverflies,” he says. Each flower is held singly on an erect stalk. These vary in height from stems that are less than ½in (1cm) long to a finger’s length which hold the flowers elegantly aloft. Some cultivars, such as ‘Trinity Star’, produce flowers intermittently all summer long.
Varied foliage
Kousa dogwoods prefer moist but well-drained soil that ranges from neutral to acidic. All flower most abundantly in full sun, but also grow healthily in partial shade. The more delicate variegated forms need shade from searing sun that scorches their leaves. Dogwood leaves unfurl in spring, wonderfully fresh with lustrous green upper surfaces and lighter green undersides that have downy tufts of hair. Approximately 4in (10cm) long and slightly less than half as wide, the leaf shape varies from narrow
to slightly oval, sometimes with wavy margins or recurving. There are beautiful colour variations. ‘Akatsuki’ has green leaves with white margins flushed pink, while ‘Gold Star’ has striking gold centres to each leaf. ‘Sunsplash’ has a gold variegation, and ‘Blue Shadow’ has deep blue-green foliage.
Planting and cultivation
Flowering dogwoods are ideal specimen trees to plant in light woodland or in the centre of a lawn, where the balanced form looks good from every angle. Being deciduous with an open habit, dappled sunlight reaches the ground beneath. These ornamental trees should be carefully spaced to allow sufficient space to grow into. “Kousa dogwoods need minimal pruning, and we don’t touch them except on rare occasions, to snip back any wayward branches,” says Ed. “They are virtually trouble-free, undemanding plants that flower for weeks on end.” Providing the ground does not waterlog, flowering dogwoods tolerate heavy soils reasonably well. The ground needs to be thoroughly dug over to break up compacted soil, before being conditioned with compost. “Kousas should be planted slightly proud, elevated above the soil level, to help them establish,” explains Ed. He finds they self-seed prolifically in gravel paths, and is planting some chance seedlings in out-of-the-way places, to see how they develop. “Some are now approximately 6½ft (2m) tall, but there’s nothing yet that is an improvement on the parent,” he says. New plants can also be created from softwood cuttings that are taken shortly after flowering. A healthy 5in (12cm) long stem is cut and the bottom pair of leaves removed before dipping into rooting hormone. The stem is inserted into a small pot of rooting compost and moistened. The pot is then covered with a small plastic bag, tied into place with string.
This keeps cuttings warm and humid and prevents wilting. Cuttings should develop roots within six weeks and can be tested by checking whether or not the stem resists a gentle tug. Once the bag is removed, the tiny plant is kept moist, in a sunny window. It is then repotted when the cutting outgrows its container. Most named cultivars are grafted onto the rootstock of the Chinese dogwood. Dogwoods are shallow-rooted and susceptible to drought and root damage. The best companion plants are those that do not compete for moisture and nutrients, for example daffodil and tulip bulbs for spring. Ground cover, with shallow roots and a moderate growth rate, such as bugle, periwinkle, lilyturf, cranesbill and dead nettle, are also suitable. Dogwoods are also susceptible to disease entering through damaged bark. It is best to leave a clear circle of at least 3ft (1m) in diameter immediately round the trunk to prevent damage from mowers. In the right place, where they can flourish, these small but spectacular trees will bring a profusion of colour and lush greenery to enjoy. Full of promise as they burst into life in spring, they add colour, character and interest as they respond to the changing seasons.
“The budding twigs spread out their fan, To catch the breezy air; And I must think, do all I can, That there was pleasure there”
CONTACT
The National Collection of Cornus, Newby Hall, Ripon, North Yorkshire HG4 5AE. Tel 01423 322583 www.newbyhall.com
William Wordsworth, ‘Lines Written in Early Spring’