Magnolia: the Magnificent Heralder of Spring
Magnolia is a large, ancient genus with fossilised specimens dating back over 20 million years ago. The genus is named after Pierre Magnol, a 17th-century botanist. In our opinion, nothing beats the sight of a magnolia in full flower. Like sign posts to the beginning of the spring season,
Site and Conditions
For best growth and flowering, site magnolias in full sun in fertile, moist garden soil.
On dry, alkaline soils, consider Magnolia grandiflora and M. delavayi. On moist, alkaline soils try M. kobus, M. x loebneri, M. seiboldii, M. stellata and M. wilsonii. M. grandiflora and M. virginiana will tolerate wet soils.
Some later-flowering deciduous species, such as M. wilsonii and M. sieboldii, will enjoy light dappled shade.
A sheltered site is important. M. grandiflora and M. delavayi grow best on a warm wall and may not survive in regions where the temperature drops below -5°C (23°F). Frosts can damage flowers in spring and evergreen foliage in autumn.
M. grandiflora is not especially "windfirm" and may need staking when planted in the open, even when quite mature.
Magnolias, especially evergreen ones, are commonly grown against walls. Despite this, reports of damage to buildings by magnolias are uncommon.
Plant as for other trees.
Magnolias can be grown in containers.
Pruning and Training
Pruning is seldom required, with the following exceptions:
Shape trees at planting time by removing weak and badly placed growth and tipping back long shoots.
Heavy pruning of mature magnolias can induce water shoots (long, vertical, vigorous shoots) and dieback. Routine pruning is therefore usually restricted to removing deadwood and water shoots.
When pruning to limit size, aim to maintain an open, balanced crown by thinning out stems to the trunk or to a side-shoot. Stage the pruning over several years to avoid stressing the tree.
Renovation should also be done over two or three years, and trees can be slow to recover.
Prune branches back to a natural fork to avoid leaving unsightly stubs.
Cuts bleed if pruned in late winter or early spring, so pruning should only be done between mid-summer and early autumn.
Young trees need no pruning other than the shortening of lengthy, young branches and the removal of lower boughs where a bare stem is desired.
Hard pruning is tolerated when renovation or repair of storm damage is required. Cut back to the main framework or even beyond. However, it is safest to spread this work over several years.
Otherwise, prune free-standing trees in spring, as growth begins, and wall-trained specimens in summer.
The evergreen Magnolia grandiflora flowers and grows particularly well if trained against a sunny wall.
Wall-trained trees are trained by tying them to wires or other supports, initially tying-in shoots at 45 degrees, then lowering them to the horizontal the following season.
Regular pruning consists of removing shoots growing towards the wall and shortening outward-growing ones to one or two leaves.
If these outward-growing shoots bear flower buds, pruning can be delayed until immediately after flowering.