Plant Profile: Lily Magnolia (Magnolia liliflora)

Magnolia (Magnolia liliflora nigra x veicthii) 'Raspberry Ice'
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The lily magnolia is a large deciduous shrub (or small tree) that sports profuse pink or reddish-purple blossoms in April and early May, just before the leaves appear. As one of the smaller magnolias, it is popular for informal screens or hedges, or as a specimen plant grown for its spring flower display.

Description

Lily magnolia grows to a mature height of 8 to 12 feet with a similar spread. It has a compact, rounded form, and produces a massive display of lily-shaped pink or reddish-purple flowers with six or seven petals, with each petal 3 to 4 inches long. The flowers are sometimes followed by cone-shaped purple or brown fruit, called follicles. As with other magnolia species, pollination is facilitated by beetles.

As the flowers fade, dark-green elliptical-shaped leaves appear. The fall foliage is not showy.

Botanical Information

Lily magnolia is native to southwest China, but has been cultivated across all of China and Japan for several centuries. Its taxonomical name is Magnolia liliflora (sometimes spelled lilliflora); the name refers to the lily-like shape of the flowers. Additional common names include Japanese magnolia, Mulan magnolia, purple magnolia, red magnolia, and tulip magnolia. The species form is often planted in landscape applications, though the most popular variety is one of the cultivars, Magnolia liliflora 'Nigra.'

The lily magnolia is one of the parent plants of an extremely popular hybrid, the saucer magnolia (Magnolia. × soulangeana). The other parent is Yulan magnolia (Magnolia denudata).

The species form of lily magnolia performs well in USDA hardiness zones 7 to 10, but the popular 'Nigra" cultivar is suited for zones 5 to 9.

Landscape Uses

Lily magnolia is most often grown as a specimen or accent plant in sunny areas, and is also good in group plantings or as an informal hedge or screen. The plant is moderately drought tolerant once the roots have had a chance to firmly anchor themselves after several years.

Growing Lily Magnolia

For best flowering, lily magnolia requires a site with full sun, though it also grows adequately in partial shade. The plant does best in moist, rich soils that are slightly acidic and which drain well. Heavy soils should be amended with peat moss or compost before planting. Lily magnolia is best planted in a semi-sheltered area that is protected from strong winds and cold temperatures. Avoid southern exposures where the buds may open too early in spring.

Water the shrub regularly throughout the year for the first few years, and cover the root zone with mulch to balance out soil moisture levels and temperatures. Once established, they are are moderately tolerant of dry conditions.

Magnolias do not respond well to severe pruning, but when it becomes overgrown or when there are dead or damaged branches, prune the shrub immediately after it flowers. If you prune too late, it will reduce flowering the following spring.

You can propagate this magnolia by taking cuttings or planting the seeds. If you have planted a cultivated variety, the plants resulting from the seeds may be different from the parent plant.

Recommended Cultivars

  • 'Nigra' has much darker purple flowers than the species form. USDA hardiness zones 5 to 9.
  • ‘O'Neil’ grows to 15 feet with dark purple flowers. Hardy in USDA zones 6 to 9.
  • 'Gracilis' is variety that is not quite as wide as the species. The leaves are also narrower.

'Nigra' is often crossed with other Magnolia species to produce new hybrids. For example, the U.S. National Arboretum created eight different varieties by crossing 'Nigra' with Magnolia stellata 'Rosea'. They are collectively called "The Girls" since they were given female names: 'Ann', 'Betty', 'Jane', 'Judy', 'Pinkie', 'Randy', 'Ricki' and 'Susan'.

Interested gardeners might want to look for a hybrid called 'Star Wars'. It is produced by crossing 'Nigra' with Campbell's magnolia (Magnolia campbellii).

Problems

Lily magnolia is a relatively problem-free shrub, and those problems that do occur are rarely life-threatening.

  • Magnolia scale insects (Neolecanium cornuparvum) suck out sap from the stems. Encourage ladybugs to visit your garden as they will snack on the scales and help remedy the problem to some degree. Horticultural and dormant oils can be used at different stages in the life cycle, though they will not be so effective against adults that have formed a wax barrier on their bodies.
  • Black sooty mold can form on plants that are infested with the magnolia scale. They drop a sugary substance called honeydew that the mold grows on. Control the scales to help control the mold problem.
  • Powdery mildew is another fungal problem that can crop up, especially in humid conditions, but it rarely kills the plant. To reduce powdery mildew, prune to improve air circulation. Keep area around the tree free of debris. Spraying the shrub with water early in the day may help dislodge mold spores. Fungicides applied early in the season may also prevent mildew.