Magnolia x soulangeana Seeds | Saucer Magnolia

Goblet-shaped pink and white flowers opening on bare branches of a saucer magnolia — Saucer Magnolia (*Magnolia x soulangeana*): Magnoliaceae, a garden hybrid of *M. denudata* and *M. liliiflora*.

LATIN NAME: Magnolia x soulangeana

COMMON NAME: Saucer Magnolia

Plant Profile

Saucer magnolia is a garden hybrid, and almost everything a grower needs to know about its flowers and its faults follows from that fact. It arose in a French garden in the 1820s, from a cross between Magnolia denudata and Magnolia liliiflora, and it has been in cultivation ever since without ever becoming a wild plant. The flowers are the reason: large, goblet-shaped, white flushed with pink at the base and often deeper pink outside, opening on bare wood in early spring before the leaves. Each flower is a cup of fleshy tepals that opens wide and then reflexes, and a mature tree in full bloom is one of the sights of the temperate spring. It grows as a broad, low-branched small tree, five to nine metres, with large obovate leaves and a smooth grey trunk. The flowering is early enough that a hard frost can brown the whole display in a single night.

Science & Biotechnology

As a hybrid, Magnolia x soulangeana is usually treated as sterile or nearly so, and the seed that does set segregates widely, so a batch of seedlings will produce a range of flower colours and forms, few of them equal to the parent. That is why the trade propagates named clones by cuttings, by grafting onto Magnolia kobus or M. acuminata rootstock, and increasingly by tissue culture. The cross sits within subsection Yulania, the deciduous magnolias, whose flowers are pollinated by beetles that feed on the pollen and the fleshy tepals; the flowers open before the leaves precisely so the beetles can find them. The hybrid shows heterosis in growth rate and flower size, and it also shows the weakness of both parents in a late frost, since the buds have no dormancy deep enough to wait. Cytology is complicated by the parentage, and fertility varies between clones.

Uses & Benefits

This is an ornamental tree almost without other uses. It is planted as a lawn specimen, in a courtyard where the spring display can be seen from a window, and in sheltered gardens where the flowers escape the frost. The tepals are thick and hold well when cut, though they bruise easily. The wood is soft and of no value, and the bark has none of the medicinal standing of Magnolia officinalis, which is the source of Hou Po. The tree’s real contribution is seasonal: two weeks in April when nothing else is doing anything comparable, followed by clean summer foliage and, in some clones, a second sporadic flush in late summer. It is also a parent of further hybrids, and the saucer magnolias as a group now include a wide range of named forms.

Growing from Seed

Sow fresh seed in autumn, after cleaning off the red fleshy coat, which inhibits germination and attracts mould; the seed is short-lived and must not be allowed to dry out. Sow two centimetres deep in a light, acid mix, keep at 15 to 20 degrees, and expect germination in six to twelve weeks, sometimes the following spring. The seedlings will not come true, so grow them as a gamble rather than as a crop. Pot on carefully, because magnolias have fleshy brittle roots and resent disturbance. Plant out in spring in deep, humus-rich, lime-free soil, in sun or light shade with shelter from late frost, and mulch widely. Do not cultivate around the root zone, and water through the first two summers.

Our Take

Grow it for two weeks of spring and accept the rest of the year as foliage. Buy a named clone if you want the flower colour, because seed will give you a mixture.

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