Magnolias: How To Care For Them!

The Magnolia family (Magnoliaceae), which includes the various magnolias as well as the tulip tree (Liriodendron), is, according to current knowledge, the oldest family of flowering plants on earth. It already existed more than 100 million years ago and all of today’s angiosperms have evolved from it – i.e. all known deciduous shrubs, perennials and grasses. A distinguishing feature of magnolias, of which there are about 80 species worldwide, is the primitive flower structure with a cone-shaped pistil and a variable number of helically arranged petals that are not fused with each other – this shows their still very close relationship with the green foliage.

Today’s magnolia species have their distribution areas in East Asia and North and Central America. Archaeological findings have shown that stately magnolias also grew in Central European forests before the ice ages. However, they became extinct with the advance of the glaciers and the low temperatures on the European continent.

Appearance and growth


The American species tend to grow more vigorously and can develop into large trees, while the East Asian ones remain smaller and often bloom before the leaves emerge. Because they are also somewhat more frost hardy than their American relatives, Asians such as the Kobushi magnolia (Magnolia kobus), the star magnolia (Magnolia stellata) and the lily-flowered magnolia (Magnolia liliiflora) are most important in European gardens. A beautiful hybrid selected from the latter as well as a pink star magnolia ‘Rosea’ is the magnolia ‘Susan’ with compact growth and flowers in deep magenta shades. In addition, there are two hybrid groups, the extremely popular tulip magnolia (Magnolia x soulangeana), which is a cross between the lily magnolia (Magnolia denudata) and the purple magnolia (Magnolia liliiflora), and the Löbners magnolia (Magnolia x loebneri) varieties. In the USA, a large-scale breeding program has been underway for several decades. The goal is to create a new generation of early-flowering and good hardy hybrid magnolias with yellow flowers by crossing various Asian magnolias with the American yellow-flowering cucumber magnolia (Magnolia acuminata var. aurea). The first new varieties such as ‘Butterflies’ and ‘Yellow Bird’ have already proven themselves in our gardens.

Magnolien-Hybride ‘Yellow Bird’

Depending on the species and variety, the various magnolias grow broadly upright or very spreading and form light, loosely branched crowns. Among the smallest representatives and thus among the magnolia trees for small gardens is the star magnolia with a height of barely three meters. The tallest in our latitudes is the cucumber magnolia (Magnolia acuminata) with 25 meters. The bark of magnolias is usually light gray to brown and often covered with clearly visible, light-colored lenticels on the one-year-old shoots. The foliage is deciduous and alternate in most species, and evergreen in some, such as the frost-sensitive Evergreen Magnolia (Magnolia grandiflora).

The leaves are mostly quite large and obovate to broad-ovate. When rubbed, they give off an intense, slightly pungent odor, as does the bark. The first species to show its flowers is the Star Magnolia, starting in mid-March, while the Summer Magnolia (Magnolia sieboldii), which blooms in June, is among the latest. Depending on the species, the flower colors vary from white to yellow and pink to rose-red, and the flower shapes from tulip-shaped to star-shaped. The fruits of the woody plants are reddish-brown, cucumber-like aggregate fruits with bean-like, usually blackish-brown seeds. An attractive rarity is the well-hardy umbrella magnolia (Magnolia tripetala).

Magnolias have a delicate root system and prefer humus- and nutrient-rich, very loose soil with as even moisture as possible. In prolonged drought, they quickly turn yellow leaves and stop growing. The location should be as sunny as possible and somewhat protected because of the early flowering. In partial shade, the woody plants also grow, but the flower set is significantly lower.

Use


Magnolias are classic specimen shrubs for the spring garden and go very well with rhododendrons. The spreading tulip magnolia, in particular, is also popular for planting in parks because of its impressive abundance of flowers. Be sure to give the crowns enough room to spread undisturbed. Good bedding partners are all early bloomers, primarily bulbous flowers such as daffodils (Galanthus), winter bulbs (Eranthis), crocus (Crocus), lungworts (Pulmonaria) and scented violets (Viola odorata). Avoid competitive perennials such as some ground-covering cranesbill species (Geranium). They often make life difficult for the sensitive magnolia roots.

Star magnolia is also suitable for rooftop gardens if you use large planters and can ensure even watering. Automatic drip irrigation is best.

Sternmagnolie

Plant
Cover the root zone with bark humus after planting and refrain from any soil work to avoid disturbing the delicate, near-surface roots as they develop.

Pruning
Magnolias do not need regular pruning. They are best left to grow undisturbed. Tree-like representatives can be pruned up over the years to plant underneath or to create a seating area underneath.

Winter protection


Always plant magnolias in the spring. Small, poorly rooted plants may otherwise have problems in the first winter. The flowers of the tulip magnolia are very susceptible to frost because of their early shoots. Here it has proven useful to mulch the root area thickly in winter when the ground is frosty, in order to delay warming and thus flowering somewhat in spring.

Magnolie Samen

Propagation
For amateur gardeners propagation of magnolias is possible only by lowering and sowing. However, a lot of patience is needed for both methods: the cuttings have formed sufficient roots only after two years, the seeds sown immediately after harvesting often germinate only in the spring after next and then also very unevenly.

Vegetative propagation of the garden forms used to be done in nurseries also by lowering plants, but this is no longer economical because of the two-year rooting period and the costly maintenance of the mother plant quarters. Nowadays, most magnolia cultivars are propagated in the greenhouse by cuttings, but this requires a great deal of technical effort. The new magnolia cultivars from the USA are mainly from meristem culture in order to be able to offer large numbers within a few years.

Diseases and pests
Magnolias are largely resistant to plant diseases and pests. In rare cases, bacterial leaf spots (Pseudomonas) can occur.

Frequently asked questions

When does the magnolia bloom?


The different species have different flowering times. Star magnolia opens its flowers already from March, and summer magnolia – only in June.

How big does the magnolia grow?


Depending on the species and variety, magnolias can grow quite different sizes. Basically, the American species grow larger than the Asian ones. Hybrids can also become relatively large. The tulip magnolia, which is so popular in our region, can grow to a tree nine meters high.

When can you plant a magnolia?


Magnolias, like most trees, can be planted both in early spring and autumn.

What soil is suitable for magnolia?


Magnolias prefer a very loose soil, rich in nutrients and humus, evenly moist.

When can you cut a magnolia?


Normally, magnolias do not require pruning. However, if you want to thin out the crown, you should prune in late summer.

Which magnolia is suitable for a small garden?


One of the smallest species is the star magnolia. But also the summer magnolia, purple magnolia or magnolia hybrids ‘Genie’, ‘Sun Spire’ or ‘Sentinel’ are suitable for a small garden.

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