With their impressive flowers, magnolias are one of the most valuable ornamental trees in the spring garden. Once planted, they provide an abundance of flowers for decades, while also being low maintenance.
Besides various magnolias, the Magnoliaceae family also includes the tulip tree (Liriodendron) and is today considered the oldest family of flowering plants in the world. The family has existed for over 100 million years and all current angiosperms evolved from it – so all known deciduous trees, shrubs and grasses. Magnolias - which includes around 80 species worldwide - are characterized by primitive flowers with a cone-like pistil and a variable number of spirally arranged petals that are not fused together – this shows that they are still very closely related to the green leaves.
The natural range of today’s magnolia species is from East Asia to Central America. Archeological finds have shown that stately magnolias were also growing in Central European forests before the ice ages. However, the advance of the glaciers and low temperatures on the European continent caused them to die out.
Appearance and Growth
The American species tend to grow faster and can develop into large trees, while East Asian magnolias remain smaller and often flower before the leaves appear. As they are also slightly more frost-hardy than their American relatives, Asian species like the star magnolia (Magnolia stellata), the kobus magnolia (Magnolia kobus), and the lily magnolia (Magnolia liliiflora) are most relevant in European gardens. Furthermore, there are two hybrid groups in the form of the very popular saucer magnolia (Magnolia x soulangeana) and varieties of Loebner Magnolia (Magnolia x loebneri). A large-scale breeding program has been running in the USA for several decades. The goal is to create a new generation of early flowering and very hardy magnolia hybrids with yellow flowers by crossing different Asian magnolias with the American yellow flowering cucumber magnolia (Magnolia acuminata var. aurea). The first new varieties like ‘Butterflies’ and ‘Yellow Bird’ have already proven their worth in our gardens.
Depending on the species and variety, magnolias have broad, upright or very expansive growth and form light, loosely branched crowns. At just under ten foot, the star magnolia is one of the smallest representatives of the species and therefore a magnolia tree for small gardens. The tallest species in these parts is the cucumber magnolia (Magnolia acuminata), growing to a height of 80 foot. The bark of the magnolia tree is usually light gray to brown and has clearly visible, light lenticels on the one-year-old shoots. Most species have deciduous, alternate leaves and some, such as the frost-sensitive southern magnolia (Magnolia grandiflora), are even evergreen. The leaves tend to be quite large and are obovate to wide and oval. Just like the bark, they give off an intense, slightly pungent odor when ground down. In mid-March, the star magnolia is the first species to begin flowering, while the June-flowering Oyama magnolia (Magnolia sieboldii) is one of the latest. Depending on the species, the flowers vary in color from white and yellow to pink and rose red and are bowl to star-shaped. The fruit of the magnolia is a reddish brown, cucumber-like aggregate fruit, with black-brown seeds that resemble beans.
Magnolias have sensitive roots and prefer very loose soil that is rich in humus and nutrients and as evenly moist as possible. Prolonged dry periods can slow the plant’s growth and the leaves soon turn yellow. The location should be as sunny as possible and slightly sheltered due to the early flowering. The plant will still grow in partial shade, but this will result in far fewer flowers.
Where to plant
Magnolias are classic solitary specimens for spring gardens and go very well with rhododendrons. The saucer magnolia is a spreading tree that is often planted in parks due to its impressive flowers. Give the crown plenty of space so that it can spread uninterrupted. Magnolias go well in flower beds with any early bloomer, especially bulbous plants like daffodils (Galanthus), winter aconite (Eranthis), crocuses, lung wort (Pulmonaria), and sweet violet (Viola odorata). Avoid competitive perennials such as ground-covering species of geranium. They make life difficult for the sensitive roots of magnolia.
The star magnolia is also suitable for roof gardens, provided that you use large containers and ensure that it is watered consistently. The best option is to use an automatic drip irrigation system.
Cover the root area with bark humus after planting, and avoid any ground work so as not to disturb the sensitive roots which develop just below the surface.
Magnolias do not need regular pruning. It is best to let them grow undisturbed. Tree-like specimens can be trimmed after a few years if you want to underplant them or put a bench underneath.
Magnolias are generally planted in spring, as otherwise small, poorly rooted plants may experience problems in the first winter. The flowers of the saucer magnolia appear early and are therefore very susceptible to frost. It has proven useful to mulch the root area well in winter during ground frosts in order to delay soil warming and flowering in spring.
Hobby gardeners can only propagate magnolias by layering and by seed. Both methods require plenty of patience: It can take two years for the layers to produce enough roots, while the seeds sown immediately after harvesting often do not germinate until the second spring and even then are very erratic. Nurseries previously propagated garden varieties vegetatively by layering, but this is no longer commercially viable, since it takes two years for the roots to form and the mother plants require extensive care. Today, most magnolia cultivars are propagated from cuttings in a greenhouse, although this requires a high degree of technical effort. The new magnolia cultivars from the USA are predominantly obtained from meristem culture, as large quantities can be produced within just a few years.
Diseases and Pests
Magnolias are largely resistant to diseases and pests. In rare cases, they can be affected by bacterial leaf spot (Pseudomonas).
Frequently Asked Questions
When do magnolias flower?
Different species flower at different times. The star magnolia produces flowers as early as March, while the Oyama magnolia blooms in June.
How tall do magnolias grow?
Depending on the species or variety, magnolias can grow to very different sizes. The American species generally grow taller than the Asian ones. But hybrids can also reach relatively big sizes. The saucer magnolia, which is very popular in this country, can develop into a 30-foot tall tree.
When can you plant magnolias?
Like most trees, magnolias can be planted in both early spring and fall.
What kind of soil is suitable for magnolias?
Magnolias prefer very loose, nutrient and humus-rich soil that is evenly moist.
When can you prune magnolias?
Magnolias do not normally need pruning. However, if you want to thin the crown out a little, it’s best to do this in late summer.
Which magnolias are suitable for small gardens?
The star magnolia is one of the smallest varieties. But the Oyama magnolia, the lily magnolia, and the magnolia hybrids ‘Genie’, ‘Sun Spire’ and ‘Sentinel’ are perfect for small gardens.