I saw my first magnolia flower of the season earlier this month, a solitary, ghostly-white, cup-shaped bloom unfurling high on the bare branches of a tree growing in a sheltered Dublin woodland garden. Defiantly beautiful on a cold and blustery day, it was a powerful sign that spring had finally arrived.
As an ancient angiosperm that’s believed to have emerged in the Cretaceous period some 95 million years ago, this exquisite genus of predominantly spring-flowering woody plants has a fascinating history. Those thick, silky petals, for example, are an evolutionary response to the fact that the magnolia first came into existence at a point in time when there were no bees to pollinate its flowers. Instead, it relied upon flightless beetles for that role, requiring its waxy blooms to be sturdy enough to bear their weight.
As a genus, it’s also bewilderingly complex to the point where taxonomists struggle to agree on the number of species of magnolia let alone the many hybrids. Even the story of its geographical origins is murky. The ancestors of the plants growing in Irish gardens today originated in parts of China, Japan, Korea and the US. But intriguingly magnolias were much more widespread in the very distant past before the Ice Age dramatically reduced their geographical range. Most definitely non-native, we can thank the derring-do plant-hunters as well as the brilliant nursery owners of the 19th and 20th centuries for these exceptionally lovely spring-flowering plants’ introduction into European gardens.
Typically best-suited to mild, sheltered but open woodland with a humus-rich, neutral to slightly acidic, damp but free-draining soil – there’s a list! – these hardy, long-lived, woody plants thrive in many of Ireland’s milder coastal counties where the chances of harsh spring frosts damaging their emerging flowers are rarer. As a result, old specimens of magnolia can be found growing in many of Ireland’s most celebrated large historic gardens. Examples include Powerscourt, Mount Usher, Kilmacurragh and Killruddery in Co Wicklow, Glenveagh in Donegal, Kylemore in Co Galway, Blarney Castle in Co Cork, Mount Stewart, Rowallane and Hillsborough Castle in Co Down and Mount Congreve in Co Waterford, which is particularly well-known for its magnificent magnolia collection.
Some of the very best grow along Mount Congreve’s famous Magnolia Avenue, home to many different species. One of them is the floriferous Magnolia x soulangeana, or tulip magnolia as it’s commonly known, whose huge, goblet-shaped pink or white flowers appear on bare branches in late March-April. Forming a large shrub/medium-sized tree, it’s happy in full sun or dappled shade and tolerant of alkaline soil.
Until quite recently this species was the most widely cultivated garden magnolia in Ireland and is still often seen flowering in older suburban gardens at this time of year. However, its very spreading growth habit (8m x 8m) – which is only obvious as it matures – means that very harshly pruned specimens are also a common sight. A variable hybrid species, many different cultivars are available. One of the best is the late-flowering M x soulangeana ‘Brozzoni, whose large white-flowers, stained purple at the base, have a better chance of dodging damaging spring frosts.
Also putting on a magnificent display in Mount Congreve’s Magnolia Avenue at this time of year are multiple specimens of two taller, spreading, deciduous species. One of them is the majestic Magnolia campbellii or Campbell’s magnolia, the Cinderella of magnolias on account of its large rose-pink flowers’ particular vulnerability to frost and wind. Planted in the gardens of Mount Congreve in the 1960s, these are now close to 20m in height. In a bad year their plump, downy flower buds can be damaged before they’ve even opened but in a good one, the trees put on a truly magical display. As is true of most magnolias in general, flower colour is affected by light and temperature, typically being more subdued following cool, sun-starved summers.
Another large species of tree magnolia growing along Mount Congreve’s celebrated Magnolia Walk is Magnolia sargentiana var robusta. Just like Magnolia campbellii, this tall, spreading species is known for the natural variability of its giant flowers which appear in March-April and can range from blush to deep rose, as well as their vulnerability to late frosts and cold winds.
Not all magnolias are deciduous and spring-flowering. Examples include the evergreen Magnolia grandiflora, a very tall spreading species (5m x 15m) whose large pale flowers appear in late summer. Thankfully for those with smaller gardens, neither do all magnolias reach such dramatic sizes.
Best known for its suitability for compact spaces is the charming star magnolia, Magnolia stellata, a deciduous shrubby species which not only stays small enough to grow in a large tub (just make sure to keep it regularly watered and mulched) but is also prized for its spidery pale flowers’ relative resilience to frost damage.
Magnolia x loebneri is another excellent choice for smaller gardens. A very variable deciduous hybrid species, it is tolerant of a wide range of soil types including sandy and alkaline kinds while its large starry flowers, which emerge in March-April, are also relatively resilient to frost and wind damage. Outstanding varieties include the magnificent, rose-pink Magnolia ‘Leonard Messel’ (8m x5m); the floriferous, cream, double-flowered Magnolia ‘Mag’s Pirouette’ (5m x 5m), pale-flowering Magnolia ‘Merrill’ (10m x 6m), and ethereal Magnolia ‘Donna’ (6m-8m in height and spread).
Other modern hybrid varieties suitable for smaller gardens include Magnolia ‘Daybreak’ which forms a neatly columnar free-flowering tree (8m x 3m) with giant, pink, deeply perfumed blooms that appear in May, greatly increasing their chance of avoiding frost damage. Magnolia ‘Cleopatra’, whose huge, goblet-shaped purple- pink flowers appear in April-May, is also relatively neat and compact in habit as is the pale-yellow flowering Magnolia ‘Elizabeth’ (5m x 3m), golden-yellow flowering Magnolia ‘Sunsation’ (4m x 3m), bright-pink Magnolia ‘Felix’ and fluorescent-pink Magnolia ‘Watermelon (4m x 3m). Great semi-evergreen options include Magnolia laevifolia ‘Honey Velvet’ which stays compact enough to grow in a large tub. Also worth seeking out is the compact, floriferous, semi-evergreen fairy magnolia. The result of the wondrous skills of New Zealand plant-breeder Mark Jury, its complex parentage is a very closely guarded secret.
This week in the garden
As soils dry out and temperatures start to rise, it’s crucial to get bare-root plants into the ground without delay to give their root systems the very best chance of establishing themselves, making sure to water them well immediately after planting. March is a notoriously busy time of the year for gardeners and it’s very easy to feel overwhelmed. But always try to prioritise the job of seed-sowing as you’ll never make up for lost time in this regard.
Dates for your diary
Sunday, March 23rd (11am-4pm): RHSI Bellefield Gardens, Shinrone, Co Offaly. RHSI Bellefield Plant Fair; A Boutique Gathering for Plant Enthusiasts, with a range of specialist nurseries taking part. rhsi.ie
