Magnolias

The species and varieties of magnolias that make big trees are unrivalled for the ornamental impact that they can produce. Even the smaller ones are as showy as any cherry or crab-apple, with the display lasting much longer.

Nowhere in the British Isles is the climate more to their liking than in Cornwall and it is here that many of the finest collections may be found, providing truly breathtaking displays in years when the weather is kind and frosts don't wreak too much havoc.

Choosing your plant.

It takes a great deal of space to build a collection of magnolias; most are medium to large sized trees at maturity. Given enough space just about every species and variety of magnolia hardy in our climate is worthy of a place in the garden. It is when space is limited and there are many competing demands on it that making a choice is most difficult.

Magnolia stellata, its varieties and its hybrids are the place to look for plants that will make large shrubs or small trees suitable for smaller gardens. The species itself is probably the most compact and is a free flowering shrub with white flowers having 10-14 tepals. (There is no distinction between sepals and petals in magnolias, the word tepal was coined by G. H. Johnstone from Trewithen to avoid confusion)

Many pink flowered forms of M. stellata exist but in most years in Britain have no more than a hint of pink to them, requiring more heat to colour to their full potential.

Given enough space just about every species and variety of magnolia hardy in our climate is worthy of a place in the garden

Magnolia x loebneri is a group of hybrids between M. stellata and M. kobus and M. x loebneri ‘Leonard Messel’, which is one of the most widely available forms of the cross, produces pink stellata type flowers reliably every year, on a bushy tree to about 15 feet. 'Merril' is another of the same cross and produces a great abundance of pure white scented flowers with rather broader petals on a somewhat bigger tree.

The other important and useful group of stellata hybrids is the set of crosses with M. lilliflora made at the US National Arboretum by Francis de Vos and William Kosar and known as the "eight little girls". These include Susan, Jane, Ann and others, producing pinky-purple flowers very freely and over a long period on a bush or small tree up to about 15 feet.

New varieties are still appearing from America, particularly yellow flowered forms.

When it comes to the mid-range, size wise, there is a complete surfeit of riches. Magnolia x soulangeana was the first hybrid to be made in cultivation, combining M. denudata and M. liliflora to produce a range of forms most of which have white tepals with a purple flush at the base. Given the right conditions they can make large trees but are usually seen in gardens as wide spreading large bushes with a short trunk and a crown at least as wide as it is high. They are easy to grow, free flowering and late enough to avoid spring frosts most years.

Todd Gresham in the USA raised many crosses between the large tree M. x veitchii and either M. x soulangeana 'Lennei Alba' or M. lilliflora. ‘Heaven Scent', 'Manchu Fan' and 'Raspberry Ice' are from this stable along with many others. In this country they don't develop the richness of colour that is seen in the USA but they are very good performers, flowering freely and for a long time, as much as 8-10 weeks in a good year.

More recently New Zealand has become the focus of breeding efforts. Mark Jury kicked it off by producing some superb varieties like 'Iolanthe', 'Athene', 'Milky Way', 'Vulcan' and others. 'Star Wars' was raised by Os Blumhardt and more recently still the names to watch have been Ian Baldick and Vance Hooper.

New varieties are still appearing from America, particularly yellow flowered forms.

In Cornish gardens the greatest impact comes from the large growing Asiatic species, particularly campbellii and sprengeri and their various forms and hybrids. The greatest drawback with these forms is how long it takes young plants to flower; for seedlings it may be over 20 years.

Cultivation.

Shelter from wind is important in places like coastal Cornwall.

Magnolias are essentially woodland plants and want adequate moisture, plenty of organic matter and minimal root disturbance. They generally prefer acid soils though this is probably less important than being moist and humus rich and a number of species are quite tolerant of alkaline soils, notably M. grandiflora, x loebneri and x soulangeana.

In Britain most will be happy in full sun, where they will flower more freely, though a mulch should be applied to protect the roots. In the relatively hot and dry parts of the country, shade will be of benefit, especially for the wilsonii/sieboldii/globosa types.

Shelter from wind is important in places like coastal Cornwall and frost hollows should be avoided or damage to flowers and emerging shoots may be severe.

In general neither feeding nor pruning will be required. If the soil is nutrient poor then a high nitrate feed in spring will be of benefit. Light formative pruning is best done around August for spring flowering types. More drastic pruning, of deciduous or evergreen varieties, should be carried out in late winter before growth begins.