Chris Margrave, head gardener at Clumber Park, explains how to grow the best magnolias.
My first memorable encounter with a magnolia was with a beautiful form of magnolia x soulangiana, about 6m/20ft tall, which was totally covered in tulip-shaped, pale pink flowers with a darker base, a truly magnificent tree.
There are many forms of this hybrid, all produce flowers before leaves unfold. Given their ultimate height and width, around 7m/22ft by 5m/15ft, they do need plenty of space to look their best and they can take a few years to flower, so these hybrids may not be the best choice for smaller gardens.
There are now equally free flowering varieties, that will settle down and flower well four or five years after planting, some even with striking red or yellow blooms.
Magnolias grow best in a site sheltered from wind, even better if the site is sheltered from early morning sun, which can damage blossom if it is frosted and thaws quickly. An edge of woodland site with light, dappled shade will suit most varieties best. The ideal soil is moisture retentive during the summer, slightly acid, and doesn’t become water-logged during the winter. Container grown magnolias may be planted now, into soil that has been prepared by being dug over and to which well rotted manure or leaf mould has been added.
A light dressing with a general fertiliser will also help get the plant off to a good start.
No pruning is needed to established magnolias, but some initial pruning to shape young plants by removing or shortening weak, crossing or strong inward growing shoots will produce an attractive, well balanced tree. Pruning is best done in the summer or early autumn, otherwise cuts ‘bleed’ sap, which weakens plants. An annual spring mulch with leaf mould or home-made compost will help retain soil moisture and keep weeds in check.
A bewildering choice of magnolias is offered in the nursery catalogues. Forms of magnolia x soulangiana alone run to over 20 varieties, with flowers in white, creamy whites, pale and deep pinks. Among the newer magnolias, ‘Heaven Scent’ has impressed. In April and May it bears pale pink flowers with deep purple flushes and a magenta stripe. As the name suggests, these are strongly scented. It ultimately grows into a small tree, as does ‘Star Wars’, which produces lots of rich pink goblet-shaped flowers.
An established favourite for smaller gardens is the star magnolia, magnolia stellata. It reaches a height of no more than 3m/10ft and is quite slow growing; its scented, white flowers are produced in March and April. It has a form called ‘Water Lily’, which has bigger flowers with more petals.
Magnolia breeders are working to produce varieties with more frost-resistant flowers, a more compact habit of growth and to extend the colour range to include good reds and yellows. Two new introductions which show promise are the non-fading yellow ‘Yellow Bird’ and the deep red ‘Burgundy Star’.
Spring flowering bulbs make good companions to the early flowering magnolias; grape hyacinths such as Muscari ‘Heavenly Blue’ or Scilla ‘ Spring Beauty‘ can be used to form a lovely blue carpet. Shade lovers such as pulmonarias (lungworts), bergenias and dicentras will also provide good ground cover.
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Most soils should now be warm enough to begin direct sowing hardy annuals. Pot marigolds (calendulas), larkspur and candytuft can be used to produce an attractive flower display – much cheaper than half hardy bedding plants like busy lizzies or French marigolds, which need to be sown and grown on in a greenhouse. Vegetables such as lettuce, early peas, carrots and turnips can also be sown.
Remove faded flowers from early spring flowering bulbs.
If the weather stays dry, new plantings will need watering. A thorough soaking, watering the soil at the base of the plant gets water to where it is needed. Watering early in the morning or in the evening, rather than during the hotter parts of the day, will reduce water loss from the surface of the soil.
Weed seedlings will begin appearing. These are best controlled with a hoe, especially on dry, sunny days.