Evergreen magnolia trees really are a sight to behold, especially when in bloom with their fragrant cream flowers. Read on to find out more about the Magnolia grandiflora and discover the best varieties for your garden.
Although native to warmer climates, Magnolia grandiflora, or Bull Bay or evergreen magnolia as it is also known, can also be grown here. Keep reading to find out how to care for evergreen magnolias and discover the finest variety for your garden.
Evergreen magnolia: origin and characteristics
Magnolia grandiflora trees are members of the Magnoliaceae family that originate from the southeastern United States, lending them their nickname of the Southern Magnolia. In their natural environment, evergreen magnolias can mature into large trees up to 20m in height. However, here in the United Kingdom, a maximum height of around 10m is more realistic for this slow-growing shrub or tree.
Evergreen in nature, Magnolia grandiflora produces impressive foliage. Its glossy dark green leaves with a fuzzy brown underside are oval and pointed and can grow up to 20cm long. Generally single-stemmed with a pyramid-to-round shape, the slow to establish evergreen magnolia develops a shallow root system and grey bark as it matures.
However, May to September is when the evergreen magnolia produces its dazzling display of cream flowers for which it is prized. Depending on the variety, the fragrant cup-shaped Magnolia grandiflora flowers can grow to 25cm in diameter and contrast strongly against the deep green foliage. As the flowers fade, they leave behind pink-red cone-shaped fruits.
Tip: evergreen magnolias can take up to 25 years to produce their first flowers. However, those grown on a grafted rootstock can flower in as little as 5 years.
The most beautiful varieties of evergreen magnolia
Along with the wide range of other magnolia varieties available, evergreen magnolia varieties can vary in size and habit. There are also some hardier cultivars, which are most suitable for colder areas or those prone to harsh winters. Here are some of the best evergreen magnolia varieties for your garden:
- Magnolia grandiflora ‘Alta’: tall columnar habit up to 6m tall and 2m wide; very hardy down to -15 °C; white flowers up to 20cm across.
- Magnolia grandiflora ‘Galissonière’: large variety which can grow to 10m high and wide when mature; large cream flowers; hardy to -15 °C.
- Magnolia grandiflora ‘Goliath’: round and bushy habit with a long flowering period; eventual size of 12m high by 12m wide; hardy to -10 °C.
- Magnolia grandiflora ‘Kay Parris’: compact form to a maximum 6m tall by 2 to 3m wide; large scented white flowers; hardy to -15 °C.
- Magnolia grandiflora ‘Little Gem’: dwarf variety that is suitable for growing in a container; columnar habit up to an eventual 8m tall by 3m wide; hardy down to -10°C.
- Magnolia grandiflora ‘Mainstreet’: conical shape to an eventual height of 12m and 8m wide; large fragrant white flowers; hardy to -10 °C.
- Magnolia grandiflora ‘Victoria’: large rounded habit with a maximum size of 12m high by 8m wide; hardy to -15 °C.
Planting evergreen magnolias
Magnolia grandiflora trees thrive in sunny and sheltered locations. They can tolerate some slight shade, but for the thickest growth, full sun is best. Evergreen magnolias can cope with most soil types. However, they prefer a well-drained, slightly acidic soil that is kept moist, but not waterlogged. They require frequent and deep irrigation until they have established as well as during hot and dry spells.
Being generally hardy down to -10 °C, Magnolia grandiflora can tolerate outdoor positions as long as it is sheltered from any harsh winter winds. In frost pockets and colder areas, you can grow Magnolia grandiflora in pots and overwinter them undercover. When planting an evergreen magnolia in a pot, choose one that is one to two sizes larger than the current root ball with adequate drainage holes. Fill the pot with a slightly ericaceous compost and plant it at the same depth it was previously planted. Our Plantura Organic Ericaceous Compost is ideal for growing evergreen magnolias as it is slightly acidic and, being low in peat, is an environmentally-friendly option. Once planted, water regularly to keep the soil moist and mulch annually in the autumn or spring.
Planting Magnolia grandiflora summary:
- Choose a sunny or semi-shaded and sheltered location
- Plant using a fertile, slightly acidic, well-drained soil
- Water regularly until established
- Mulch annually with organic matter
- Provide frost protection or move container-grown specimens under cover in the winter
- Perfect for acid-loving plants such as hydrangeas, rhododendrons, blueberry bushes, azaleas & more
- Ensures all-round healthy plants with lush blooms and aromatic berries
- Peat-reduced & organic soil: CO2-saving composition
Magnolia grandiflora care
When given the correct growing conditions, evergreen magnolia trees generally grow well. However, ample moisture and nutrients are essential for helping Magnolia grandiflora trees establish, especially when grown in containers.
Pruning Magnolia grandiflora
Depending on the cultivar, Magnolia grandifloras tend to naturally produce a pyramidal or rounded shape. Pruning Magnolia grandiflora is not strictly necessary unless you’re growing it as a wall-trained specimen, which you can prune in summer. However, you can prune standard shrubs and trees in spring as new growth appears, which is generally in March or April. When pruning a Magnolia grandiflora, remove any dead or diseased wood back to a healthy branch using a clean and sharp pair of secateurs or loppers. If you desire, you can also remove the lowest limbs to expose the lower trunk and prune to shape and size.
Fertilising and watering Magnolia grandiflora
To help your Magnolia grandiflora establish and thrive, water regularly for the first few years after planting and during droughts. If growing an evergreen magnolia in a container or against a wall, more frequent irrigation will be necessary to prevent the soil from drying out.
When it comes to fertilising Magnolias, younger plants and those grown in a pot will benefit from extra nutrients. You can feed evergreen magnolias planted in the ground with a balanced general fertiliser every spring for the first few years. As pot-grown specimens have less access to nutrients, apply an ericaceous feed throughout the growing season. Our Plantura Hydrangea Food is perfect for this as it will help support the plant’s growth and, being a slow release fertiliser, will feed the plant for up to 3 months.
- For beautiful hydrangeas with lush blooms in pots & flower beds
- Prevents common deficiency symptoms & supports healthy plant growth
- Long-lasting fertiliser that is free from animal products - child & pet friendly
Are evergreen magnolias winter hardy?
In our climate, evergreen magnolia trees are generally winter hardy and can survive a typical frost and temperatures around 0 °C to -5°C. However, if low temperatures are forecast, it is best to protect smaller or less hardy shrubs and trees with a layer of fleece. For container-grown magnolias, you can either move them under cover or add a layer of fleece over the crown and insulate the pots with bubble wrap. If you live in a frost pocket, it is advisable to either grow one of the hardier cultivars or grow them in pots so that you can move them to an unheated greenhouse as temperatures drop.
Is Magnolia grandiflora poisonous?
Strictly speaking, evergreen magnolias are not poisonous to humans, but nor are they intended for consumption. Consuming the bark, wood or fruit of these plants could cause symptoms of mild poisoning or irritate the mucous membranes. It is advisable to wear gloves when handling evergreen magnolias, as they can cause skin and eye irritation. Whilst they are also not considered toxic to animals, smaller pets may experience gastrointestinal issues if consumed.