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28 May 2021

How to grow magnolias

They’re one of the headline acts of spring, but which of these shrubs should you grow? Discover our Best Buy varieties
Magnolia
CT
Ceri Thomas

As spring gets into full flow, some plants take centre stage and magnolias are certainly one of those. Dating from a time before bees, when beetles were the main pollinators, the extravagant blooms of the deciduous varieties open from furry buds on leafless branches, culminating in a display that never fails to impress. 

Magnolias now come in a wide variety of flower shapes and colours, as well as different tree sizes. They do best in a neutral to acidic soil, but if you have an alkaline soil, you can still enjoy the smaller varieties by growing them in a container filled with ericaceous compost. 

The eventual size of a magnolia can vary, depending partly on location, but it generally takes around 10-20 years to reach maturity– much longer than our usual trial length of two years.

How to grow magnolias: month by month

January February March April May June




FLOWERING FLOWERING



July August September October November December
PRUNE PRUNE PRUNE





Best early-flowering magnolia varieties



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Best Buy early-flowering magnolia varieties
What it looks like Variety name Height x spread
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6 x 6m max
This is one of the larger trees we looked at, and holder of an RHS Award of Garden Merit (AGM). The Savill Garden has a champion specimen that was a magnificent sight in full flower. Tall and stately, the branches arched downwards so the whole outline of the tree was completely festooned with spidery petalled white blooms. The fragrance was one of the strongest of the varieties we assessed, and the flowers were a magnet to bees. Peak flowering: March-April
What it looks like Variety name Height x spread
Member content
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6 x 5m max
This variety can be quite upright in shape when young, but it spreads more as it matures. The tall flowers, often described as candle-shaped, are cool and elegant. They sit upright on short spurs at close intervals along the branches, either singly or in small groups. Deep pink streaks at the base of each bloom liven up the otherwise creamy-white colour of the tepals (petal-like structures that are neither petals nor sepals). Peak flowering: March-April
What it looks like Variety name Height x spread
Member content
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3.5 x 4m max
This variety holds an AGM, and although superficially similar to other species, it’s potentially slightly bigger at full size. It also has larger, fuller and showier flowers with long, soft, white tepals that open from pink buds. It develops into a bushy, rounded, shrub-like tree with pompoms of blooms. The only thing it lacked was scent which, although pleasant, wasn’t very strong. Peak flowering: March-April
What it looks like Variety name Height x spread
Member content
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6 x 5m max
This AGM variety is a potentially tall and upright tree. The mature one we looked at had a domed shape and flower-covered branches that spread and reached down to the ground, while younger trees we saw were bushier and more shrub-like. The flowers smothered the branches, and their long, narrow, pink-blushed tepals curled into a variety of lovely shapes. They were scented and popular with insects. Peak flowering: March-April

How we test magnolias

In March, we visited The Savill Garden and The Valley Gardens in Windsor Great Park, where a National Collection of magnolias is held. We had chosen around 25 varieties of a suitable size for planting in gardens for our assessment, all of which were available from at least one mail-order nursery. 

We noted the impact of the individual blooms and the whole display, which flowers were scented, and which were attracting plenty of pollinating insects. We also noted the size and shape of the trees.

Caring for your plants

Planting

Most deciduous magnolias can be grown in neutral to acidic soil. Plant in a sheltered spot, protected from cold winds and frost. Position in full sun or light shade. Add plenty of organic matter when planting, and mulch well. If growing in a container, use an ericaceous compost and an ericaceous controlled-release feed.

Watering 

Water newly planted trees regularly for the first year while they establish. Water container-grown plants regularly.

Feeding

Mulch annually with 5cm of compost. In spring, you can add a balanced fertiliser, such as Growmore, if soil is poor. Give container-grown plants either liquid feed monthly in spring and summer or add controlled-release fertiliser each spring, with a top dressing of fresh ericaceous compost.

Pruning

Light pruning to remove dead or damaged stems can be done annually if needed. To reduce tree size or renovate a tree, cut small numbers of branches back to a fork evenly around the tree, over several years. Prune mid-summer to early autumn

Common growing problems

Scale insects

Scale insects on leaves can result in sooty mould and poor growth. Look for the round, flat insects around veins on the undersides of leaves, and treat heavy infestations with nematode, Steinernema feltiae

Read more about scale insects

Frost

Frost can damage buds and flowers. Don’t plant in exposed places, and consider protecting small trees with fleece when frost is forecast in spring.

Read more about protecting plants from frost