Whether large trees or small bushes, magnolias like cool roots, good drainage, and at least half a day full sun. When planting, add as much compost as you can and mulch to conserve soil moisture. If the site is prone to waterlogging, raise the planting area and mulch heavily to encourage root development above the waterlogged soil.
As a container subject, the same cool root system can be achieved by shading the container from direct sun. Regular water and fertiliser will reward you with a spring display and the bonus of summer flowers on most of the modern hybrids.
If trimming is required, a selective trim to thin the longer branches will maintain shape without forcing vigorous regrowth.
Traditionally, the small-growing magnolias were Magnolia stellata and M. liliiflora types. These were hybridised to produce “The Little Girls”, namely ‘Susan’, ‘Betty’, ‘Ricki’ and others. Several slender upright varieties have been introduced in recent years. These, too, work well in small gardens.
While the “Kiwi quarter acre” was the norm, most breeders ignored or even destroyed the smaller seedlings as runts but smaller gardens mean the smaller varieties are more attractive.
Top small varieties
The following magnolias are from several breeders and are the best smaller varieties available today:
‘Amethyst Flame’ is a free-flowering vibrant purple. A compact bush to 2.5m x 1.5m in 10 years.
‘Burgundy Star’ is a slender tree with many burgundy red blooms on an upright tree to 4m x 1.5m in 10 years.
‘Genie’ is a popular Magnolia Grove hybrid. Masses of rich red flowers on a columnar small tree, 4m high x 1.5m wide in 10 years.
‘Lennei Alba’ is the smallest growing white M. soulangeana hybrid with white goblet-shaped blooms. This variety will grow it about 2.5m x 2.5m in 10 years.
‘Mighty Mouse’ is a true dwarf variety from Magnolia Grove. With miniature flowers and leaves to scale, it is suitable for a bonsai subject. It is also produced on a short grafted standard like a standard miniature rose, ideal for under-planting with miniature hostas. This will grow to 1m x 1m in 10 years.
‘Royal Purple’ has rich purple blooms and an upright columnar habit to 3.5m x 1.5m in 10 years.
Magnolia stellata is now available in a wider range:
‘Centennial’ is a selection from M. stellata
‘Waterlily’ and has white flowers blushed pink in cool weather. It is the most fragrant of the stellatas, growing to 2m x 2m in 10 years.
‘Dawn’ is the strongest growing of the rich pink stellatas and will get to 2.5m x 2m in 10 years.
‘Jane Platt’ is an excellent pink with very frilly flowers. More compact than ‘Dawn’, reaching 2m x 1.5m in 10 years, and is also available as a grafted standard.
‘Sun Spire’ is a slender, upright, yellow hybrid with rich yellow blooms on bare branches. It grows to 4m x 1.5m in 10 years.