Liquidambar styraciflua, or sweet gum, is native to eastern USA where it can grow to enormous proportions. Liquidambar styraciflua 'Lane Roberts' AGM is much smaller and was named after a gynaecologist who, during his career, delivered two babies destined to become presidents of the RHS. Here at RHS Garden Rosemoor, the tree can be relied upon to produce a brilliant display of deep crimson autumn colour and is considered one of the best Liquidambars available.
With a height of 7-12m (23-39ft) and a compact form, it will easily slot into a medium sized garden. Acid soil and a sunny site will produce the best autumn colour while glossy green, deeply lobed leaves also make it a lovely tree for spring and summer.
Interestingly, our specimen in the stream garden field colours considerably later than the one in the terrace garden (one of the model gardens), probably because it receives less sun. However, this means that the glorious colours last from mid-October into December.
The specimen in the stream field garden is backed by a variety of trees and shrubs in the main border, many of which also produce sensational autumn colours including: Cornus, Euonymus and Prunus. The tree in the terrace garden forms a vibrant focal point on the path from the visitor centre, contributing to the wider autumn display in this part of the garden.
How to plan your planting
When choosing under-planting, consider how the foliage and flowers will combine with the colourful fallen leaves of the Liquidambar. In the terrace garden, the glossy green leaves and the reddish-purple flowers of Vinca minor 'Atropurpurea' AGM and the green leaves of Bergenia cordifolia 'Purpurea' compliment the dark red leaves of the Liquidambar. We have also used berberis as a shrubby layer, mixing purple Berberis thunbergii f. atropurpurea 'Helmond Pillar' with bright yellow Berberis thunbergii 'Golden Torch'.
Liquidambar styraciflua 'Lane Roberts' AGM does not fail to please at Rosemoor, and given the right conditions, it will thrive and light up any garden especially when the deep red leaves glow in the low autumn sun.