The sweet gum tree, also known as American red gum, is a beautiful tree with maple-like leaves that turn spectacular shades of purple, crimson, orange and yellow in autumn. It produces small, insignificant green flowers in spring, these may be followed by burr-like fruits. The cone-shaped crown becomes rounded as the tree matures. Older trees have attractive, cork-like bark.
The sweet gum is native to North America, where it’s often found growing in swampy regions. A Spanish naturalist ‘discovered’ the tree in the early 16th century and described its aromatic gum as ‘liquid amber’ – hence its Latin name, Liquidambar styraciflua.
As a sweet gum can eventually reach 25m tall and 8m wide, it’s best grown in a large garden, although more slender and compact varieties are available. Grow as a standalone tree in a lawn so its vibrant autumn colours can be appreciated.
How to grow sweet gum
For the best autumn colour, grow Liquidambar styraciflua in full sun, in rich, damp soil. Sweet gum does not grow well on alkaline soil but does well on acid soil. Grow it in a sheltered spot as wind can snap the branches. It does not need pruning but dead or crossing branches can be removed in winter.
Sweet gum: jump links
- Planting sweet gum
- Caring for sweet gum
- Growing sweet gum: problem-solving
- Buying sweet gum
- Best sweet gum to grow
Where to grow a sweet gum tree
For the best autumn colour, grow a gum tree in full sun, in rich, damp, neutral to acidic soil. Avoid windy spots as wind can snap the branches. As it can eventually reach 25m tall and 8m wide, this is not a tree for a small garden, but you may fit a compact cultivar (see below) into a smaller garden.
How to plant a sweet gum tree
Liquidambar is best planted in winter, when dormant.
- Stand the tree in water to ensure its roots are damp
- Dig a square hole that’s slightly wider than the pot your tree is in, but no deeper. Lightly fork the base and sides of the hole to ensure the soil isn’t compacted
- Remove the pot from container-grown trees and any wrapping from bare-root ones. Tease out and unwind any circling roots. Stand the tree in the planting hole, then lay a cane across the hole to check that the top of the rootball is level with the soil surface
- Backfill around the rootball with the excavated soil, shaking the tree a little to help the soil settle around the roots. Use your heel to firm gently all around the rootball and ensure there is good contact between the roots and the soil
- Stake the tree to prevent windrock, which can tear the roots and create a gap around the base of the trunk that can fill with water and encourage rot. The stake should be about a third of the height of the tree, hammered in at a 45° angle. Attach the trunk to the stake using an adjustable tree tie
- Water the tree thoroughly, then keep it watered during dry spells for at least the first year
Read our detailed guide to planting trees.
Caring for a sweet gum tree
Liquidambar does not need pruning but you could remove dead, diseased or crossing branches while the tree is dormant, from November to March. If your tree is too large, you could try pruning it back by one third – a job best left to a tree surgeon.
Growing a sweet gum tree: problem solving
The sweet gum tree is rarely affected by pests or diseases. It may be affected by honey fungus.
Advice on buying sweet gum
- Check that you have the right spot to grow a sweet gum tree – it needs neutral to acid soil and full sun
- Check that you have enough room to grow a sweet gum – many can grow up to 25m tall, although more slender and compact varieties are available
- Buy from a specialist tree retailer
Where to buy a sweet gum tree online
Best varieties of sweet gum tree to grow
Liquidambar styraciflua ‘Lane Roberts’
Liquidambar styraciflua ‘Lane Roberts’ is one of the most well known sweet gum cultivars available. Its leaves turn a fantastic, rich blackish-red in autumn. This cultivar has the prestigious RHS Award of Garden Merit. Height x Spread: 25m x 8m
- Buy Liquidambar styraciflua ‘Lane Roberts’ from Thompson & Morgan
- Buy Liquidambar styraciflua ‘Lane Roberts’ from Primrose
Liquidambar styraciflua ‘Worplesdon’
Liquidambar styraciflua ‘Worplesdon’ is a selected variety of sweet gum chosen for its particularly good autumn foliage. This cultivar has the prestigious RHS Award of Garden Merit. Height x Spread: 25m x 12m
- Buy Liquidambar styraciflua ‘Worplesdon’ from Crocus
- Buy Liquidambar styraciflua ‘Worplesdon’ from Thompson & Morgan
Liquidambar styraciflua ‘Thea’
Similar to ‘Lane Roberts’ but with a more pyramidal habit. Crimson and purple autumn foliage. H x S: 25m x 12m
- Buy Liquidambar styraciflua ‘Thea’ from Thompson & Morgan
- Buy Liquidambar styraciflua ‘Thea’ from Primrose
Liquidambar styraciflua ‘Slender Silhouette’
As its name suggests, this tree has a narrow profile – while it still reaches a height of 18m it only reaches 2m wide. The foliage turns shades of orange and crimson in autumn. This cultivar has the prestigious RHS Award of Garden Merit. H x S: 18m x 2m
- Buy Liquidambar styraciflua ‘Slender Silhouette’ from Crocus
- Buy Liquidambar styraciflua ‘Slender Silhouette’ from Thompson & Morgan
Liquidambar styraciflua ‘Gum Ball’
A compact form, often grown as a standard, suitable for smaller gardens. Autumn colour in shades of crimson, orange and yellow. H x S: 5m x 2.5m