A laburnum tree in flower is a beautiful sight – the burst of dripping, golden yellow flowers in May is truly glorious. Laburnum is also known as the bean tree, bean trefoil or golden rain tree, thanks to its hanging, pea-like blooms. The foliage is attractive, too – fine and divided into oval leaflets.
Laburnums can be grown as small, free-standing trees and can also be trained over a pergola, arch or walkway, which show off the pendulous pea-like flower clusters. The most famous example is at Bodnant Garden in Wales. They look spectacular underplanted with purple alliums.
Traditionally laburnums were planted in larger gardens, but there are newer varieties that will suit smaller gardens and containers. Laburnums are deciduous, which means they lose their leaves in autumn, with fresh foliage appearing the following spring. They are fast growers, putting on around 40cm of growth a year.
All parts of the tree, especially the seeds, are toxic to humans and animals if ingested – keep children and pets away from them. Wear gloves and wash hands after handling.
How to grow laburnums
Laburnums are easy to grow, provided they are given a sunny spot and moist, well-drained soil. They are low maintenance trees that only need pruning if they are out of shape, and do not need watering or feeding.
Growing laburnums: jump links
- Planting a laburnum tree
- Caring for a laburnum tree
- Propagating a laburnum tree
- Growing a laburnum tree: problem-solving
- Buying a laburnum tree
- Best laburnums to grow
Where to grow laburnums
In its natural habitat of southern and central Europe, laburnum grows on scrubland and hillsides, so it needs well-drained soil and full sun in the garden. It will grow in partial shade, but it will not produce as many flowers. Waterlogged soils may kill the plant.
How to plant laburnums
As with most trees, plant Laburnum in autumn or winter. Dig a large hole that’s wider than the rootball and around the same depth. Add plenty of well-rotted manure or garden compost to the planting hole. Backfill with garden soil, firm in well and water in. You could then mulch with more manure or garden compost. Stake firmly.
How to care for laburnums
Free standing laburnums don’t need much pruning, other than standard maintenance for size, shape and health – remove any dead, diseased or crossing branches and trim to an attractive shape. However if you’re training your laburnum over an arch or pergola, you will need to trim and tie in the stems. If you have bought a grafted tree, any shoots that grow just below the graft should be removed. Prune between late summer and Christmas – if pruned in spring or early summer the tree is likely to bleed sap.
Watering and feeding
There’s no need to water a laburnum once it’s established, and it does not need feeding.
How to propagate laburnums
Laburnums can be propagated by taking hardwood cuttings in late autumn and winter. You can also sow the seed in autumn.
The caterpillars of laburnum leaf mining moth can cause unsightly circular blotches on the leaves. It rarely affects the health of the tree and does not need treating – you may find that natural predators (such as blue tits) keep it under control.
Sometimes laburnums produce very heavy blooms one year, and then a less abundant display the next. This is entirely normal and nothing to worry about.
Great laburnum varieties to try
- Laburnum x watereri ‘Vossii’ – the best known variety, a cross between the two species laburnums, Laburnum anagyroides and Laburnum alpinium. It’s a fast-growing tree with dark green leaves, and very long, scented flower racemes. It will flower even when young. It has been given the prestigious RHS Award of Garden Merit (AGM).
Height x Spread: 8m x 8m
- Laburnum anagyroides ‘Yellow Rocket’ – a new introduction with a narrow, upright habit which makes it ideal for smaller gardens.
H x S: 2m x 4m
- Laburnum x watereri ‘Sunspire’ – a new variety, with medium height and a narrow habit, that would suit smaller gardens.
H x S: 4m x 2m
- Laburnum alpinum ‘Pendulum’ – this is a weeping Scotch laburnum. A smaller tree, it looks great as a stand-alone feature tree, and is a good choice for smaller gardens and containers.
H x S: 2m x 2m