Laburnum alpinum (Mill.) Bercht. & J.Presl
Scotch Laburnum, Scottish Laburnum, Alpine Laburnum, Alpine Golden Chain Tree, Alpine Bea Tree
Cytisus alpinus (basionym), Genista alpina
Bloom Time: May to June
Laburnum alpinum is a deciduous tree similar to Laburnum anagyroides. It grows up to 16 feet (4.9 m) tall and up to 20 feet (6 m) wide at a fast rate. The leaves are odd-fingered with three oblong, single leaves. The leaf margin is smooth and the petiole longer than the leaf. The leaf arrangement is alternate. It is in flower from May to June, and the seeds ripen from September to October. The panicles of yellow, vanilla-scented, pea-like flowers are hermaphrodite (having both male and female organs). The fruit is a pod or legume, the seeds green at first but becoming shiny black.
How to Grow and Care
Choose a growing site that is exposed to full sunlight. The more sunlight, the better the Laburnum will bloom. An exception to this rule is home gardeners who live in USDA zone 8. Laburnums do not tolerate heat well, so gardeners who live in hotter climates should choose a location that gets morning sun but is shaded from direct exposure to hot afternoon sunlight.
Plant your Laburnum in fertile, well-drained soil. These trees are small — they average about 20 feet (50 cm) in height — so they can also be grown in containers. If you use a container, make sure it has drainage holes.
Water frequently. These trees thrive in cool, moist soils and grow best in climates that have mild, wet summers. Water at least once each week — more often when the weather is hotter than usual.
Fertilize in early spring before bud break. Use a fertilizer formulated for flowering trees and shrubs, and one that has a high acid content. Laburnum thrives in high pH soils. Follow the directions on the package according to the size and age of your Laburnum. See more at How to Grow and Care for Laburnum.
Native to Central and Southern Europe.