There are only two species in the genus Laburnum, common laburnum (Laburnum anagyroides), and alpine laburnum (Laburnuym alpinum), both native to southern Europe. What is commonly referred to as golden chain tree in the United States is Laburnum x watereri, a cross between the two species that is considered a superior tree for landscaping than either parent.
This stunning beauty has golden-yellow flowers with which it drips in late spring. The racemes have a strong fragrance. The golden blooms may be 10 to 20 inches in length. On older specimens, the bark is often dark and quite fissured. Leaves are made of three leaflets that look like pointy clover leaves.
Golden chain trees should be planted in the fall or early spring. They grow at a moderate pace.
All parts of the tree contain cytisine and are highly toxic to humans, and toxic to pets.
|Common Name||Golden chain tree, bean tree, Waterer laburnum|
|Botanical Name||Laburnum x watereri|
|Mature Size||15-25 ft. tall, 9-12 ft. wide|
|Soil Type||Well-drained, moist|
|Soil pH||Acidic, neutral, alkaline|
|Hardiness Zones||5-7 (USDA)|
|Toxicity||Toxic to humans, toxic to pets|
Golden Chain Tree Care
Laburnum is the goldilocks of the plant world, and not just in appearance. It grows best in a narrow range of USDA planting zones (5 through 7). Just like in the fairy tale, it does not like it too cold, but it does not like it too hot, either, especially if you are keen on an optimal floral display.
Golden chain tree is relatively rare due to its fussiness about its growing conditions. Still, its beauty makes it well worth trying if you have a climate conducive to growing it.
Young specimens require staking, as the trunks are quite floppy.
If you live in a more moderate climate, pick a spot with full sun to plant your golden chain tree. In warmer climates, choose a climate with partial shade since your tree will get too hot in full sun.
Golden chain tree grows well in most soil types. Good drainage is crucial but in terms of soil acidity, the tree adapts to a variety of pHs, from slightly alkaline to slightly acidic. Ideally the soil has a high contents of organic matter.
The tree has medium moisture requirements, and it is fairly drought tolerant. Be sure the water doesn't puddle at the base since it doesn't do well in standing water and is particularly susceptible to root rot.
Apply fertilizer in early spring (one designed for flowering trees and shrubs, with a high acid content). For the amount to use, follow the product label instructions.
Temperature and Humidity
Golden chain trees prefer moderate climates, not too hot or too cold. Even though they can grow in hardiness zone 7, young trees may not survive the climate's heat.
Golden Chain Tree Varieties
There are three notable cultivars of the golden chain tree:
- Laburnum anagyroides 'Sunspire', a dwarf variety growing 12 ft. tall and 6 ft. wide
- Laburnum anagyroides 'Yellow Rocket', a trademarked cultivar with a columnar, narrow growth habit that makes it suitable for smaller spaces
- Laburnum × watereri 'Vossii', a cultivar that produces fewer pods and less seeds than other types
Pruning is required to develop a strong structure. It should be pruned to grow with a single leader. You can also prune the lower branches since they will droop down and get in the way.
The seed pods can be removed as they appear; they aren't particularly attractive and take energy away from the rest of the tree.
Propagating Golden Chain Tree
Unless it is the trademarked cultivar 'Yellow Rocket' you can propagate the golden chain tree from root cuttings, hardwood cuttings, or whip-grafting. Propagation from hardwood cuttings is the easiest for home gardeners. Here is how it's done:
- In the fall, choose a strong stem and cut 8 to 10 inches off it with a sharp knife, making sure to include at least a few nodes.
- Remove leaves from the lower third. Dip the stem in rooting hormone. Plant the cutting in a 4-inch pot filled with damp potting mix.
- Overwinter the cutting in a protected location outdoors such as a cold frame. Keep the soil moist at all times.
- In the spring, if the cutting has rooted, new shoots will appear. Leave plants in the pot for at least another year until you have a strong sapling.
Growing From Seed
All the commonly grown golden chain trees are cultivars or cross-breds. Starting them from seed won't produce a tree true to the parent and is therefore not recommended.
Potting and Repotting Golden Chain Tree
The smaller varieties of golden chain tree can be grown in containers. The container needs to be heavy enough so it does not topple over. For adequate drainage, it should have large drain holes.
Once the tree outgrows its container, repot it in a container one size up from the original pot.
Laburnums are susceptible to sunscald, which happens when nighttime temperatures drop after warm days. The cold damages trees with a thin bark. To protect it, wrap the trunk with with tree wrap before the onset of winter.
Common Pests and Plant Diseases
Because of its (toxic) seeds, golden chain tree is also considered messy.
Where do golden chain trees grow?
The tree is native to Europe but one of the few locations in the United States where golden chain tree grows abundantly is Bar Harbor, Maine. This is no coincidence, since Bar Harbor, which sticks out into the North Atlantic, is an area known for its cool summers. A famous landscape architect, Beatrix Farrand (1872 to 1959), understood that the climate in Bar Harbor would be perfect for golden chain trees. The word from the locals is that it was Farrand who introduced laburnum × watereri to those parts. Many residences and businesses still sport golden chain trees as specimen plants. These beauties are also commonly seen growing wild along a few stretches of road in the area.
Is laburnum a wisteria?
How old can a laburnum get?
It is not a very long-lived tree; the average life span is 25 to 40 years.