laburnum
( luh - BURR - num )
At-A-Glance Information
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Known as the Golden Chain Tree or Golden Rain Tree, this showy genus of deciduous trees and shrubs needs full sun (with afternoon shade in the warmest climates of their zone range) and moderate to regular water to perform well. Trees produce chains of dangling yellow flowers in mid- to late spring, and are upright growers, usually pruned into single-trunked trees. They can be maintained as shrubs or espalier subjects on pergolas (as Wisteria is sometimes grown), as well. Take care when planting these trees in your yard, as all parts (especially seed pods) are very poisonous to humans and pets if ingested.
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laburnum Species and Varietals
The genus Laburnum is a member of the plant family Fabaceae and includes two species. Golden Chain Tree grows best in zones 1-10 and 14-17. To find your zone, click here: Zone Map.
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Laburnum alpinum (Scotch Laburnum, Alpine Goldenchain, Scottish Laburnum) This fasst-growing species reaches 30-35 feet tall and 20-25 feet wide. 10-15 inch-long flower clusters bloom in springtime (typically between May and June). Blossoms smell a bit like vanilla. Variety 'Pendulum' has weeping branches. |
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Laburnum anagyroides (Common Goldenchain) This species of Golden Chain Tree reaches 20-30 feet tall and 15-20 feet wide, with 6-10 inch-long flower clusters produced in springtime. Varieties of this species include 'Pendulum' (a weeping selection) and 'Columnaris' (a columnar, upright variety). |
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Laburnum x watereri This hybrid is a cross between Laburnum alpinum and Laburnum anagyroides, and reaches 15-30 feet tall and 10-20 feet wide, with 10- to 20-inch long flower clusters that dangle from branches in springtime. Varieties include 'Sunspire' (also called 'Columnaris', with an upright habit to 20 feet tall and 10 feet wide), and 'Vossii' (a very commonly grown variety that is very graceful-looking and produces 20-inch long flower clusters). |
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Caring for and pruning laburnum Trees
The first step in caring for Golden Chain Tree is to plant it in the correct spot in the garden. These plants prefer to receive at least 6 hours of direct sunlight each day; this will result in optimal foliage and flowering. If trees are grown in partial shade, they may not bloom as prolifically. They are considered understory trees in some locations, however, doing well at the outskirts of tree stands. Plants grown in partial shade tend to be leggier and have a less attractive shape. These trees need to have well-draining soil that is kept moist. They can tolerate a wide range of soil types, however, including loamy and sandy. Substrate should be slightly acidic to neutral, with a pH of between 5.0 and 7.0. If local soils are particularly heavy or clayey, amend planting site with plenty of organic material and/or sand before planting, or consider planting in a raised bed. Apply a thick layer of mulch around the base of new plantings; this will help to increase soil moisture retention, suppress weed growth, and regulate soil temperatures. Water new plantings regularly and deeply. Established plants are considered to be drought-tolerant, and can get by on rainwater alone during the cooler months of the year. During hot, dry weather, deep water trees occasionally.
Apply a feeding yearly in springtime with an organic compost around the base of the tree. These are not heavy feeders, and do not need to be fertilized. If trees seem to be struggling, however, or if they are grown in particularly poor soils, they may benefit from a springtime application of a balanced, slow-release fertilizer before new growth pushes out for the year. Prune these trees after flowering has ended for the year; this is typically in late spring or early summertime. This will avoid cutting off buds for the next season. At this time, remove any dead, damaged, diseased, or crossing branches and open up the canopy to increase airflow. Remove suckers from the base of plants whenever they pop up. Avoid heavy prunings, as flowering for the next year may be affected.
Apply a feeding yearly in springtime with an organic compost around the base of the tree. These are not heavy feeders, and do not need to be fertilized. If trees seem to be struggling, however, or if they are grown in particularly poor soils, they may benefit from a springtime application of a balanced, slow-release fertilizer before new growth pushes out for the year. Prune these trees after flowering has ended for the year; this is typically in late spring or early summertime. This will avoid cutting off buds for the next season. At this time, remove any dead, damaged, diseased, or crossing branches and open up the canopy to increase airflow. Remove suckers from the base of plants whenever they pop up. Avoid heavy prunings, as flowering for the next year may be affected.
Propagation
Laburnum can be propagated either by using cuttings or from seed. To ensure that your propagated plant will have the exact same qualities and characteristics as the parent plant, use the cutting method. If you would like to experiment and see what plant you can grow from seed, just keep in mind that it will not necessarily be the same as the parent plant. To propagate your tree or shrub, follow the instructions below:
Propagating Laburnum by Cutting
Propagating Laburnum by Seed
Propagating Laburnum by Cutting
- Gather your materials. You'll need a clean, sanitized, sharp pair of garden shears, rooting hormone, a pencil, and a 3-inch pot filled with well-draining compost or other organic material. If you don't have any potting medium on hand, you can make some. Just mix together equal parts (by volume) moss peat and horticultural-grade sand or grit sand.
- In fall, choose the plant that you'd like to propagate. Ensure that this plant has had a good watering the night before, as this will improve the chances your cutting will take root. Cut one or more 8-10 inch portion(s) of the end of a non-blooming branch and strip the leaves off of the lower third. Make a hole in your planting medium by pushing your pencil into the soil. Dip the end of the stem in rooting hormone, and plant it in your pot. Fill in soil around the cutting to support it, but do not pack it down too much.
- Moisten with water, and ensure that the pot has good drainage. Your pot should be kept in warm, sunny conditions indoors (and not in direct sunlight). Water whenever your soil is dry under the top layer. After about four to six weeks have passed, your cutting should be rooted. When you notice new growth, you'll know you have roots.
- Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring, when you can transplant it to its new home. Ensure that the last frost of the year has occurred before doing this, as it can seriously damage your new shrub.
Propagating Laburnum by Seed
- Keep in mind that the plant you get from seed will not necessarily mimic all of the characteristics of the parent plant. To propagate by seed, you will need a paper bag, a pot or tray filled with well-draining compost or other organic material, a spray bottle and a fork. If you don't have any potting medium on hand, you can make some. Just mix together equal parts (by volume) moss peat and horticultural-grade sand or grit sand. You will also, after a few weeks, need individual 3-inch pots for each seedling that grows. Take care when working with and storing Laburnum seeds, as they are toxic to pets and humans when ingested.
- Harvest your seeds. The seed pods are pretty easy to spot, they're large and dangle from the branches, left behind after flowers have faded. Once they have dried out and begun to split open, you can harvest the seeds inside. Cut them off of the plant, placing them in a paper bag. Harvest as many as you can, and place the paper bag in a dry, cool, dark area. They will begin to split open and release the seeds contained inside. Once they have been released, take them out of the bag and put them in a container so you can work with them.
- Place seeds in a bowl and pour boiling water over them. Allow them to stay in this water for about 24 hours. Viable seeds will sink to the bottom, and non-viable seeds will float to the top. You can discard any seeds that float. Laburnum seeds have a hard coating that protects them, but this coating also makes it a little difficult to get them to germinate. We can help the process along by scarifying them with sandpaper (or simply rubbing them against an abrasive surface). Do this with as many seeds as you can; they will probably not all sow, and the ones that do will be of varying characteristics (especially if you are working with a hybrid plant). The more seeds you plant, the more chances you will have to get the resulting shrub you want.
- Water your prepared seed tray or pot filled with soil, and ensure that good drainage is occurring. Place your seeds in your prepared pot or seed tray about a quarter inch to a half-inch under the soil surface. Cover them with soil and water with your spray bottle. Place your tray of seeds in a warm area that receives bright, indirect light. A greenhouse is the most ideal climate, but a planting tray inside a window will do as well. Germination usually takes 7-14 days from sowing. Once you begin to see seedlings sprout and they are able to be handled, transplant them to their own individual 3-inch pots, filled with the same potting medium as described in Step 1. Loosen the seedlings from the potting medium by digging down with the tines of your fork about an inch and a half, gently working the seedling up until it is out. Then, replant the seedling in its individual pot.
- Keep the seedling's potting medium moist, but not wet, by spraying the soil with your spray bottle. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring (after the danger of frost has passed), when you can transplant it to its new home.
Laburnum trees produce seed pods that begin green and mature to brown, before drying and splitting open.
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Seeds are small and greenish-brown to black. There are about 8 seeds in each pod.
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Problems and Pests
Laburnum trees, shrubs, and vines are susceptible to the following pests and diseases:
- Aphids
- Mealybugs
- Honey Fungus
- Root Rot
- Sunscald
- Twig Blight
- Laburnum Vein Mosaic
- Spider Mites
- Powdery Mildew
- Caterpillars
Gallery
These garden ornamental trees can be transplanted easily, even when large.
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Laburnum, a member of the Fabaceae plant family, produces pea-form flowers.
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Laburnum can grow as a multi-trunked shrub or small tree, or be pruned to have a single trunk.
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Laburnum can be used similarly to Wisteria, and grows well on trellis and pergola structures.
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Laburnum is a multi-purpose plant, and some gardeners use it as a hedgerow.
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Bees are fantastic pollinators for these brightly colored flowers.
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Videos
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How to identify these plants, even out of flower.
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Learn about the poisonous qualities of these plants.
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Resources
The New Sunset Western Garden Book: The Ultimate Gardening Guide (2012) - Page 395, Laburnum (Golden Chain Tree)
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