Gardeners with limited space, have no fear: the Siberian pea tree (Caragana arborescens) is here. Growing to a diminutive height of 20 feet or less, with a spread of about 15 feet, the Siberian pea tree is an adaptable deciduous tree or large shrub that will brighten cramped sites or infertile garden plots with its cheery yellow flowers.
Siberian pea tree has a rounded, upright habit made up of bright green, pinnately compound leaves up to 3 inches long. Leaves turn yellow in the fall, though the Missouri Botanical Garden describes this color change as "insignificant." The primary ornamental feature of the plant is its spring display of inch-long yellow flowers that resemble pea blossoms. Flowers are followed by long yellowish green pods that mature in the summer and explode open to release reddish brown seeds.
Gardeners looking for an even smaller shrub have a selection of Siberian pea tree cultivars to choose from. "Pendula" is a weeping cultivar that grows about 5 feet tall, producing cascading, coarse-leafed branches that extend outwards about 7 feet. "Walkeri" is about the same size, though it boasts lacier, more fern-like leaves and narrower branches than "Pendula." Both cultivars are hardy in U.S. Department of Agriculture plant hardiness zones 3 to 7.
A native of eastern Russia and northern China, Siberian pea tree is exceptionally tolerant of cold weather and may be grown in USDA zones 2 to 7. Washington State University Extension recommends the plant for USDA zone 8 as well. The shrub prefers full sunlight, though it is not at all picky about soil as long as it is well draining. The shrub is drought tolerant once established, though growth can be sped by watering new plants regularly.
Siberian pea tree can be propagated by seed, ideally sown when ripe in a cold frame. Stored seeds will germinate better if soaked for 24 hours in warm water. You may need to scratch the seed and soak it for another 12 hours if it has not become swollen after 24 hours. Germination generally occurs in two to three weeks, according to Plants for a Future. Keep seedlings in a greenhouse for their first winter and plant directly in the garden the following spring or summer, after chance of frost has passed.