Whoever gave this shrub its common name – bladder senna – didn’t do it any favors. What is a bladder senna? Bladder senna bush (Colutea arborescens) is actually an attractive plant with spring flowers. Its puffy seed pods, which are in the shape of bladders, mature in autumn. Read on for more bladder senna information.
I. Appearance and Characteristics
Colutea arborescens is a species of leguminous shrub known by the common name bladder-senna. It is native to Europe and North Africa, but it is known on other continents where it is grown as an ornamental and used in landscaping for erosion control. It is also known in the wild as an occasionally weedy escapee from cultivation.
It is a vigorous shrub to 3 m, takes a rounded form and has many branches covered in deciduous leaves. The leaves are pale green and made up of many pairs of slightly hairy oval-shaped leaflets, each up to about 3 cm long. The inflorescence is a raceme of generally pea-like yellow flowers about 3 cm long. The fruit is an inflated bladdery pod which dries to a papery texture. It is 2 to 3 cm long and contains many seeds.
Bladder senna bushes are pioneer plants that grow readily in disturbed areas. They attract wildlife and provide pollen for insects. The shrubs are hermaphrodite, which means that each one has both male and female organs.
It will grow in poor dry soil in exposed conditions, but likes full sun. It propagates by seed or softwood cuttings.
II. How to Grow and Care
Bladder-senna is a hardy and adaptable shrub that generally requires minimal maintenance, making it an easy plant to care for. Key points in its care include ensuring well-drained soil, as it does not tolerate waterlogged conditions, and providing full sun to partial shade for optimal growth. Pruning is beneficial after flowering to maintain its shape and promote new growth.
Sunlight
Bladder senna (Colutea media) is a plant species that does best in full sunlight. For optimal growth, it should receive at least 6 hours of direct sunlight per day. The plant is drought tolerant and can survive on the sunnier side of a building, on a shelf or higher off the ground on a wall. The plant should be moved to a location with more light during the winter months when the sun angle is lower and the days are shorter. Even with low light levels, bladder senna can still survive, although the leaves will be smaller and the plant will be less vigorous.
Watering
Originating from the rocky hillsides of Europe, bladder-senna is adapted to a somewhat arid environment, thriving in conditions where moisture is not abundant. This species exhibits moderate drought tolerance and prefers a dry down between waterings to prevent root rot. As such, it should be watered once every two weeks. In its native habitat, bladder-senna has evolved to efficiently use the sporadic rainfall typical of its Mediterranean climate. Being an outdoor plant that can handle various temperature ranges, bladder-senna often experiences growth spurts during rainy seasons while requiring less hydration during cooler, dormant periods.
Soil
Bladder senna shrubs are not picky about soil types. They can grow in a variety of situations, accepting clay, loan, silt, sand and shallow rocky soil. They are not particular about soil pH either, and grow in acidic, alkaline and neutral soil.
Fertilizing
For bladder-senna, apply balanced nutrition fertilizers annually in early spring, with a focus on potassium to enhance flowering. Use a modest amount per instructions to prevent overfertilization, which can harm the plant. Seasonal variations are minimal, but younger plants may benefit from more frequent feedings. Always water bladder-senna thoroughly post-fertilization for optimal nutrient absorption. Regular feeding of bladder-senna increases growth robustness and boosts flower production, improving overall plant health. For gardeners, using gloves during fertilization is advised to protect skin.
Pruning
Bladder senna (Colutea media) should be pruned during the winter months (December-March). The best time to prune is just before new growth is expected, usually in late winter. Pruning should be moderate to maintain the desired size and shape of the plant. The branches should be pruned back to 2 to 3 buds from the main stem. When trimming shrubs, larger branches should be pruned into smaller ones, creating a more bushy appearance. Avoid cutting back more than 1 third of the branches for any single pruning session.
Propagation
Bladder-senna is a resilient shrub noteworthy for its distinctive inflated seed pods. To propagate, seeds should be directly sown into a well-draining soil mix after undergoing a period of stratification. This cold treatment stimulates germination, a critical step given bladder-senna’s dormancy characteristics. Once sown, maintain consistent moisture and warmth to encourage sprouting. As seedlings establish, ensure adequate sunlight and minimize transplant shock by careful handling of the delicate roots.
Transplanting
The vernal season breathes life into gardens, making it a prime time for settling bladder-senna into its new locale. Ensure a sunny spot with well-drained soil—a welcoming foundation for its roots. Keep transplant stress minimal with gentle handling and soil familiarization.
III. Uses and Benefits
One reason gardens like to plant bladder senna is that they can fix nitrogen in the soil.
Some people use this shrub medicinally. The bladder senna leaves are said to be mildly diuretic and can be used instead of senna as a laxative. However, the effects are not reliable, making it difficult to count on this plant as a medicinal herb.
