Baguenaudier - Colutea: planting, pruning, and caring for

Botany and description

The Colutea, also known as bladder senna or bladder tree, is a genus of plants belonging to the Fabaceae family. Its name comes from the ancient Greek “kolutea”, which evokes the idea of hollow wood, referring to its fruits: small, swollen, translucent pods that, when dried, resemble small bladders. This genus comprises about 25 species, among which Colutea arborescens, or common bladder senna, is the most widespread due to its hardiness and characteristic fruits. Colutea orientalis is also appreciated, particularly for its colourful flowering and more compact form.

Colutea arborescens: botanical plate circa 1790

These bushes are particularly well adapted to dry, sunny environments. They are naturally found in Mediterranean regions, from southern Europe to the Middle East and Central Asia. They thrive in calcareous, poor, well-drained soils and are quite drought-resistant, making them perfect candidates for dry gardens.

Did you know? The name “bladder senna” comes from the old French verb baguenauder, which means “to amuse oneself with trifles” or “to wander aimlessly”. This term was given to Colutea because of its fruits shaped like small, swollen bladders, light and fun to pop between fingers, like a child’s game. Indeed, the light, translucent pods, which almost float in the air, are perceived as a symbol of lightness, evoking simplicity and carefreeness.

The bladder senna is a bush that stands out for its bushy and airy appearance, reaching heights of between 2 and 3 metres. Its habit is naturally spreading, with flexible, arching branches that give it an elegant yet somewhat untidy silhouette. This form makes it a beautiful shrub for natural gardens or those with a Mediterranean style.

Its root system is taprooted and powerful. The plant can thus anchor well in poor, stony soils and withstand periods of drought. It is a hardy plant, capable of tapping into water deep in the ground, making it a good candidate for dry gardens and arid terrains.

The foliage of Colutea is deciduous, composed of pinnate leaves of a lovely soft green. Each leaf consists of small, oval, rounded leaflets, slightly velvety to the touch. This light foliage creates an impression of softness and complements its flexible habit well.

The inflorescence of Colutea consists of clusters of papilionaceous flowers, typical of the Fabaceae family. The flowers are generally yellow, sometimes tinged with orange or red depending on the varieties. They appear throughout the summer and attract pollinating insects, such as bees and butterflies, thus contributing to local biodiversity.

A graceful flowering and light foliage, with very original coppery fruits

Finally, the fruiting is one of the most striking characteristics of Colutea. After flowering, the shrub produces swollen pods, shaped like small, translucent, hollow bladders, which take on a reddish hue as they ripen. These fruits, filled with air, are light and often popped by children. They remain on the plant in autumn, adding a decorative touch even after the leaves have fallen. These bladder-shaped pods, which ripen in late summer, also provide temporary shelter for certain insects, creating small “hiding places” where they can protect themselves from the elements or predators.

The bushy growth and flexible habit of the bladder senna make it perfect for creating free hedges, where it can blend in without the need for strict pruning. It also finds its place in naturalistic beds, where its light foliage and yellow summer flowers brighten up the plantings. The bladder senna integrates particularly well into the borders of dry gardens, alongside other drought-resistant plants. At the edge, it acts as a beautiful, resilient, and elegant green screen, harmonising with the Mediterranean or wild style thanks to its hardiness and ease of maintenance.

The most beautiful varieties

Colutea arborescens

Colutea arborescens is native to southern Europe and North Africa. Robust and easy to grow even in poor, stony soil, the bush is not spectacular, but it offers original, decorative fruiting throughout summer.

• Période de floraison June to August
• Hauteur à maturité 2 m

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Colutea media Copper Beauty

Colutea (x) media Copper Beauty is a hybrid variety of bush with beautiful copper-orange flowering, more decorative than that of the bush found in our southern countryside known as the bladder tree.

• Période de floraison June to October
• Hauteur à maturité 1,75 m

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Planting the Judas tree

Where to plant?

To plant a baguenadier, choose a sunny location and well-drained soil, preferably calcareous or stony, as it does not tolerate standing water. This bush is ideal for dry or rocky gardens, and it tolerates poor soils and drought conditions once well established.

Colutea does not cope well with heavy, poorly drained soils, which retain water and increase the risk of root rot, a common issue for plants suited to dry environments. If your soil is clayey, it is advisable to improve drainage before planting the baguenadier by adding compost, gravel at planting, and/or planting on a mound.

Colutea arborescens planted here in a wild hedge (©De Tuin-Flickr)

When to plant?

The ideal time to plant is in autumn, between October and November, as this allows the roots time to establish before spring. In regions with harsh winters, you can also plant in early spring, but be sure to water it regularly during the first few weeks to help its roots settle in.

How to plant?

• Dig a hole: prepare a hole about twice as wide as the root ball of the plant.
• Gently place the root ball of the plant in the hole, positioning it so that it is upright.
• Fill the space around the root ball with the original soil, lightly compacting as you go to keep the plant in place and avoid air pockets.
• Water generously immediately after planting to encourage rooting, even if the soil is dry or well-drained. This initial water supply helps the plant get off to a good start.
• Once well established, the baguenadier requires little maintenance. A light pruning each year will suffice, ideally at the end of winter, to encourage a more harmonious habit and stimulate a beautiful flowering the following spring.

Maintenance, pruning and watering

Pruning

• When to prune?: Pruning should ideally be done at the end of winter, before the new growth starts, usually in February or March.
• How to prune?: Carry out light pruning to maintain a harmonious habit and encourage flowering. Remove dead, damaged, or overly old branches, and shorten any shoots that disrupt the shape of the bush. If necessary, you can also cut back more severely every 2-3 years to rejuvenate the bush, cutting back to 20-30 cm from the ground; it will regrow vigorously.

Watering

During the first year after planting, water regularly to help the roots establish, especially during prolonged dry spells. However, once well-rooted, Colutea tolerates drought very well and requires virtually no watering, except during extended heatwaves.

You can add a mineral or organic mulch around the base to limit weed growth and retain some moisture, especially in the first year.

Fertilisation

In principle, no fertiliser is necessary. Colutea thrives in poor soils, and too many nutrients could encourage leaf growth at the expense of flowers.

Colutea arborescens

Diseases and Pests

Colutea is a particularly hardy and resilient plant, and it is rarely affected by diseases or pests.

However, under inadequate growing conditions, such as poorly drained soil or excess moisture, it can be vulnerable to root rot, a fungal disease that affects the root system.

In exceptional situations, it may also attract aphids, but these rarely cause significant damage and can be easily controlled.

How to propagate the tamarisk?

Sowing

• Harvest seeds from the pods at the end of summer or in autumn, once they are fully ripe. Shake the pods; if the seeds move inside, they are ready.
• Let them dry for a few days, then store them in a moisture-free place if you plan to sow in spring.
• Sow seeds in pots or directly in the ground in spring, after the last frosts. In pots, use a mix of potting soil and sand for good drainage.
• Water lightly and keep the pots in a sunny spot. Germination takes about 2 to 4 weeks.

Propagation by Cuttings

• Take semi-woody stem cuttings in summer, around July-August.
• Cut sections of 10 to 15 cm and remove the leaves from the base.
• Plant the cuttings in a mix of potting soil and sand, keeping the substrate slightly moist.
• Place them in a bright location, sheltered from drafts. Roots should form within a few weeks.

And layering? Layering of the sweetgum tree, although less common, is possible. In late spring, select a low, flexible stem, bury a portion of its length in the soil, and secure it with a stone or a staple. Keep the soil moist to encourage root formation. Once roots have appeared, separate the new shoot from the parent plant and replant it in the desired location.

Successful Associations

To create a harmonious flowerbed around the Colutea arborescens, the common bladder-senna, choose plants that thrive in sunny, well-drained soils while providing a contrast of textures and colours. The Lavandula angustifolia ‘Munstead’, with its grey-green foliage and blue-violet flower spikes in summer, pairs beautifully with the yellow-orange flowers of the bladder-senna, creating a soothing Mediterranean atmosphere. At the base of the Colutea, the santolina ‘Edward Bowles’, compact and silver, adds a touch of structure while harmonising with its creamy-white summer blooms.

The Cistus obtusifolius, with its white flowers featuring yellow centres, brings a lightness that echoes that of the Colutea, and its evergreen foliage maintains visual interest in winter. The rosemary, with its dark green foliage sprinkled with small blue flowers, not only adds an aromatic dimension to the flowerbed but also forms a beautiful contrast with the Colutea. Alternatively, the Afghan sage, such as the Perovskia ‘Blue Steel’, with its violet-blue flowers and fine foliage, creates visual depth that accentuates the bright yellow of the bladder-senna.

Finally, the Thymus praecox ‘Coccineus’, used as groundcover or edging, forms a lush, evergreen, and fragrant carpet that perfectly complements the soft, airy habit of the Colutea. Together, these plants create a natural, colourful ensemble that is perfectly suited to dry conditions, resulting in a vibrant and easy-to-maintain garden in well-drained soil and full sun.

Colutea arborescens, Lavender “Munstead’, Cistus obtusifolius, Santolina ‘Edward Bowles”, rosemary, Perovskia ‘Blue Steel’ and Creeping Thyme ‘Coccineus’