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If you are looking for an insect-friendly ornamental plant for the garden that defies climate change and also gets by with few nutrients, the bladder bush is the right choice.

Bladder
The bladder bush is a bee-friendly, low-maintenance eye-catcher for many gardens

It's not just the inflated legumes that make bladder bushes (Colutea) special plants. The long flowering period, the drought tolerance and the ability, thanks to a symbiosis with bacteria, to fix nitrogen as fertilizer from the air itself, speak in favor of this special tree. In this article, you'll find out everything you need to know about growing bubble bushes in the garden, from the right location for bladder bushes, to pruning and care - to answering the question of whether Colutea arborescens is poisonous is.

Bladder bush: origin and characteristics

The bladder bushes (Colutea) form a genus with about 26 species within the legume family (Fabaceae). Like most legumes, bladder shrubs form a symbiosis in their root zone with bacteria that can fix nitrogen from the air. Therefore they do not need to be fertilized with nitrogen.

The common bladder bush (Colutea arborescens) is the most common here. It is also called yellow bladder bush or common bladder bush and originally comes from the Mediterranean and North Africa. In Germany it only occurs naturally on the Upper Rhine, but can also be found in other places in the wild.
The growth of bladder bushes is rather slow and sprawling. They grow to a maximum of 2 to
4 m in height and just as wide. Their root system is rather shallow. In the fall, bladderbushes shed their leaves, which are imparipinnate, with elliptical leaflets about 3.5 cm long. The bladder bush flowers from May to August. Therefore, one can admire the typical butterfly flowers, which are yellow-orange in the common bladderbush, over a relatively long period of time. The fruits of the bladder bush also have a high ornamental value, because they are inflated pods that are 3 to 6 cm long. Inside are 20 to 30 black,lentil-like seeds.

The bladder bush grows slowly, bushy and doesn't get too big

Is the bladder bush bee friendly? In general, bladder bushes are very insect-friendly plants, especially thanks to their long flowering period. However, it is not so easy for many insects to get the pollen, which is why larger wild bees are more likely to be found on bladder bushes. These include, for example, bumblebees (Bombus) or carpenter bees (Xylocopa). One insect that requires the bladderbush to survive is the endangered bladderbush blue (Iolana iolas) - a butterfly whose caterpillars develop in the pods of bladderbush.

Bladder bushes are more likely to be visited by larger insects

The most beautiful bladder bush varieties

In addition to the common bladder bush, there are only a few other species and varieties here. This small list will help you choose the right shrub for your garden.

Common Bladder (Colutea arborescens): Common Bladder is the leading species of the genus Colutea . It grows to a height of 3 to 4 m, tolerates temperatures down to - 23 °C and impresses with its yellow flowers and a long flowering period.

Oriental Bladder Bush (Colutea orientalis): Colutea orientalis is also called Red Bladder Bush , although its flowers are more orange-yellow. With a maximum height of about 2 m, it is the smallest of the bladder bushes presented here. Similar to the common bladder bush, Colutea orientalis is also hardy to around - 20 °C.

The flowers of the Oriental Bladderbush are darker and have a red tinge

'Copper Beauty' bladder bush (Colutea x media 'Copper Beauty'): 'Copper Beauty' bladder bush variety is a hybrid, i.e. the crossing of two different species - in the case of Colutea x media between Colutea arborescens and Colutea orientalis. Its yellow-orange to copper-colored flowers are special. Unfortunately, 'Copper Beauty' is a little less hardy and can only tolerate temperatures down to around -17 °C.

Tip: Confusion can also occur with bladder bushes. Less in terms of appearance than in terms of name. On the market there are, for example, the bladder tree (Koelreuteria paniculata) and the bladder spitter (Physocarpus opulifolius), but these are plants from completely different species families.

Bubble
The bubble tree lives up to its similar name

Plants: location and procedure

Bladder bushes do well in places where many other plants struggle. An optimal location for bladder bushes should be sunny and have well-drained, lean and rather calcareous soil. Even wind and s alt don't bother blister bushes.

The best time to plant bladder bushes is in autumn, regardless of whether they are in containers or bare-rooted plants. Plants from pots in particular can be planted in the ground from April.
You can adjust the planting distance to suit your preferences. You can have bladder bushes as a solitary eye-catcher in the garden if there is enough space, but you can also integrate them into insect-friendly hedges. Then ensure a minimum planting distance of at least 50 cm.

Bubble shrubs are good for insect friendly hedges

Once you have chosen a suitable location, you can plant your bladder bush.

  1. Dig the planting hole. It should be so deep that the plant later sits as deep in the ground as it did in the pot.
  2. Especially with humus-rich, loamy soils, it is advisable to mix the excavated material with our Plantura lawn sand or expanded clay and some garden lime such as our Plantura lawn & garden lime. Because the bladder bush otherwise only thrives unsatisfactorily on soil that is too fertile. Our products are shipped CO2-compensated and come to you with many useful tips for professional use.
  3. Place the bladder bush in the planting hole and fill it up with the excavation.
  4. Tighten the soil around the bush and water well. Especially in the early days, when the root system is not yet sufficiently developed, bladder bushes also need a little more water. By modeling a casting ring out of soil, you prevent the irrigation water from simply running away.
  5. In the first year, make sure that the shrub does not get too cold. Protection is provided, for example, by a layer of mulch on the root ball or a jute bag that is placed over the bush.

Care of the bladder bush

Hardly any plant in the garden requires less care than a bladder bush.
You should only use a watering can during extremely dry periods. Since the bladder bush comes from the Mediterranean region, it gets along very well with little water and, on the contrary, even reacts with stunted growthon soil that is too moist.
You don't even have to fertilize your bladder bush. Thanks to the symbiosis with nodule bacteria, the shrub itself ensures a sufficient supply of nitrogen. Additional fertilization would stimulate growth, but at the same time make the shrub more susceptible to frost - because fresh, young tissue is usually the first to be destroyed by frost.

Even in dry natural locations, the bladder bush receives little attention

Pruning bubble bushes is not absolutely necessary, but can always be done if you want to keep the bush young. For this you can cut off some of the old shoots at the base every few years in spring. However, this should not be more than a third of all shoots. Annual shoots can also be shortened in spring before they sprout.

Our soils are usually rather acidic. Therefore, regular liming is part of the care of the bladder bush. We recommend carbonated lime for this, such as our Plantura Lawn & Garden Lime, as it has a longer-lasting effect. The easiest way to determine when it is time for the next liming is to measure the pH of the soil. If this is below 6.5, it is time for the next liming.

Care at a glance:

  • Water only during extreme dry periods.
  • Fertilizing is not necessary.
  • In the spring you can prune the bladder bush if you want to influence its growth.
  • Liming should be done when the pH of the soil falls below 6.5.

Is the bladder bush hardy?

The bladder bush is hardy here because it can withstand temperatures down to - 23 °C. However, since this varies slightly from shrub to shrub, very cold winter nights can sometimes affect some bladder shrubs as well. It therefore does no harm if you protect the rootstock with a layer of mulch, for example made of leaves or our Plantura organic pine bark.

Mulch
A layer of mulch insulates and protects the rootstock

Propagation

The easiest way to propagate the bladder bush is by seeds or cuttings.

Sow bladderbush seeds either directly on the spot or in small pots. In the fall, collect the black seeds found in fallen pods and store them in a dark, dry, rather cool place through the winter.

  1. In February it's time for sowing. To do this, soak the seeds for approxSoak in water for 10 hours.
  2. Fill small pots of about 8 - 10 cm in diameter with moistened potting soil, for example with our Plantura herb and seed soil.
  3. Put 2 to 3 bladderbush seeds about 1 cm deep in the soil.
  4. Place the pots in a bright place with a temperature of around 20 °C.
  5. In the next few days, make sure that the substrate does not dry out. The seeds should germinate after 10 to 20 days.
  6. If more than one seed has germinated per pot, you should remove the weaker seedlings at a height of about 3 cm and leave only the strongest.
  7. Once the plants are about 10 cm high, they can be planted out in their final location.
In winter the legumes open and the seeds can fly out

Propagation via softwood cuttings is also possible. To do this, cut off approximately 10 cm long shoot tips without flowers from your bladder bush at the end of spring. Remove the lower leaves from the cutting, leaving only the top 5 cm. The cuttings are then placed in small pots filled with moist growing soil. If the leaflets then hang on the ground, they are shortened to a more practical length. In the near future it is particularly important that the substrate is constantly moist. In addition, the cuttings should be in a light and warm, but not hot place. Drying out can be prevented by putting plastic bags over the pots and fixing them with a rubber band. However, it is important to air under the bags at least twice a week. When the cuttings are rooted, they are planted individually in about 9 cm pots. The fresh growth is later pruned to achieve bushy branching.

For cuttings, choose green shoot tips without flowers

Is Bladder Bush poisonous?

Not only the yellow bladder bush is slightly poisonous. Accordingly, the consumption of plant parts of the other species of Colutea can lead to slight symptoms of poisoning such as nausea and vomiting. Bladder bushes are also poisonous for horses, dogs and cats, which manifests itself in gastrointestinal complaints and diarrhea, as in humans.

Are you looking for other ornamental plants for dry, lean locations? Then you might be interested in rue (Ruta graveolens).

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Trees