The Catalpa bignonioides is native to the southeast of North America. This tree often grows along streams and river banks. The Catalpa bignonioides is commonly named southern catalpa, Indian bean tree or cigar tree because of the seeds pods. The southern catalpa is a genus from the Bignoniaceae family.
The Catalpa bignonioides has a broad-rounded, irregular, loose crown. Because the crown is situated quite low (short trunk) this tree is not very suitable near a street or road. The southern catalpa looks its best as a solitary.
The leaves are green and heart-shaped and can get op to 8 inches (20 centimetres) wide. The leaves appear late in spring. In autumn the leaves turn partly yellow and fall off quite early.
In June the white, trumpet shaped, fragrant flowers appear that attract bees and butterflies. They have brown/purple and yellow markings in the throat. The flowers appear on many-flowers upright panicles above the leaves. The tree needs to be about 4 years old before it will bloom. After the bloom the bean or cigar like pods are formed in which the seeds grow. The fruits are green at first and then turn brown. They stay on the tree during winter. In spring they split open to release the seeds. The seeds are brown and flat and have two papery wings. The seeds germinate easily.
Next to multiplying through seed it also readily multiplies from cuttings. You can place a new branch in some water or into the ground and roots will grow soon.
The Catalpa bignonioides is a messy tree because of the spent flowers that drop off. They are a bit slimy and can make the pavement temporarily slippery. Then there are the remains of the pods that, after splitting open, fall to the ground and the leaves that fall in autumn.
The Catalpa bignonioides grows fast when its young. In own season it can grow at least 3 feet (1 metre) longer. Older trees grow less fast. The roots spread wide and relatively close to the surface. The main roots grow deep into the ground. The southern catalpa is a tough tree and can easily be pruned.
The Catalpa bignonioides has brittle branches which is why it has problems with too much wind. Also the large leaves can easily be damaged by strong winds and hail. The southern catalpa likes a sheltered and warm spot and prefers well drained soil. It tolerates paving. The Catalpa bignonioides does not like salt, but can grow in almost every environment. The Catalpa bignonioides is well equipped against occasional flooding because of the wide spreading roots which give it good grip. Because of the extensive root system it can stabilize the soil and prevent erosion.
Cats like to sharpen their nails on the trunk. I have placed some chicken wire around the bottom of the trunk to protect it. Otherwise there will not be any bark left.
The leaves of the Catalpa bignonioides ‘Aurea’ are purple in the beginning, then they become golden yellow and later in the year they turn green. Aurea is Latin and means golden or yellow. That refers to the colour of the leaves. The Catalpa bignonioides ‘Aurea’ remains smaller than the Catalpa bignonioides with a height of 26 feet (8 metres).
The Catalpa bignonioides ‘Nana’ is umbrella shaped because it is grafted. Nana is Latin for dwarf. It is also commonly named dwarf southern catalpa and only reaches a height of about 16 feet (5 metres) instead of the 49 feet (15 metres) of the Catalpa bignonioides. The Catalpa bignonioides ‘Nana’ is usually pruned every year and does not bloom. The best period for pruning is at the end of November or at the beginning of March as long as it does not freeze. Cut the branches at about 6 inches (15 centimetres) above the graft. Because of the pruning and the grafting this dwarf southern catalpa forms a denser crone than the Catalpa bignonioides and the Catalpa bignonioides ‘Aurea’. Unfortunately the Catalpa bignonioides ‘Nana’ is often falsely called Catalpa bungei. The Catalpa bungei is also a small catalpa but the Catalpa bungei (native to northern China) does bloom.
Exposure: sun/part shade
Foliage colour: green
Flower colour: white
Flowering time: June - July
Hardiness: -20 ºC (-4 ºF)
Height: 49 feet 3 inches (15 m)