Catalpa bignonioides Nana

Catalpa bignonioides 'Nana' is an astonishing Catalpa often used in urban landscaping, but also in small gardens. This variety, grafted on a tall stem, forms a compact and flattened ball-shaped crown, similar to a vegetal parasol under which it is pleasant to shelter from the sun in summer. Its reduced growth is well adapted to small spaces, and if it does not bloom, it bears beautiful leaves with a slightly tropical appearance. This small deciduous tree with no requirements is perfect for providing shade to a terrace or a playground, preserving sunlight from October until the beginning of May.

Catalpa bignonioides, also known as the Bean Tree, Ball Catalpa or Common Catalpa, is a beautiful tree from the Bignoniaceae family: it is a cousin of climbing plants such as Campsis, Bignonia, Podranea, and other Tecomaria. Originally from the southeast of the USA, it was introduced to Europe in 1726. It is a light-loving species that appreciates rather fresh soils, tolerates limestone, and resists urban pollution very well.

The 'Nana' cultivar was selected in France by Masson nurseries around 1850. It shows slow growth, particularly compact vegetation, and smaller leaves. It is also a sterile tree that never blooms. This cultivar is most often grafted as a head on a trunk of the Catalpa bignonioides type, at about 2m (7ft 6in) - 2.50m (8ft 2in) above the ground, which gives it a characteristic silhouette of an enlarged ball placed on a massive and straight trunk, in a column. At the age of 10, this small tree will measure between 5 and 7m (16 - 23ft) in height and develop a crown 6 to 7m (19 - 23ft) wide. Its bark is grey-brown in colour, slightly channelled, and peels off over time in small flakes. Its branches are brittle, so it is necessary to protect it from strong winds. Its foliage is deciduous, appearing late in spring and falling quickly in autumn. Its leaves have an elongated heart shape, they are medium green in spring and summer, then turn yellow in autumn. Its shallow root system does not tolerate drought and makes it sensitive to strong winds. This Catalpa will benefit from being pruned severely every 2 or 3 years to remain dense. 

This 'Nana' Catalpa is suitable for both small and large gardens, but it is not recommended in situations exposed to strong winds. It is ideally planted as a standalone tree in a small city garden, in the centre of a well-maintained bed composed, for example, of ground cover roses, boxwoods, creeping Japanese spindle trees, or Lonicera nitida. Its relatively shallow root system absorbs water in summer; therefore, it is preferable to choose plants that are not demanding in terms of water, or to plant outside the perimeter delimited by its crown. Plant enthusiasts looking for vegetal umbrellas will also plant, or as an alternative, the Robinia pseudoacacia 'Umbraculifera', better suited for dry soils.