Catalpa bignonioides ‘Nana’ – Dwarf Indian Bean Tree
Catalpa bignonioides ‘Nana’, also known in the nursery trade as Catalpa bungei ‘Nana’, is a compact form of the Indian bean tree grown for its large heart-shaped leaves and naturally rounded crown.
Being a compact version, this makes Catalpa Nana particularly useful as a small garden tree, for front gardens, patios and formal planting where a full-sized Indian bean tree would eventually become too large.
Its main feature is its foliage. The leaves are large, green and distinctly heart-shaped, creating a lush, dense and rounded canopy during summer creating some welcome shade. Catalpa is naturally late into leaf in spring, so it may still appear dormant after many other garden trees have started growing. In autumn, the foliage usually turns yellow before falling in autumn. [1]
Of the other small trees for small gardens, this is one that makes a big statement with just the foliage as it rarely produces flowers or bean pods unlike other ornamental trees. [1][2] Occasional flowers have been recorded on mature, largely unpruned specimens, but they should be regarded as an exception rather than an expected feature. [4]
Listed as generally pest-free[1]
How Big Does Catalpa Nana Grow?
Professional tree growers generally give an eventual height of around 4–6m, with an unpruned crown potentially reaching around 5–7m across. [2] Its crown can be kept considerably smaller by periodic pruning, making it suitable for gardens where its full natural spread would be too large.
How Fast Does Catalpa Nana Grow?
Catalpa bignonioides ‘Nana’ is relatively slow-growing, typically making around 20–30 cm of new growth a year when young, with its growth slowing considerably as it matures. [5] A useful real-world example is provided by the German Dendrological Society, which records four Catalpa bignonioides ‘Nana’ planted around 1980. When measured in May 2025, at approximately 46 years old, they were around 4 m high with crowns approximately 4 m across. [6]
Where Should You Plant Catalpa Nana?
Choose a sunny, reasonably sheltered position with enough room for the crown to develop unless you are happy to cut it back. A sheltered position is ideal as strong winds can damage the foliage and brittle branches. Sheltered means protected from strong prevailing winds by buildings, hedges, trees or fencing. Avoid exposed hilltops, open fields, coastal sites and positions where wind is funnelled between buildings.
Catalpa Nana works particularly well:
- as a feature tree in a lawn
- in front gardens
- beside patios or paths
- in courtyards
- as a pair beside an entrance
- in formal rows
- within borders where the clear stem allows planting underneath
Full sun is best, although some partial shade is tolerated.
Catalpa Nana grows well in a wide range of ordinary garden soils with heavy clay, loam, sand and chalk listed as suitable, and acid, neutral and alkaline soils all tolerated. [1] If you want to give it ideal conditions use neutral to slightly acidic soil that is reasonably fertile and moisture-retentive but well- drained. The species is documented growing well at pH 5.5–7.0, although it can tolerate more alkaline conditions. [7][8] Avoid permanently waterlogged ground.
Listed as H6, which means it is hardy down to -20°C [1], and translates to plant almost anywhere in the UK in terms of temperature.
Water well for the first two growing seasons and during extended dry spells as the tree is then considered to be generally established.
Pruning Catalpa Nana
Catalpa Nana naturally forms a rounded crown and does not need regular clipping simply to maintain its shape. However, the crown can be pruned in late winter or early spring if you want to restrict its spread or maintain a tighter, more formal head. Always cut out dead, diseased or crossing branches.
It responds well to substantial pruning, which is why older specimens are sometimes periodically cut back hard to renew the crown. [2]
Always remove anything growing below the graft union.
Are Catalpa Nana Roots a Problem?
Catalpa bignonioides ‘Nana’ has a shallow, fleshy root system rather than a strongly deep-rooting one. [2] Standards are normally grafted onto Catalpa bignonioides rootstock, and the species is described as having an extensive root system, so the roots should be expected to spread laterally beyond the immediate base of the tree. [2][10]
As with many other spreading rooted trees, the shallow roots of Catalpa bignonioides may cause problems with hard surfaces, particularly where soil volume or aeration is poor because it forces the roots to grow even shallower. [9] This is primarily a consideration close to the tree: RHS guidance states that most lifting of patios and drives by tree roots occurs within about 1 m of the trunk. [12]If the planting conditions are good, you are unlikely to have this problem, and if you do, it will likely only be close to the tree.
This should not be confused with a high risk of structural damage to houses. The RHS lists Catalpa among trees with low water demand and states that tree roots are unlikely to penetrate sound foundations directly. On shrinkable clay soils, the risk of subsidence generally increases with tree size and proximity to the building, but Catalpa is not regarded as one of the high-water-demand species. [12]
Can Catalpa Nana Grow in a Pot?
Catalpa bignonioides ‘Nana’ can be grown long term in a large container. [2] Use a substantial, stable pot with good drainage and a soil-based peat-free compost such as John Innes No. 3. [13] The larger the pot, the fewer the problems you will likely have with it. We suggest an absolute minimum of 50L with 100L or more being much better.
Keep the compost moist but not waterlogged, as container-grown trees dry out much faster than those planted in the ground. [13] Feed during the growing season and replace the top 5 cm of compost each spring with fresh compost and controlled-release fertiliser. [13] A sheltered position is preferable because the broad crown can catch strong winds. [2] For long-term growth, planting in the ground is generally the easier option.
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