In early summer, spectacular orchid- or iris-like flowers open above bright green leaves, followed by long seed pods that dangle like string beans on the vine; in autumn the foliage turns yellow. Catalpa (Catalpa bignonioides) is grown as a fast-growing shade tree, and given full sun and soil that drains in winter, it repays with shelter in only a few years.
| Name | Catalpa |
|---|---|
| Family | Bignoniaceae |
| Type | Tree |
| Height | 26 to 32 feet (8 to 10 meters) |
| Exposure | Full sun |
| Soil type | Ordinary |
| Leafage | Deciduous |
| Blooming | Mid-summer |
This fast-growing tree is also very hardy in winter.
Catalpa is an easy tree to grow. It will settle in properly in any type of soil, even though, as for most trees, it prefers well-draining soil.
The Orchid flower tree is extremely ornamental: in spring and summer, bright green leaves and nice flowers strike home. In fall, leaves turn a beautiful yellow hue. Try to find a spot for it apart from other trees so you can highlight its beauty.
This tree loves sunlight, which makes it an excellent shade tree.
Catalpa is a fast grower, which makes it ideal if you’re planning a shaded spot in the garden to savor in only a few year’s time.
Though Catalpa will do perfectly fine without any pruning at all, it’s possible to prune it now and then for maintenance.
Indeed, Catalpa starts growing with a thin, upright figure that tends to round off with age.
If it’s properly settled in, you can go for years without caring for the tree at all.
Perhaps only a little watering in summer during the first and second year will help it spread its roots, depending on the climate and weather.
In dryer areas, mulch the tree around the trunk and all the way to where midday sun lays shade.
Though there are several species within the Catalpa genus, the one you’re likely to come across it Catalpa bignonioides.
Native to North America and Asia, Catalpa is a wonderful tree thanks to its blooming shown in the picture above/right. It also works wonders as a cool shade tree.
Spectacular and abundant flowers appear in early summer, signaling the time to start taking advantage of the shelter Catalpa provides from scorching heat.
These bean-like pods are what gave the tree its name: in the Cherokee language, the word ‘Catalpa’ is a type of bean plant.
Growth is rapid, and will speed up even more if planted in a warm spot.
Beyond the common Indian bean tree, nurseries offer golden, purple and variegated forms, plus a mop-headed one small enough for a modest garden. The table below compares the catalpas you are most likely to find for sale.
| Variety | Foliage | Habit and size band | Flowers | Best for |
|---|---|---|---|---|
| ‘Aurea’ | Bright golden yellow | Medium, rounded; can be coppiced | White, spotted throat, sparser than species | Foliage colour; a lit-up focal point |
| ‘Variegata’ | Green splashed cream and white | Medium, rounded | White, spotted throat | Brightening a shaded corner |
| ‘Purpurea’ | Blackish purple young leaves, ageing green | Tall, vigorous | White, spotted, in large heads | Dark foliage contrast; hard-pruned for leaf size |
| ‘Nana’ | Green, dense | Dwarf mop-head on a grafted stem | Rarely flowers | Small gardens, drives and formal pairs |
| ‘Koehnei’ | Green with yellow central blotch | Medium to tall | White, spotted throat | Variegation without full gold |
| ‘Pulverulenta’ | Green finely speckled white | Medium, rounded | White, spotted throat | Dappled, shimmering effect close up |
| ‘J.C. Teas’ | Green, three-lobed on young growth | Tall, vigorous hybrid | White, abundant, later than species | Fast shade where space allows |
Three main diseases may affect a weakened Catalpa tree. These are all fungal diseases.
Verticilium wilt – Often fatal. Purple-gray streaks appear on wood when a branch is snipped. Leaves wilt, usually along an entire branch or along the sap-flow to one side of the tree.
Leaf spot – Many possible culprits here. Usually the main fungus is Anthracnose, caused by Gloeosporium catalpae, but others also may appear.
Three fungal diseases account for most trouble on a weakened catalpa. The signs they leave on wood and leaves make them easy to tell apart, and each calls for a different response.
| Disease | What you see | How serious | What helps |
|---|---|---|---|
| Verticillium wilt | Purple-grey streaks in the wood when a branch is snipped; leaves wilt along a whole branch or one side of the tree | Often fatal | High-nitrogen natural fertilisers, so a growth spurt buries the fungus under new wood |
| Powdery mildew | Dusty white powder on leaves, near the leaf veins | Disfiguring, appears in warm, moist weather | Powdery mildew treatment as used on other trees |
| Leaf spot (anthracnose) | Spots on the leaves, usually caused by Gloeosporium catalpae | Many possible culprits, rarely fatal | Bordeaux mixture if the fungus spreads too much |
In every case, a strong, well-fed tree is the best defence.
During the first few years, spread mulch at the base of the tree to stimulate its growth.
