Chitalpa tashkentensis: planting, pruning, care

Botany

The Chitalpa, also known as Chitalpa of Tashkent, is a large bush or small deciduous tree from the Bignoniaceae family. It is a hybrid resulting from cross-breeding between Chilopsis linearis (desert willow) and Catalpa bignonioides (Catalpa). It combines characteristics of both species, offering better drought tolerance than Catalpa and more spectacular flowering than Chilopsis. Native to the United States, Chitalpa is mainly found in warm, dry regions such as the southwest coast and northern Mexico. It adapts well to Mediterranean climates in our country.

The genus Chitalpa includes only one recognised species, Chitalpa tashkentensis, although specific cultivars have been developed to enhance certain characteristics like flower colour or disease resistance, such as ‘Pink Dawn’ and ‘Morning Cloud’, known for their abundant pink and white flowers respectively.

Its size typically ranges between 3 and 10 metres in height with a spread of about 7 metres. Its form is upright with a rounded, often spreading crown, providing pleasant shade.

The foliage of Chitalpa is deciduous, meaning it loses its leaves in winter. The leaves are single, lanceolate and tapered, resembling a lance. They are olive-tinged green and measure between 10 and 20 cm long, contributing to the tree’s lush appearance. This abundance of leaves gives Chitalpa a bushy yet airy silhouette, ideal for creating shade in a garden.

The foliage of Chitalpa tashkentensis

In summer, Chitalpa reveals its spectacular flowering. The tree is adorned with clusters of tubular pink or white flowers, appearing at the branch tips, from late spring to summer, typically from May to September depending on the climate. Under certain conditions, a second flowering may occur in September, thus extending the flowering period. The flowers of Chitalpa are grouped in conical, upright racemes appearing at the tips of branches. They resemble those of Catalpa, one of its botanical parents, in shape and arrangement. They are usually trumpet-shaped, with fused petals forming a tube at the base and opening into a corolla. They measure about 3 cm wide, and have a tubular, campanulate shape. They consist of five distinct lobes: three wider lobes at the lower part and two smaller ones with very undulate margins at the upper part. Their colour is mainly pale pink, often tinged with mauve, creating subtle shade variations. The throat of the flowers is streaked with pale yellow and purple, adding vivid contrast. Being sterile, they do not produce seeds.

The flowering is abundant and long-lasting, continuing through summer, sometimes until the first frosts, and appreciated by many pollinators such as bees and butterflies, attracted by the nectar and sweet fragrance they emit.

Chitalpa offers beautiful soft pink flowers

Species and main varieties

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Planting the Chitalpa

Where to Plant It?

Hardy down to -18°C and drought-resistant, the Chitalpa adapts well to all regions. This beautiful ornamental bush thrives in any ordinary soil but prefers well-drained, loose, and deep soils, even chalky ones. Once established, it withstands drought perfectly, making it ideal for areas with dry summers. To optimise its growth and flowering, it’s best planted in full sun. In very hot climates, it can also be placed in light shade.

Its relatively fast growth and dense habit make it an excellent choice for creating free-flowering hedges or filling out the back of flower beds. Planted as a standalone, the Chitalpa can be used to shade a terrace. Thanks to its average height, usually between 5 and 10 metres, and its rounded, spreading crown, it provides pleasant shade during hot summer days. If grown as coppice shoots, with multiple trunks, the Chitalpa offers a broad, bushy shape, ideal for large gardens or parks.

When to Plant It?

The ideal time to plant the Chitalpa is in spring, from March to May, or from September to November in milder regions. Prepare the soil by working it well to ensure good drainage.

How to Plant the Chitalpa?

In the Ground

• Start by loosening the soil deeply
• Soak the root ball in a bucket of water to moisten it thoroughly.
• Dig a hole twice as wide as the root ball
• Add drainage materials (gravel, coarse sand, etc.) if the soil is clayey
• Place the root ball in the hole, ensuring the collar of the bush is level with the ground
• Install a stake if needed to keep the bush upright
• Fill in with garden soil, mixed with a few spadefuls of horticultural sand, good compost, and compost
• Tamp down lightly
• Water generously after planting
• Spread a layer of mulch around the base to maintain moisture around the roots
• Continue to water regularly for the first two years

In a Pot

Smaller Chitalpas (such as ‘Summer Bells’) will make a striking feature in a large pot on the terrace.

• Choose a sufficiently large container, at least 65 cm in height
• Line the bottom of the pot with clay pebbles or pumice for drainage
• Plant the bush in a mix of soil, sand, and good compost
• Water at planting, then regularly thereafter
• Repot every two years into a larger pot

Pruning and maintenance

Once well established, the Chitalpa requires no specific maintenance. Water-efficient, beyond the first two summers after planting, there’s no need to water it, even in hot and dry climates. Simply add compost annually by lightly working it into the soil at the base of the plant at the start of the growing season to encourage growth.

Easy to cultivate, this tree is disease-resistant when grown in favourable conditions. In waterlogged or poorly drained soil, it may become susceptible to fungal diseases such as root rot, which causes the roots to decay.

How to prune a Chitalpa?

The Chitalpa doesn’t require specific pruning, simply remove dead branches or those disrupting the bush’s habit after flowering. During the first few years, pruning in March may be necessary to establish a strong, well-balanced framework. In summer, remember to deadhead spent flowers to encourage further flowering.

Propagation

Chitalpa is mainly propagated by cuttings, a quick and reliable method. Herbaceous cuttings taken in summer or semi-hardwood cuttings in autumn usually give good results.

• Select a healthy, vigorous stem about 15 cm long
• Remove the leaves from the lower half of the stem and cut the upper leaves in half
• Then plant the cutting in a mix of compost and sand, kept moist
• Place the cutting under a cold frame, protected from direct sunlight
• After a few weeks, roots should start to form
• Keep the substrate moist until rooting occurs, which takes 1 to 3 months
• Once the cutting is well-rooted, it can be transplanted into a larger pot
• Plant your cuttings in the ground after one or two years of pot cultivation

Uses and Associations

The Chitalpa tashkentensis is a versatile tree that can be integrated into the garden in various ways. With its slightly exotic yet rustic charm, it thrives almost anywhere in the garden, at the back of a perennial border or in a loose hedge, near the terrace to provide shade.

It pairs beautifully in flowering hedges with ceanothus, buddleias, weigelias, hibiscus, viburnums or lavateras, as well as with Japanese cherry trees, lilacs, and Chinese almond trees which will flower before it. It creates a lush, flowering backdrop for bush roses. Pair the Chitalpa with evergreen bushes, such as evergreen ceanothus in mild climates or boxwoods, which will take over when it sheds its leaves in winter. The light, airy appearance of ornamental grasses like miscanthus and stipas contrasts beautifully with the density of its foliage.

Its flowering will be particularly highlighted in a setting of silvery foliage, surrounded by artemisias, lavenders, and Festuca glauca. In a lush shrub border, its delicate flowers will complement those of hydrangeas (in not-too-dry climates), yarrows, or the more delicate blooms of gaura and masterworts. The umbel flowers of purple or white agapanthus will add a touch of elegance and verticality, harmonising with the Chitalpa’s summer flowering.

Buddleia davidii ‘Pink Delight’, Chitalpa tashkentensis (photo: Wendy Cutler), Ceanothus delilianus ‘Gloire de Versailles’, Rose ‘Red Ballerina’