Catalpa: Care and Growing Guide

Care of Catalpa Trees

The catalpa is remarkably adaptable to a wide range of soils, and though it needs a good amount of sunlight, it’s not fussy about its growing conditions.

Light

The catalpa does best with at least four hours of direct sunlight per day. It prefers full sun to really thrive.

Soil

Catalpa trees tolerate a wide range of soil conditions, from acidic to alkaline, wet clay soils, sandy, loam and more. Good drainage is always preferred, but catalpa trees can survive both flooding and extended periods of drought.

Water

This tree tolerates drought as well as heavy rains and flooding and is not subject to problems from extremely wet or dry weather.

Temperature and Humidity

Being native to warm, temperate zones, the catalpa has a somewhat narrow growing zone range of 4 to 8 (depending on species) but is a reliable deciduous tree that can tolerate cold winters and hot summers fairly consistently. It’s not overly bothered by high humidity or dryness.

Fertilizer

If your soil is fairy moist and rich, such as loam with good drainage, you won’t need fertilizer for your catalpa.

However, when planting in clay, silty or sandy soil, or in dry soils, you should consider applying a standard 10-10-10 fertilizer a few weeks after planting, to give it a good start and promote healthy growth.

Types of Catalpa Tree

There are two main species of catalpa tree grown in North America, the northern catalpa and southern catalpa, both of which are fairly similar. The Chinese catalpa is a somewhat different species with yellow flowers, also known as yellow catalpa.

All three are commonly planted outside their native areas as ornamental landscape trees.

• Northern catalpa (Catalpa speciosa) has somewhat larger seed pods, leaves and flowers than the southern catalpa.
• Southern catalpa (Catalpa bignonioides) is native to the Southeast U.S. and is often cultivated as a garden tree.
• Chinese catalpa (Catalpa ovata), also known as yellow catalpa, has yellowish flowers.
• Haitian catalpa (Catalpa longissima) is known for its pink-leaning flowers.

Pruning

Catalpas should get regular pruning in youth to ensure good stable growth and good form. Start pruning at one year for new trees. Trim away suckers from the base, and trim large lower branches with a pruning saw to promote a straight, central “leader” trunk.

As the catalpa grows, keep lower branches trimmed to allow for easier maintenance at the base of the tree. Pruning is best done in early spring after blooming or late fall.

Propagation

Though they grow quickly, it takes about five to seven years for catalpas to reach maturity to the point where they blossom and bear seed pods each year.

Some varieties, such as the Haitian catalpa, begin producing flowers in the first two years of maturity. They can be grown from soft root cuttings or branch cuttings, or from seed. They also reseed freely in most areas where they are established.

How to Grow Catalpa from Seed

Catalpa trees grow easily from seeds, which germinate fairly rapidly without any special treatment. You can direct sow the seed after last frost in spring, or in winter in a cold frame, sunny window or greenhouse.

1. Collect the seeds in fall, and keep them refrigerated.
2. In spring, put seeds directly on the surface of potting soil.
3. Keep the soil moist and wait for germination, in a spot with average room temperature.
4. Move the germinated seeds to a sunny spot.
5. Maintain moist soil until the seedlings are about 3 to 4 inches tall, which is when you can transplant them.

Common Pests & Plant Diseases

Catalpa trees are fairly resilient, weathering pests and diseases to grow well each year. They do sometimes struggle with pests, like the larva of catalpa sphinx moth, which can defoliate the tree, and some diseases, such as powdery mildew, leaf spot, and twig blight,

Common Problems with Catalpa Trees

Messy Seed Pods

The catalpa’s seed pods appear in autumn. While beautiful on the tree and lending seasonal interest, these seed pods are fairly messy and may be slippery to pedestrians, so these trees should not be planted near sidewalks or parking lots.