How to Grow and Care for Catalpa

The catalpa tree (Catalpa spp.) is well-loved and recognized for its height, enormous heart-shaped leaves (up to 12 " long and 8" wide), twisted spreading branches, panicles of creamy white fragrant blossoms, and long dark brown seed pods. Though its tendency to spring up in odd places and grow rather quickly has earned it a reputation of being a bit of a "weed tree," plenty of folks love having this large graceful shade trees on their properties. They became popular at the turn of the century in the Northeast US and one often sees streets or cul-de-sacs named some variation "Catalpa Terrace" or "Catalpa Circle."

Also known as southern catalpa, hardy catalpa, western catalpa, northern catalpa, catawba, cigar tree and caterpillar tree, it is native to a wide-ranging area including North America, the Caribbean and East Asia. It's been cultivated throughout the US since the early 1800s. The flowers are attractive to bees, butterflies, and hummingbirds for pollination, and this tree is the sole host for the catalpa sphinx moth. With dense foliage and large leaves, the catalpa provides excellent cover and shelter for a wide variety of song birds and wildlife. The tree's hardiness once made it an important source of lumber, particularly for railroad ties and fence posts. It's seen in many large parks due to its hardiness and graceful shape in the landscape, but as an urban tree the leaf litter can be somewhat problematic near sidewalks and cars.

Common Name	Catalpa, catawba, cigar tree, western catalpa
Botanical Name	Catalpa spp.
Family	Bignoniaceae
Plant Type	Deciduous tree
Mature Size	40 - 60 ft. tall, 20 - 40 ft. spread
Sun Exposure	Full sun to part shade
Soil Type	Clay, loam, sandy, moist, dry
Soil pH	Tolerates acidic to alkaline
Bloom Time	Late May to June
Flower Color	White
Hardiness Zones	USDA 4-8, depending on species
Native Areas	North America, Caribbean, East Asia

Care of Catalpa Trees

The catalpa is remarkably adaptable to a wide range of soil, moisture and weather conditions, and thought 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

The catalpa tolerates a wide range of soil conditions, from acidic to alkaline, wet clay soils, sandy, loam and more. Good drainage is always preferred but the catalpa 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 )
• Chinese catalpa (Catalpa ovata), also known as yellow catalpa
• Haitian catalpa (Catalpa longissima)

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. The seeds (from the pods) should be sown in fairly warm temperatures between 60-70 degrees Fahrenheit, and sowed on the surface of a light peaty soil mix, rather than covered in soil. You can collect the seeds in fall, keep refrigerated, then plant in spring and transplant the seedlings when they're 3-4 inches tall. Mist lightly with water and they will germinate within 14-30 days. You can direct sow the seed after last frost in spring, or in winter in a cold frame, sunny window or greenhouse.

Common Problems with Catalpa Trees

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. They can also be can be propagated from cuttings taken during the summer from non-flowering branches.

Although prone to 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, catalpa trees are fairly resilient, weathering pests and diseases to grow well each year.