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Are catalpa trees hard to grow? | Source: JamesDeMers/Pixabay |
The Tree With Long Seed Pods
The catalpa tree is an ornamental shade tree that produces dense clusters of white flowers and long seed pods. Depending on the species, they can grow anywhere from 20 to 70 feet in height, with Northern Catalpas being the tallest and most commonly reaching 50-60 feet.
There are three common catalpa species—two North American and one Chinese:
- Northern Catalpa (Catalpa speciosa): Native to the midwestern United States
- Southern Catalpa (Catalpa bignonioides): Native to the southeastern United States
- Chinese Catalpa (Catalpa ovata): Native to western China
Because they are hardy plants that require very little water—and are decorative— they are often grown outside their native regions.
Catalpas are deciduous trees, meaning they shed their leaves annually—usually in the fall or after the first frost. During this time, they also shed their long seed pods and flowers, which can deter some people from growing the tree.
However, catalpas have many wonderful qualities as well. With their broad, heart-shaped leaves and striking, orchid-like blossoms, they offer a unique touch of elegance to any landscape. They are hardy trees that grow quickly, provide shade, and attract wildlife.
Let's explore the details of cultivating these magnificent trees, from selecting the right variety and planting techniques to maintenance tips and troubleshooting common problems.
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Catalpa fruits are long, slender, and resemble bean pods | MONGO/Wikimedia Commons, CC0 |
How to Grow a Catalpa Tree From Seed
You can grow a catalpa tree from cuttings, but it's easier to grow them from seeds.
1. Collect the pods and store them in a cool, dry area.
Collect the pods after the leaves fall—typically in late fall or early winter—once the pods are sufficiently dried but before the seeds have fallen from open pods. Store the pods in a cool, dry area. When you're ready, the seeds may be separated from the pods and placed in packets.
2. Plant the seeds in a pot with good drainage.
Catalpa trees grow best with low moisture, so make sure the pot or ground soil has good drainage.
Fill the pot with potting soil (pH 5.5–7, slightly acidic to neutral) and place a few seeds on top. Lightly cover the seeds with more potting soil—no more than 1 inch in depth.
If you choose not to grow them in a planter, plant the seeds in the spring in warm, loose, and rich soil.
3. Lightly water the seeds, and place the pot in a shaded area.
The young seedlings won't be able to handle the intensity of full sunlight yet, so keep them in a shaded area with mild temperatures (60–70ºF).
Continually monitor the seedlings and keep the soil moist but not soaked.
4. Transplant the seedlings into progressively larger pots.
Within a couple of months, the seedlings will be a few inches tall with one or two leaves. You can certainly transplant them to the desired permanent location, but it is recommended to continue growing them in pots over the first winter. This makes it easier to care for the young plant and to prevent weeds, pests, and diseases from damaging it.
Use fresh potting soil each time to ensure the plant gets enough nutrients. No fertilizers are required.
5. Transplant the tree into your garden or lawn.
Spring is the best time to move the young catalpa to its permanent home. Choose a location that receives full sunlight or only partial shade. While young seedlings need protection from intense sun during their first few months, mature catalpas thrive in full sun locations.
Again, the soil should be slightly acidic and have good drainage. Dig a hole that's a little larger and wider than the pot the seedling is in. Remove any roots, weeds, or other debris.
Carefully remove the seedling and place it in the hole. As you cover the roots with soil, adjust the roots so that they point outwards and downwards. This ensures healthy growth and prevents the roots from surfacing in the future.
Continue watering the young tree—just enough to keep the soil moist. Applying mulch can help retain moisture and prevent weeds from sprouting.
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The dense clusters of white flowers, which resemble orchids, are one of the catalpa tree's most attractive features. | Hans/Pixabay, CC0 |
Catalpa Tree Care
Caring for a catalpa tree involves ensuring it thrives throughout its life, from a young seedling to a mature, majestic specimen. Here are the key aspects of general care to keep your catalpa healthy and flourishing:
Watering
Young Trees: Newly planted catalpas need consistent moisture to establish their roots. Water them deeply once a week during dry spells, especially in their first few years. Avoid letting the soil dry out completely.
Established Trees: Mature catalpas are more drought-tolerant but still benefit from supplemental watering during prolonged dry periods. Ensure the soil is well-draining to prevent waterlogging.
Soil and Fertilization
Soil Requirements: Catalpas are adaptable to various soil types but prefer well-draining soil with a pH range from slightly acidic to neutral (5.5–7). Heavy clay or overly sandy soils should be amended to improve drainage and nutrient content.
Fertilization: Feed young trees with a balanced, slow-release fertilizer in early spring to support their growth. For established trees, occasional fertilization may be beneficial, especially if growth appears stunted. Over-fertilization can lead to excessive foliage growth at the expense of flowering.
Pruning and Training
Young Trees: Prune young catalpas to develop a strong central leader (main vertical trunk) and a well-balanced canopy. Remove any competing leaders and crossing branches to promote a healthy structure.
Mature Trees: Regular pruning of mature trees is generally minimal but may include removing dead, damaged, or diseased branches to maintain the tree’s health and appearance. Prune after the flowering season to avoid cutting off next year’s blossoms.
Mulching
- Benefits: Apply a layer of organic mulch, such as wood chips or bark, around the base of the tree to conserve moisture, regulate soil temperature, and suppress weeds. Keep the mulch 3–6 inches away from the trunk to prevent moisture buildup that could lead to trunk rot.
Winter Care
- Protection: In colder climates, young catalpa trees may benefit from winter protection, such as wrapping the trunk with burlap or insulating the base with mulch. Mature trees are generally hardy and can withstand winter conditions but may benefit from occasional snow removal from the branches to prevent breakage.
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A catalpa sapling supported by a stake. | Carol Norquist/flickr ,CC BY-ND 2.0 |
Quick Facts About Catalpa Trees
Northern Catalpa | Southern Catalpa | Chinese Catalpa | |
|---|---|---|---|
Scientific Name | Catalpa speciosa | Catalpa bignonioides | Catalpa ovata |
Other Common Names | Cigar tree, Catawba Tree, Hardy Catalpa, and Western Catalpa | Cigar Tree, Catawba Tree, and Indian Bean Tree | Yellow Catalpa and Japanese Catalpa |
Height | 40–70 ft | 30–50 ft | 20–30 ft |
Spread | 20–40 ft | 30–40 ft | 20–30 ft |
Leaves | Heart-shaped; 6–10 in long and 6–8 in wide | Heart-shaped; 4–8 in long and 6–8 in wide | Heart-shaped; 10 in long and wide |
Flowers | Trumpet-shaped, white with purple and orange patches inside | Trumpet-shaped, white with purple and orange patches inside | Trumpet-shaped, yellowish-white with purple and orange patches inside |
Fruits | Bean-like pods 8–20 in long | Bean-like pods 8–20 in long | Bean-like pods up to 12 in long |
Lifespan | 50–150 years (depending on conditions) | 50–150 years (depending on conditions) | 50–150 years (depending on conditions) |
USDA Hardiness Zones | Zones 4–8 | Zones 5–9 | Zones 4–8 |
Distinguishing Features | Slightly larger than its southern cousin | Leaves produce a pungent odor when crushed | Smaller than its North American cousins and has a distinct, creamy yellow flower coloration |
The most common Catalpa species at a glance.
Common Pests and Diseases
While catalpa trees are generally hardy and resilient, they can occasionally encounter pest issues and diseases. Proper management is essential to maintaining the health and vigor of your tree. Here’s a detailed look at common pests and diseases that can affect catalpas, along with strategies for managing them.
Pests
Scale Insects and Aphids: Both of these pests feed on sap, weakening the tree and causing potential damage like leaf yellowing or curling. Control them by regularly inspecting your tree and using treatments such as insecticidal soap or neem oil. For aphids, encourage natural predators like ladybugs and lacewings.
Caterpillars: These pests can defoliate your tree if present in large numbers. Hand-picking or applying biological controls like Bacillus thuringiensis (Bt) can be effective methods for managing caterpillar infestations. Note: Catalpa trees naturally attract catalpa sphinx moth caterpillars, which some gardeners welcome as excellent fishing bait. Light defoliation is normal and rarely harms mature trees.
Diseases
Root Rot: Caused by poor soil drainage, root rot leads to wilting and decline in tree health. Prevent it by ensuring your tree is planted in well-draining soil and avoid overwatering. Improve drainage and, in severe cases, consult an arborist about treatment options.
Leaf Spot and Powdery Mildew: Leaf spots and powdery mildew can affect the tree's foliage, causing discoloration and leaf drop. Enhance air circulation around the tree and remove affected leaves. For severe cases, spraying fungicides or natural alternatives such as neem oil or baking soda solution can also help control the disease.
Is the Catalpa Tree Messy?
Despite their beauty and intrigue, catalpa trees are large and messy. For these reasons, be mindful of the area that the roots and branches can cover. Avoid planting catalpas near buildings, fences, sidewalks, and plumbing or electrical lines.
The tree sheds its leaves heavily in the fall, and the seed pods drop throughout fall and winter. After the spring blooming season, spent flowers also create debris. All of this litters sidewalks, driveways, and cars. Regular maintenance is required to keep the mess under control.
Can You Eat the Beans on a Catalpa Tree?
The "beans" have no known nutritional or savory qualities.
Although the fruits resemble bean pods (hence the name "Indian bean tree"), they're not usually eaten.
That being said, they are used in traditional medicine as treatments for ailments ranging from skin infections to conjunctivitis to asthma, although scientific evidence for most of these traditional uses is limited. Source: USDA
Medicinal Uses of Catalpa Tree Parts
Teas and poultices made from the bark and leaves are often used in herbal medicine as laxatives and mild sedatives, and to treat skin wounds and abrasions, infections, snake bites, and even malaria. Some research has explored the potential diuretic properties of Catalpa fruits (pods and seeds), though more studies are needed.
Although the fruits, bark, and leaves are considered safe, according to Andrew Chevallier's The Encyclopedia of Medicinal Plants, the Catalpa roots are highly poisonous. Due to this toxicity risk and the potency of various plant parts, herbal preparations should be handled by or under the guidance of a qualified herbalist or healthcare specialist.
