The catalpa tree encompasses 10 species, of which two are native to the U.S. It is a member of the family Bignoniaceae. The northern catalpa and southern catalpa are both deciduous and can reach a height of 100 feet at maturity. In late spring, the tree produces showy white flowers with throats blotched and striped in purples and orange. Catalpa trees are quite hardy and their seeds easy to propagate. They make good shade or specimen trees and are a habitat for birds and small wildlife.
Wait until late fall or early spring for the seeds to turn brown and become fully ripe, before planting. Northern catalpa seeds produced in early spring are more viable than those produced and planted in fall.
Pick the seeds once they are ripe and open the seedpod. Separate the seeds by placing them into a plastic bag and shaking them.
Fill a one-quart planting container with a lightweight potting mix that is rich in organic material. Use a mixture that contains peat moss or compost. Be sure the planting container has drain holes in the bottom so it will not retain water. Water the container before you plant the seed in it. This will create moisture in the soil and firm it up before placing the seed into it.
Place the catalpa seed into the center of the container on top of the soil. Sprinkle a light covering of potting mix over the seed, to cover it slightly. Do not plant the catalpa seed too deep or it will not germinate.
Water the container again. Keep the container moist until the seed germinates. Do not keep the soil flooded or the catalpa seed will rot and not sprout. The seed should germinate in approximately two weeks.
Situate the container in an area that receives either partial or filtered sunlight throughout the day. Catalpa trees prefer to grow in partial shade conditions once planted outdoors in the ground.