Propagation of the Northern Catalpa Tree:  Catalpa speciosa

Christopher Besemann: March 2003: NDSU PLSci - Plant Propegation


The Catalpa tree is an interesting tree that has had its time of popularity in the past.  Although it is often criticized as a poor specimen today, it can still be a great tree if given the proper place.  Also of note are possibilities of trying to manipulate it through breeding or other means to maximize the good traits of tree while minimizing the bad.  Some of these techniques will be pointed out throughout this report.    

Past landscapers have used this tree for its stately form.  As mentioned earlier, many feel that the tree does not maintain its leaves well throughout the season [Missouri].  In the fall, leaves turn a yellow color which is not as striking as other choices.  Throughout the year, the large leaves may be damaged by weather.  The unusual aesthetic impact of the large seed pods may outweigh the maintenance they cause in some consumers minds.  Perhaps there is hope if a variety can be designed to hold the fruit longer, or create female only trees.  Flowers of this tree are very nice while they last.  In the past they have been grown for use in fence posts as a economic value.

  For focus in this paper we will look at the hardier variety of the species, Catalpa speciosa.  It is also known as the Northern Catalpa, Hardy Catalpa, Western Catalpa, Catawba, or Cigar tree.  Hardiness is a characteristic that growers in northern United States will appreciate. 

The family is Bignoniaceae.  Other members of this family are Trumpet Vine, Royal Paulownia, and other species of Catalpa, all of which are known for their showy flowers [ Ohio ]. Typically grown in the Midwestern US, this variety is hardy to zone 4.  This means that is can be grown in North Dakota , and with caution and correct care can even be grown into zone 3.

Catalpa trees have tropical background and need full sun to partial shade.  It is ideal for low lying areas that are moist, as it prefers medium to wet soil conditions.  Seasonal flooding is not a problem for this species.  It can also tolerate dry conditions and thus is versatile for location.  Ideal soil is rich but, as stated, any soil will work.

There are very few problems associated with Catalpa trees.  Leaf spotting and damage from insects such as the catalpa sphinx moth can cause substantial damage on occasion.  However, from a domestic standpoint, the main cost is in season maintenance associated with pod clean-up.

2.  Characteristics

What make a Catalpa tree so special?  Looking at some of the identifying characteristics should answer that question.  Stately in ideal form, this deciduous tree has an open, oval shaped habit.  The leaves are large and heart shaped from 6 to 8 inches wide.  Flowers are white with yellow and purple inner spots, appearing much like foxgloves.  These are perfect flowers, so if one wishes to avoid fruiting, new designed varieties would need to be made.  Many blossoms form starting in early summer (May to June).  Flowering does not begin until a tree is about 15 years old.  Probably one of the major defining characteristics are the long (20 inches), brown seed pods.  Trees can attain heights of 35 to 40 feet.  Care should be taken when selecting this tree, as its size and large shade zone can cause problems in a small area.    

  3.  Seed Propagation

Large ‘bean’ pods are a distinguishing characteristic of the Catalpa tree.  Seeds can be harvested and used for propagation.  Large crops of pods appear every 2 to 3 years.  As is turns out, this is the most common means of propagation for this tree.

Late winter is the best time to collect seeds.  Although, it should be noted that in the fall, the pods will split and release the winged seeds to the ground.  Leaving them until after break gives the them time to cure as the Catalpa is dehiscent.  Spring time, when the temperature is 70-85 degrees Fahrenheit, is the best time to plant the seeds.  Alternatives are using cold frames or greenhouse planting.  If all goes well, the seeds should germinate in two weeks.

4.  Cutting

Catalpa trees can be propagated from cuttings taken during the summer.  Semi-hard and softwood cuttings can be taken from non-flowering shoots.  Studies have shown that the best cuttings come from first year cuttings.  Expected rooting percentages go from almost 100% for first year, to 77% in third year [ Gardner ].

5.  Potting

Plants obtained from other sources may begin in pots.  Planting should occur in the spring or early fall.  Keeping the tree in a sheltered area will help to protect the large leaves from damage.  Again, these trees are tolerant to dry conditions as well as moist conditions.  Pruning can be kept to a minimum.  Training a younger tree to a straight central leader will help produce the classical shape and keep weak branches to a minimum.  During the course of its life, a Catalpa will require light pruning of weakened branches.

6.  Grafting

Catalpas can also be propagated by grafting.  This is a recommended procedure if you have a specialty variety and do not want to risk cross-pollination from related but different varieties.  By grafting, you can also preserve some unique characteristics between varieties.  For example, one resource cites the availability of “Mop Top Trees”.  These trees are smaller trees with topiary like bushy tops.  In the case of a Catalpa “Mop Top”, dwarf Catalpa is grafted onto a seedling say northern Catalpa.  As a landscaping plant, the small space requirements and low maintenance make it a nice alternative to a “true” variety.

7.  Resources

Gardner , F.E. 1930. The relationship between tree age and the rooting of cuttings. Proc. Amer. Soc. Hort. Sci.26:101-104.

Missouri Botanical Garden , February 2001, Last Updated October 2002

Ohio Department of Natural Resources and The Ohio State University Department of Horticulture and Crop Science, 2002

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