Propagation of the Northern Catalpa Tree: Catalpa speciosa
Christopher Besemann: March 2003: NDSU PLSci - Plant Propegation
1.
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
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 [
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.
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 [
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
Ohio Department of Natural Resources
and The Ohio State University Department of Horticulture and Crop Science,
2002