Crown of thorns can
be shared
Heat-loving plant is
ideal for
June 16, 2005
A friend gave me a plant that had been a
cutting from a plant given to her by a friend. This started my interest in
looking into other varieties of this plant that would bloom year-round but
thrive with our extreme heat and bright sun, with little maintenance.
With its very easy propagation methods, it
could provide a steady supply of plants for gifts,
Master Gardener donated plant sales, as well as garden landscaping. During the
winter this plant loses some leaves, but the spring season renews the stalks
with dark green foliage. Local nurseries have several varieties of this plant
called crown of thorns, which has become a favorite of mine.
After some 30 years of breeding selection by
various professional and private enthusiasts, these plants are an exotic
addition to any nursery's plant portfolio. They are a good selection for
Southern gardens as they are incredibly heat tolerant. In fact, they are
capable of thriving when temperatures are above 90 degrees. They will tolerate
full sun and salt spray thus making for good container plants in our coastal
climate flowering nearly all year.
They will, however, freeze. Crown of thorns
can handle temperatures down to 30 degrees; too cool temperatures cause the
stems to be mushy.
These plant characteristics are reason enough
for my choosing the crown of thorns for container plants in my personal garden;
however, I find the history of the plant and how it has been shared through
time equally as compelling. The Internet proved to be a good source for
research and identification of the wide varieties of this plant.
According to an article by Dr. T. Omrello of
Where does this unfamiliar nomenclature come
from? Euphorbia was the Greek physician of King Juba II of
The crown of thorns is a woody, spiny,
climbing, and sometimes vining, succulent shrub with
shoots reaching a height of up to 6 feet. Leaves are found primarily on young
growth. The plant flowers nearly all year; the actual flowers are small but the
brightly colored modified leaves (bracts) found just beneath the flowers are
what make the plant quite attractive.
A sticky white sap (latex) exudes from a cut
to the plant and may produce a severe dermatitis on susceptible individuals and
should not be ingested. The article referenced above goes on to say that the
latex of some species has been used for arrow poisons and to stupefy fish for
capture.
Euphorbias are not planted near stocked pools since the exudates
from broken roots can be fatal to fish. Cats and rabbits might be susceptible
to these plants; deer and cattle will not eat them. Despite its poisonous
properties, the latex has been used for medicinal purposes in the past.
The original forms were mostly bright red in
color; leaves were sparse and thorns were prominent. The newer cultivars have
reduced thorns (actually more like ridges on the stem) and have large
attractive leaves, existing in a range of colors from red, orange, salmon,
pink, yellow and a creamy white, including bicolor bracts. They are relatives
of poinsettias.
Newer releases from
Even if all conditions are right, crown of
thorns will sometimes flower poorly or not at all, especially in urban
locations where perhaps lights on the plants at night (street or security) can
disrupt their flowering cycle.
This plant family can be divided into two
groups - the common, older types and the recently developed Thai hybrids. More
than 2,000 varieties have been developed. The older types were developed by Humel in 1960 with the "giant crown of thorn"
being most common. A newer Thai version is the compact-dwarf "Short and
Sweet," which is excellent for use as ground cover, as well as the
"Mini Bell."
Many varieties have increasing availability
where some are sold as bare root. It takes 12 to 14 days for the bare roots to
form fresh roots.
A few pests occur occasionally with crown of
thorns and include scale insects, mealybugs, spider
mites and thrips. Ants do not like the sticky
substance on the stems. Disease is more common, and usually includes too much
moisture with bacterial and fungal leaf spots, fusarium
and rhizoctonia stem and root rots as well as
botrytis flower blight. Yellow or dead foliage should be removed. The disease
is more prone to develop with tools and equipment not being clean. A modest
amount of rain is well tolerated but the dried flowers and leaves should be
cleaned before periods of prolonged wetness. Watering at the bottom of stems is
better than overhead due to water collecting in the flower heads.
The obvious pruning problem for crown of
thorns is the toxic milky sap excretion, which should be kept out of eyes. A
significant benefit to pruning is that cuttings can be potted and you will have
other plants. Crown of thorns responds well to repotting, and, in fact, it is
one of the few plants that can be repotted lower than the original soil level
to enable additional cuttings to root.
A cutting should be at least 4 inches long
(and longer if possible) to root properly and should be kept in a shaded area
until rooted. A clean sharp knife should be used to take cuttings; use only
inexpensive knives as the sap can ruin cutting edges. The cuttings can be
allowed to dry for 24 hours before planting; rooting hormone powders could help
the rooting progress. A dropped leaf may be successful in rooting or seeds
taken from the flower will produce plants when care is given.
Seed propagation is usually done for
developing cultivars with two different varieties being used. It will take five
to eight months to flower with seed propagation.
Try this colorful, sun- and heat-loving plant
in your garden landscape. I am certainly grateful for the friend who shared my
first cutting from the friend who first shared this plant with her. Its many
attributes could be the reason for the on-going nature of this beauty that has
been shared for thousands of years.