Kiril Donov writes about amazing hardy Trachy's
in Bulgaria, and speculates about a dark reason for their extraordinary
resistance to cold.
by Kiril Donov, Plovdiv, Bulgaria
Chamaerops No.38, Spring Edition 2000
Bulgaria is located in southeast Europe, north of
Greece. I believe we have here the hardiest palm trees in the world.
There are 4 trees (Trachycarpus fortunei) in the historical museums
yard in Plovdiv. Their age is about 50 years. They produce seeds
every year, and occasionally something very funny happens - they
change their sex in different years. The tallest palm, a male plant,
has twice changed its sex and produced seeds, but all of the seeds
have been lifeless. These 4 plants are the first palms living outdoors
in Bulgaria. From their seeds we have our population of Trachycarpus,
surviving with no problems at temperatures below -28C (-18,4F).
The absolute minimum temperature in this area is -31,5C (-24,7F).
Unfortunately, the people in the museum are not very friendly; if
anyone visits the museum and wants to see the palms, he will meet
a stone wall. They probably hate the palms because more people visit
them than the museum! One version of how the palms came to be there
is that a man who used to work there planted them. However, when
I visited the museum again in the beginning of November and talked
to the person in charge, he said that he planted the palms in 1973.
When I visited the museum for the first time in 1989 he had said
that nobody knows when they were planted, and that when the Russians
had come in1944 the palms were already there. So, we really do not
know what is the truth. For the last10 years he has been cutting
the flowers and the palms havent produced seeds, but last
year I saw about 3000 seeds hanging on the female tree and arranged
to buy all of them.
I was very surprised to see that each of the four
palms grew more than1m trunk last summer. The highest palm is 7m
tall and has been there for 50 years. A meter of growth is really
amazing! How is this possible? Heres my theory. The city of
Plovdiv was established by trackians some 4-5 thousands years ago,
before the Greek and Rome empires. It is located in Trackian lowland
at150 m above the sea level. The nearest mountain is15-km away (Rhodopa
Mountain). But in Plovdiv there were 7 hills, with about 350-m height.
The people have already destroyed 3 of them, but the other 4 still
remain like mountains in the lowland. All buildings were located
on the hills. The historical museum is on one of those hills, on
a huge slope. There is a big support stone wall, 3m in height, and
a small place with even surface. There live the palms. The climate
in Plovdiv is very dry in summer and the palms have never been fertilized
nor watered, or so said the staff there. But last summer they were
provided with some water, as the whole year had a lot of rain and
snow. Suddenly there were weeds like trees on the field. So, it
is possible that the extremely slow growth of the palms is caused
mainly by the drought, as any signs of cold damage are not often
seen. The soil available to them is very limited, maybe no more
than a big pot. It dries out very quickly when temperatures reach
I have had the same experience with my own palms.
During the first years I didnt provide any water or fertilizers
in summer and they had very slow growth with small leaves. The last
2 years I made irrigation systems and they grew like crazy. Four
years ago I gave a friend of mine 2 small palms, about 30cm tall,
3 years old. He planted them outside in late autumn. They survived
with no problems at all. Today they have about 60cm of trunk and
leaves probably bigger than the parent plantsin only 4 seasons!
Those 2 palms came from seeds from the Four palms in Plovdiv. In
those 4 winters they didnt have any leaf damage, even when
the temperature was -22C (-7,6F). We just didnt have lower
temperatures to test them. Last thing ... many people say that palms
should not be replanted in the ground any deeper or higher than
they were found. Id like to tell you that I always do this.
If the soil is not very heavy, I always plant the young palms 10-30cm
deeper. In one year the plants grow over the surface again. Ive
found this is the best protection, and Im doing it this year
in my new palm nursery too. My friend planted his 2 palms more than
40 cm deeper.
Bulgaria, with an area of 42,855 square miles (110,994
square kilometers), is a little smaller than Greece. The country
is divided into two parts by the east - west chain of the Balkan
Mountains. The climate of Bulgaria is continental, with warm summers
and cold winters. In the southern portion of the country, which
is tempered by Mediterranean influences, and along Bulgarias
Black Sea coast the winters are comparatively mild. The climate
is on the whole favorable for agriculture, but it is too cold for
the growing of citrus trees. The summers in Bulgaria are very hot
- daytime temperature +35 to +40C (95-105F) sometimes +45C (113F).
The spring is quite short (1 month) and autumn quite mild. Our winters
usually bring frosts with no more than -7 to -8C (16-20F), but it
is normal for temperatures to drop down to -20 to -25C (-4 to -13F)
at least once. Temperatures go down below -25C (13F) at least once
per three winters, and once per 5-10 winters down to -28C (-18,4F)
and below, although it is very unusual for these heavy frosts to
last more than a week. Temperatures have been observed to drop down
to -28C (-18,4F) not less than ten times during the last 40 years.
My own palms once survived very successfully at -28C (-20F) and
several times at temperatures down to - 25C (-13F). Generally, however,
our winters are really mild: +5 to +15C (41-59F); but, with the
above mentioned exceptions, we go directly into Europes hardiness
zone 6 and below.
It is not only my opinion that in Bulgaria we have
developed a variety of Trachycarpus fortunei which could survive
at lower temperatures than the original plants. All of the palms
grown today in Bulgaria are produced from seeds that were produced
by the palms in the historical museums yard in Plovdiv. I
wanted to have the same success with my Washingtonias, even with
my Chamaerops humilis, but all of them died during the winter of
1998/99 at -22C (-7,6F). This year I am trying to grow Sabal minor,
Jubaea chilensis, Butia capitata, Phoenix canariensis, Chamaerops
humilis and Washingtonia filifera outdoors with some heating. The
winter frost in Bulgaria is dry. Usually there is no need to use
any protection, or else the results could be worse. The only protection
I use for my palms is from the wind. I put hay or straw around the
trunk and that is all. Of course the protection is not applied to
Trachycarpus fortunei, but to any other palm. One-year seedlings
could be used for planting outdoors, or even seeds, but when using
3 year or older plants, results will be much better and faster.
We suppose that there is some genetic change, because 10% of the
seedlings are not able to survive at very low temperatures (D.Kozarov,
Ph.D. work in 1996). (Mr. Kozarov wrote in his Ph.D. work about
Trachycarpus fortunei in Bulgaria that his palms have survived -29C
(-20,2F), recorded at the palms location.) Also, different plants
feel frost differently. Plants that are planted at the same age,
on the same day, and in the same conditions are not developing equally.
I am so sure about palm hardiness, that last year
I decided to create a hardy palm nursery. Its a kind of revolution
for Bulgaria to grow palms in the open ground, but Im growing
all my palms outside after their second year of age. I grow the
palms exactly like any other trees here. My nursery is located in
the area of Plovdiv (4-5 km away from the city) in open field, with
strong west winds and each year minimum temperatures of -20C (-4F).
The absolute minimum temperature is -31,5C (-24,7F) recorded about
50 years ago. Average precipitation is 600 mm per year.
Two summers ago we had many strange things here. Many
plants died at once with no reason. Other plants grew like crazy,
like never before. There was a war in Kossovo, 500 km away from
here. I read in newspapers that NATO used bombs containing uranium.
I dont know if the bombs caused something (our government
said nothing), but my Grandmother lost the tomatoes in her garden
for first time in her life (75yrs.old). I just remember that the
same happened when the nuclear reactor in Chernobyl exploded. But
then the tomatoes were giants.
You know, we had very close relations with the Russians,
also with their science. We dont know if our palms are the
result of their science and therefore if even more incredibly hardy
palms could be found there. I know that before 1956 it was an obligation
for the scientists to develop subtropical plants that are able to
live in our climates! In result there are many cold hardy plant
species available now. In Bulgaria they tried to grow even Citrus
and Date palms too, but soon gave up. The 4 original palms I mentioned
could have been brought from Russia. Of course they could be from
anywhere else. They also could have been developed here influenced
by our local conditions. We do not know yet. But I have decided
to realize my dream to see palms everywhere in Bulgaria.
10-07-20 - 19:37GMT
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