Birch - Betula sp.
General information: Birches are pioneer trees, meaning that
they grow in open fields, and grow rather quickly at that. They are thus
short-lived, usually dying back between age 60-100, and they will not grow
in the shade. Birches have peeling bark and pendulous catkins. Many
birches have a distinctive white bark which is colored by a pigment
called, appropriately enough, betulin. A few birches, such as the yellow
birch and sweet birch will grow in the south, but most birches prefer
Birches are much loved for bonsai because of their
elegant beauty, but they do not take easily to pot culture. Their short
lives are also seen as a disadvantage; however, some birches will live as
long as 300 years.
Lighting: Birches like
a lot of light, although some shade is advisable in the hottest areas or
are very cold hardy, but may need protection from cold winds to prevent
Watering: Birches like
frequent watering, although they should not be left to stand in moisture.
Reduce water in winter, but never let the soil dry completely.
Feeding: Wait one month
after leaves open, then feed every two weeks till the end of
Pruning and wiring: Trim back shoots to the first pair of leaves throughout growth.
It is wise to make large pruning cuts late in the season, as birches
"bleed" profusely when the sap begins to run.
Propagation: Propagation methods vary depending on the species. Betula
pendula grows most reliably from seed; cuttings root only with difficulty.
Cultivars of this species need special measures to root sucessfully.Other species, such as Betula nana, are reputed to
root easily from cuttings.
younger than age 10 will need repotting every two-three years. Older trees
need repotting as necessary. Repot in spring, before bud burst, using
free-draininig soil mix. The bark may take up to ten years to turn white
in pot culture, but this can be expedited by a few years in a growing bed.
Care should be taken to protect the bark when wiring. The tree may sucker
from the roots; these should be removed quickly to keep from sapping the
vigor of the main trunk.
Pests and diseases: Pests and assorted obstacles: Bronze birch boarer, birch leaf miner.
Proper watering and a good fertilization in early spring have been
reported to help stave off miner attacks. B. pendula 'Trost's Dwarf' must
be shipped only when dormant or the tree may become sick or die. This may
be due to abrupt change in lighting, climate etc. and may be a
consideration if the tree is to be transported any great distance. Birch
may "bleed" to death if pruned out of season. It has been my experience
that birch can be sickly in pot culture and shocks easily when root
Some species suitable for bonsai:
- Betula alleghaniensis: yellow birch - A native of
northeastern America, reaching as far south as Georgia, the yellow birch
can reach up to 70 feet tall. Its bark is a pale gray- brown, and peels
off in rolls. It has larger leaves than most birch.
- Betula lenta: black birch, sweet birch, cherry
birch - In nature, grows in moist, cool woods east of Ohio, further
south than most birches, ranging from Ontario to Alabama. Its bark is
gray-black or reddish-brown. Its oval leaves turn brilliantly gold in
the fall, and it can grow up to 70 feet. Used in the manufacture of oil
of wintergreen, this tree is very nice smelling.
- Betula maximowicziana: monarch birch.
- Betula nana: dwarf birch, Arctic birch - The dwarf
birch is especially recommended for bonsai because of its tiny leaves,
which show a fine red-gold autumn color. It also has a copper colored
bark. It is native to the far north up to the Artic circle, and can
survive on only three months of sunlight a year!
- Betula papyrifera: canoe birch, paper birch, white
birch - Has white bark and oval leaves. Native to the colder parts of
- Betula papyrifera: paper birch, white birch, canoe
birch: The shiny white bark of this birch was used by Native Americans
to build canoes, hence the name. It grows in northern climates, zones
2-6. The leaves are heart-shaped, from 2-4 inches long, yellowing in
autumn. It can grow up to 90 feet, but usually not more than 70, and
takes on an oval habit. It is susceptible to bronze birch boarer.
- Betula pendula: the Eurpoean white birch, silver
birch - This tree has silver-white bark with black, diamond-shaped
markings. Its heart shaped leaves turn gold in the autumn. A cold
climate tree native to Europe, it has been planted as far south as
Maryland, but prefers zones 3-5. It can grow to 60 feet, and the
branches tend to weep. Many trees in the north-east have been devastated
by the bronze birch boarer.
- Betula pendula 'Fastigata'
- Betula pendula 'Lanciniata'
- Betula pendula 'Purpurea'
- Betula pendula 'Trost's Dwarf': This dwarf only
grows 3-4 feet, and is highly sought after for bonsai. It has leaves
unique for birch, which resemble those of a threadleaf maple. The leaves
are about 2 inches and the tree will grow to 4 ft. tall. It is more
light tolerant than most birches.
- Betula pendula 'Youngii': The small leaves, very
white bark and excellent ramification of this tree make it very
desirable for bonsai. It weeps naturally, without wiring, and can easily
be twisted into serpentine shapes.
- Betula platyphylla Japonica: Japanese white
- Betula populifolia: gray birch - The gray birch is
identifiable by its leaves, long-tailed and pointed, which have Pale
yellow autumn color. The bark is white with black markings where
branches have arisen. It is native to Northern America and
- Betula pubescens: smooth-bark birch
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