Birches are pioneer timber, that means that they develop in open fields, and develop moderately shortly at that. They’re thus short-lived, often dying again between age 60-100, and they won’t develop within the shade. Birches have peeling bark and pendulous catkins. Many birches have a particular white bark which is coloured by a pigment referred to as, appropriately sufficient, betulin. Just a few birches, such because the yellow birch and candy birch will develop within the south, however most birches favor colder climates.
Birches are a lot beloved for bonsai due to their elegant magnificence, however they don’t take simply to pot tradition. Their quick lives are additionally seen as an obstacle; nonetheless, some birches will reside so long as 300 years.
Birches like loads of gentle, though some shade is advisable within the hottest areas or in midsummer.
Birches are very chilly hardy, however might have safety from chilly winds to forestall twig die-back.
Birches like frequent watering, though they shouldn’t be left to face in moisture. Cut back water in winter, however by no means let the soil dry utterly.
Wait one month after leaves open, then feed each two weeks until the top of summer time.
Pruning and wiring:
Trim again shoots to the primary pair of leaves all through progress. It’s sensible to make giant pruning cuts late within the season, as birches “bleed” profusely when the sap begins to run.
Propagation strategies differ relying on the species. Betula pendula grows most reliably from seed; cuttings root solely with problem. Cultivars of this species want particular measures to root efficiently. Some strategies from Brent Walston of the Web Bonsai Membership that can work for B. pendula ‘Trost’s Dwarf’ and ‘Youngii’:
Rising them from cuttings is feasible, however troublesome. As with all birches the timing is essential. One of the best time is get them simply earlier than finish bud set in mid summer time. It will differ from area to area, in Northern California, the best time appears to be early July. For those who have by no means observed, terminal buds develop all through the rising season solely to open into new leaves till mid to late season when as a substitute of increasing the bud hardens in preparation for dormancy and opening the next spring. That is referred to as bud set. Earlier than bud set the buds are inexperienced, however the set buds flip brownish as they harden. Birches root greatest simply earlier than set, so search for intact buds that you just suppose are usually not going to open and take the semi hardwood cuttings whereas the buds are nonetheless brilliant inexperienced. Use hormex Eight or IBA 0.8%. Maintain the cuttings cool and moist, in the event that they root the buds will break and you’ll get some new progress earlier than the top of the season. That is almost important for overwintering them.
Different species, reminiscent of Betula nana, are reputed to root simply from cuttings.
Birches youthful than age 10 will want repotting each two-three years. Older timber want repotting as obligatory. Repot in spring, earlier than bud burst, utilizing free-draining soil combine. The bark could take as much as ten years to show white in pot tradition, however this may be expedited by a number of years in a rising mattress. Care needs to be taken to guard the bark when wiring. The tree could sucker from the roots; these needs to be eliminated shortly to maintain from sapping the vigour of the primary trunk.
Pests and illnesses:
Pests and diverse obstacles: Bronze birch borer, birch leaf miner. Correct watering and a great fertilization in early spring have been reported to assist stave off miner assaults. B. pendula ‘Trost’s Dwarf’ should be shipped solely when dormant or the tree could grow to be sick or die. This can be because of abrupt change in lighting, local weather and so on. and could also be a consideration if the tree is to be transported any nice distance. Birch could “bleed” to loss of life if pruned out of season. It has been my expertise that birch might be sickly in pot tradition and shocks simply when root pruned.
Some species appropriate for bonsai:
Betula alleghaniensis: yellow birch – A local of northeastern America, reaching as far south as Georgia, the yellow birch can attain as much as 70 ft tall. Its bark is a pale gray- brown, and peels off in rolls. It has bigger leaves than most birch.
Betula lenta: black birch, candy birch, cherry birch – In nature, grows in moist, cool woods east of Ohio, additional south than most birches, starting from Ontario to Alabama. Its bark is gray-black or reddish- brown. Its oval leaves flip brilliantly gold within the fall, and it could develop as much as 70 ft. Used within the manufacture of oil of wintergreen, this tree may be very good smelling.
Betula maximowicziana: monarch birch.
Betula nana: dwarf birch, Arctic birch – The dwarf birch is particularly beneficial for bonsai due to its tiny leaves, which present a nice red-gold autumn coloration. It additionally has a copper coloured bark. It’s native to the far north as much as the Arctic circle, and may survive on solely three months of daylight a yr!
Betula papyrifera: paper birch, white birch, canoe birch: The shiny white bark of this birch was utilized by Native People to construct canoes, therefore the identify. It grows in northern climates, zones 2-6. The leaves are heart-shaped, from 2-Four inches lengthy, yellowing in autumn. It could develop as much as 90 ft, however often no more than 70, and takes on an oval behavior. It’s vulnerable to bronze birch borer.
Betula pendula: the European white birch, silver birch – This tree has silver-white bark with black, diamond-shaped markings. Its coronary heart formed leaves flip gold within the autumn. A chilly local weather tree native to Europe, it has been planted as far south as Maryland, however prefers zones 3-5. It could develop to 60 ft, and the branches are inclined to weep. Many timber within the north-east have been devastated by the bronze birch borer.
Betula pendula ‘Fastigata’
Betula pendula ‘Lanciniata’
Betula pendula ‘Purpurea’
Betula pendula ‘Trost’s Dwarf’: This dwarf solely grows 3-Four ft, and is extremely wanted for bonsai. It has leaves distinctive for birch, which resemble these of a threadleaf maple. The leaves are about 2 inches and the tree will develop to Four ft. tall. It’s extra gentle tolerant than most birches.
Betula pendula ‘Youngii’: The small leaves, very white bark and glorious ramification of this tree make it very fascinating for bonsai. It weeps naturally, with out wiring, and may simply be twisted into serpentine shapes.
Betula platyphylla Japonica: Japanese white birch
Betula populifolia: grey birch – The grey birch is identifiable by its leaves, long-tailed and pointed, which have Pale yellow autumn coloration. The bark is white with black markings the place branches have arisen. It’s native to Northern America.
Betula pubescens: smooth-bark birch
Compiled by Sabrina Caine