BETULA PAPYRIFERA – BIRCH, PAPER
The tree is best adapted to moist, cool sites with deep, loose soil with irrigation provided in times of drought. Protect from all day sun by locating the tree so it is shaded for part of the afternoon in the summer and irrigate in the dry summer weather. Plants perform best on north facing slopes in the Rocky Mountain region. This tree provides inescapably beautiful bark. Mulch the soil under the canopy out to the edge of the dripline to minimize competition with turf. This will allow roots to become well established. Few urban sites fit these requirements.
Birches in containers tolerate moderately-high soil salt solutions up to about 6 mmhos/cm according to the saturated media extract method. Birch pollen causes significant allergy in some people but pollen is produced for only a short period and in small amounts.
Watch for pests if grown on other than optimum sites. Quick action is essential if pests are noticed. It recovers best from spring transplanting. Pruning is best performed in the dormant season, or late summer, not in the spring or early summer. Trees are very susceptible to damage from ice loads.
Trees rarely live more than 140 years in the forest, typically shorter in the landscape. Animals of all kinds consume the foliage and twigs. This is the state tree of New Hampshire.
Paper Birch is now tapped for its sap which is made into a sweet syrup. Each tree produces about 100 gallons of sap each spring during a 4 to 5 week period. It takes about 26 gallons of sap to produce one quart of syrup. That compares to about 10 gallons of sap from the Sugar Maple tree to produce one quart of maple syrup.
Wood specific gravity averages about 0.55 g/cc. Wood is considered diffuse porous meaning that there is little difference in size of pores between spring and summer wood. Birches are considered poor compartmentalizers of decay. This means decay can develop and spread quickly following mechanical injury from construction activities near the tree, vandalism, storm damage, or improper pruning cuts. Seeds are attractive to birds including goldfinch and red poll.
Several cultivars are available including ‘Cenci’ Renaissance CompactTM(zone 3, slow grower, upright compact habit, good exfoliating bark); ‘Oenci’ Renaissance OasisTM (zone 3, resists bronze birch borer, moderate growth rate, broad dense pyramidal habit, reddish exfoliating bark); ‘Renci’ Renaissance ReflectionTM (zone 3, resists bronze birch borer, fast grower, semi-exfoliating bark); ‘Uenci’ Renaissance UprightTM (zone 3, narrow upright habit, fast growing, good resistance to bronze birch borer)