Tony Dickerson answers your questions
QIs my damaged Himalayan birch coming back to life? Julie Gertch, Goole, East Yorkshire
AIn common with other coloured-stemmed birches, Betula utilis jacquemontii ‘Silver Shadow’ is propagated by either cuttings or, more commonly, by grafting onto a rootstock of silver birch in late winter. If your damaged tree was a cutting, the regrowth from the lower trunk will be your named selection ‘Silver Shadow’. If, however, your tree was grafted and the regrowth is coming from very low down, it could be from the silver birch rootstock.
In either case, birches need to grow with a straight trunk to look attractive so if the current growth is poor, cut it back hard now and next summer tie the new shoot into a bamboo cane or, if a number of new shoots form, select three and grow it on as a multistemmed tree.
The brilliant white-stemmed Himalayan birch of gardens are selections of
B. utilis and its variant B. jacquemontii. ja This species is found throughout the Himalayas from Afghanistan to South West China. Interestingly, the species tends to be whitestemmed in western areas, but east into Nepal and China the predominant bark colour is orange-brown to dark copperybrown. B. utilis selections, such as ‘Park Wood’ and ‘Wakehurst Place Chocolate’, are even darker with glossy, chocolate-coloured bark. B. utilis jacquemontii ‘Silver Shadow’ is one of the most attractive white-stemmed birch with dazzling trunks. It has large, dark-green leaves with attractive gold autumn colour and good bark colour starts to develop between five and seven years. In common with other Himalayan birches, it grows quite quickly for the first 10-15 years to make a good garden tree, but growth then slows dramatically, which is a really useful characteristic.
Ultimately, these trees grow to 12-15m (40-50ft), which can be a little too large for suburban gardens. However, multi-stemmed trees often make only two-thirds of the mature height, which is a useful characteristic that also looks good in smaller gardens.