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Carpinus - Growing Guide
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Carpinus - Growing Guide

Hornbeam

Hornbeams are a genus of trees to which quite a number of new species have been added in the last 20 or so years from new wild collections in China, Taiwan and Vietnam. We have been growing and trying out several of these new Carpinus species at Burncoose and Caerhays and these are now starting to find their way into our catalogue.

For years hornbeams meant just (to us) the common or native Carpinus betulus and its improved forms which we have offered; such as Carpinus betulus ‘Fastigiata’. Then came new grafted plants of the exceptional Carpinus fangiana with its enormous ‘hop-like’ flowers in profusion.

C. betulus 'Fastigata'

C. betulus 'Purpurea'

Now we are now growing C. fargesiana, C. polyneura, and C. rankanensis (which grows so splendidly at Westonbirt Arboretum) and several other species which have different tree shapes and forms, attractive leaves and, in some but not all cases, startling autumn colour.

Carpinus polyneura

Carpinus rankanensis - young tree

Carpinus rankanensis

C. rankanensis - 2nd younger one

We now have a few plants available of the (with us) evergreen Carpinus kawakamii from Taiwan. At Caerhays this is now, after 20 years, a spreading, upright tree with attractive new growth (especially the secondary new growth in the autumn) and has happily survived the March 2018 ‘Beast from the East’ without losing the majority of its (evergreen) leaves. The potential this tree has in street planting, in communal spaces, and in British gardens generally, has excited several UK nurserymen but it will take much time to propagate and grow enough plants of this new species for it to move on fully into the public domain.

All Carpinus species are proving to be totally hardy and will grow as freestanding or woodland trees in fairly well drained soil. Carpinus betulus can (with a lot of effort) be grown as a hedge like beech or, as at RHS Garden Rosemoor, as a well-manicured and twice a year trimmed formal hedge of 18-20ft in height. C. betulus seeds (and other species) can be sown in the autumn in a seedbed. Carpinus can also be propagated from new shoot cuttings that have hardened off but winter casualties (as with many deciduous trees) are normal. Seed are easier.

Carpinus japonica has proved to be a beautiful tree at Caerhays with corrugated leaves and prominent catkins. You can see pictures of our youngish plants below this article.

Carpinus japonica - young tree

Carpinus japonica

Carpinus turczaninowii is another newish species which grows well here. It has a shrubby habit initially and then develops into a decent tree with exceptional autumn colour (even in windy Cornwall) which shows great promise for its future in UK gardens even if we all still struggle to pronounce the name.