Our september plant of the month is Ostrya carpinifolia, common name European Hop Hornbeam, a deciduous small to medium sized tree which can add an architectural element to a contemporary landscaping project. It is slow growing and can thrive in most conditions in a garden. It is able to survive the dry soils of Cambridge once established and endure the coldest British winter down to –20. The leaves are an attractive dark green, with deep veining and double toothing around the margins, during autumn this plant’s leaves turn a beautiful yellow, drawing the eye in any contemporary garden design.
The flowers of this tree are striking when first emerging in summer, resembling cream with a tinge of green, hops. These fade over the season to a warm brown, retaining their interesting shape. This specimen also produces catkins that are slightly longer than the flowers, these form in autumn. When at full height this tree is a striking addition to modern gardens, giving good value for money in terms of seasonal interest, a good one for designers looking for something a bit unusual.
Photo credit: Louise Singfield
When planting this Ostrya, be sure to choose a good healthy plant, choose to do it in October to April, first mark a 1.5m circle where you plan to plant your tree and take off the turf in this area and remove it. Within the circle dig a square pit to the depth of your tree's root ball, hitting the edges of the circle. Don’t add any compost or fertiliser to the hole as this will create slumping, moisture issues and encourage the roots to circle round themselves, especially in container grown trees, ensure you rough up the roots a bit before planting to encourage spreading.
One of the most important things to remember when planting is to not plant too deep, make sure the soil does not come above the nursery line, some species are very sensitive to this, you can use a straight edge across the pit to ensure the levels are right. When backfilling, do so in layers, firming them down with the heel of your foot. The final step is to apply mulch to a depth of 10cm and water, when mulching, graduate the mulch to nothing as you get to the tree's trunk to avoid stem girdling roots. Continue watering the tree over its first year or two to give your tree the best chance in your new design.