Pruning

In the spring, allow the new shoots of Hornbeam and Beech species to elongate and fully harden off.  Hardening off is indicated by the change in texture of the leaves from velvety to glossy and the change in color from light and florescent to darker and duller.  In the northern hemisphere, this usually occurs sometime in the month of May.  By that time, the new shoots should have elongated to 6-8 leaves, at which point you can cut each shoot back to 2 or 3 leaves depending on the situation.

After cutting the shoots in May, a new set of shoots will emerge and elongate.  Allow these to grow unimpeded for 6-8 weeks and again cut them back to 2-3 leaves.  Repeat this process until late summer.  In the fall, do not prune these species again, as this can cause another flush of growth that may not harden off before the first frost, which can result in dieback.

Hornbeam and Beech do not respond well to defoliation or partial defoliation, as they will likely produce an unbalanced second flush of growth and may experience some twig dieback.  Rather than defoliation, it is best to perform leaf cutting in May at the same time the shoots are cut back.  Leaf cutting involves cutting each remaining leaf on the external canopy of the tree in half to allow more light to penetrate to the interior, weaker areas of the tree.

For a more in-depth look at pruning techniques, please consider joining our online bonsai learning platform Bonsai-U!

Wiring and Styling

Wiring and styling hornbeam and beech bonsai is best done either in the winter, just after the leaves have fallen or in late spring, just after the new leaves have hardened off.  Keep in mind that if you wire in winter, it is best to avoid heavily bending branches, as this can cause dieback in the subsequent spring season.  Utilize aluminum wire for these species, as it is softer on the bark and will cause less damage.  Wire will likely need to be removed within 1 to 2 months after application to avoid biting into the branches.

Repotting

Repotting hornbeam and beech bonsai is best done in early Spring just as the buds begin to swell.  This usually happens sometime in March in the northern hemisphere.  When repotting, it is okay to remove all of the original soil, as these species are quite strong and respond well to this treatment.  Also, it is possible to cut up to 50% of the roots without subsequently weakening these species.

Use a slightly more water-retentive soil medium, such as Aoki Blend or a mixture of akadama, lava rock and pumice in a ratio of 2:1:1.  The soil particle size should be approximately 3/16 inch (4mm) for medium and large trees, and slightly small for shohin size bonsai.

Watering

Hornbeam and Beech bonsai do well if kept slightly moist.  As a general guideline, check the water twice per day during the growing season from early Spring through late Fall.  Most hornbeam and beech bonsai will need to be watered at least once per day, and sometimes twice per day, during this period.  Water as the soil surface becomes dry and avoid misting the foliage, as this can lead to burn and disease.  In the winter months, check once per day and water as needed, which could be as little as once every 5-7 days depending on the climate and the individual hornbeam or beech bonsai.

Fertilization

Fertilizing hornbeam and beech bonsai will be dependent on the stage of development of the tree.  For example, younger trees are best fertilized with a high-nitrogen synthetic fertilizer to rapidly increase their size and vigor, starting from the early spring through the end of the growing season.  Older, more refined hornbeam and beech bonsai should be fertilized with a milder organic fertilizer with a lower nitrogen value.  This fertilizer should only be applied after the first set of growth has completely hardened off so as to avoid producing overly large leaves.

Placement

Hornbeam and Beech bonsai trees do best if kept in full sun in the spring as the new growth is emerging.  This helps produce more vigorous growth as well as smaller leaves.  As the temperatures heat up in summer, though, place them in partial shade.  At Eisei-en, we place our hornbeam and beech bonsai under 30-40% shade cloth starting in early June through late September.

Pests/Diseases

Hornbeam bonsai are susceptible to a number of pests including aphids and scale.  The most common diseases that affect hornbeam and beech are canker, blight, and leaf spot.  For a comprehensive understanding of what fungicides and pesticides to use on your hornbeam and beech bonsai, please join Bonsai-U!