Guide for a Hawthorn (Crataegus spp.) Bonsai
Hawthorn is a classic deciduous species, prized in bonsai for its deeply fissured, rugged bark, abundant white spring flowers, and clusters of bright red autumn berries. It is a very hardy and long-lived tree.
Placement and Temperature
- Sunlight: Hawthorn requires full, direct sun all year long. Strong light is essential for dense growth, good flowering.
- Temperature: It is extremely hardy and cold-tolerant and must remain outdoors to satisfy its dormancy requirement. Protect the roots in the pot from deep, sustained freezing below -10C.
Watering and Feeding
- Watering: Water thoroughly when the topsoil is just dry. Hawthorn dislikes drying out completely during the growing season, which can cause leaf scorch and flower/berry drop. Ensure excellent drainage to prevent root rot.
- Fertilisation: Feed consistently throughout the growing season (early spring through late summer).
Pruning and Repotting
- Pruning: Hawthorn flowers and fruits on older wood (spurs). Pruning must be adjusted accordingly to preserve flowering sites.
- Structural Pruning: Done in late winter/early spring during dormancy.
- Maintenance Pruning: Use the clip-and-grow method. Cut new shoots back to 2-3 leaves to encourage ramification. Important: Allow shoots destined to become flower spurs to develop unpruned until late summer.
- Thorns: Be cautious, as many varieties have sharp thorns.
- Repotting: Repot every 2–4 years in early spring just before bud swell. Hawthorn roots strongly. Reduce the root ball by about one-third.
- Soil: Use a fast-draining, well-aerated mix (e.g., Akadama, Pumice, Lava Rock).
Wiring
- Timing: Wire in late winter/early spring.
- Wood: Hawthorn branches can be stiff and brittle, especially when older. Use careful, gradual bending techniques.
- Removal: Check the wire frequently during the growing season and remove it promptly, as the branches swell quickly and scarring is common.