Hawthorns bonsai grow with relatively short nodes and so produce many buds. Depending upon the hormonal messages that the bud receives it can develop into leaves, a flowering spur, a secondary branch, a water shoot or perhaps just a thorn. Controlling these hormonal messages within the tree will ensure good characterful development and as a side benefit flowering.
Often when we collect old hawthorn they will flower very well but this declines over a few seasons. This happens because the trees situation will have improved and it gradually reverts to a ‘juvenile’ state of expansion growth. Over time energy is diverted away from mature fruiting growth towards expansion growth and flowering quickly declines.
The hawthorn is the plant that grows like a shrub in most cases and it takes many years to develop thick trunks. For bonsai, it has a number of good characteristics: small leaves, white flowers, red berries and a nice bark on old trees. Additionally, it is quite easy to achieve a fine ramification on hawthorns. Unfortunately, it is not easy to dig up hawthorns and many specimens die after being collected. Because of this carefulness and experience are important if you want to collect an old hawthorn yourself.
The following technique should only be applied to relatively mature trees with a fair level of secondary branching, not raw material in need of primary branch growth etc’. The hawthorn resents root disturbance and will only normally need to be re-potted every 3-5 years. Fertilise the tree very well from February (late winter) until late autumn with a balanced fertiliser.
1 Family: Rosaceae
Lighting: Full sun, partial shade in the hottest part of midsummer.
Temperature: Zones 6 through 11.. Most hawthorns dislike extreme heat. Resistant to windy conditions.
Watering: Generous – do not allow the soil to dry out completely. Increase the amount of water in the summer. C. marshal is an especially thirsty plant, as its native habitat is the marsh, and will die if ever allowed to dry out. Hawthorn likes to be misted in dry weather, but avoid misting the flowers when in bloom. Moisture trays can be used to provide needed humidity, especially for C. marshal.
Feeding: Every 14-30 days from spring-autumn, stopping for a month in midsummer. Use half-strength plant food or bonsai food.
Pruning and wiring: Prune back shoots to the first two leaves as necessary. Hawthorn grows quickly and needs constant pruning to keep under control.