Cherry / Prunus

Prunus is a large and culturally weighty genus that includes most of the spring-flowering bonsai associated with East Asian aesthetic tradition. The genus includes Prunus serrulata (Japanese flowering cherry, sakura), Prunus mume (Japanese apricot, ume — the species that flowers earliest, often in February on bare wood), Prunus persica (peach), Prunus avium (sweet cherry), Prunus salicina (Japanese plum), and many more. For bonsai purposes the species share enough care characteristics to be covered together, with cultivar-specific notes.

The cultural weight is substantial. Hanami (cherry blossom viewing) in Japan dates back over 1,200 years and remains a major annual cultural event. Ume blossom viewing predates cherry viewing and is the traditional symbol of spring's arrival. Both species have been bonsai subjects for centuries, with refined techniques and traditional aesthetic conventions accumulated over generations of work.

Practical reality for UK growers is mixed. Prunus bonsai are demanding compared to most flowering species. The genus shares Rosaceae disease vulnerabilities — silver leaf (Chondrostereum purpureum), bacterial canker (Pseudomonas syringae), and various fungal issues are all serious concerns. Pruning timing matters more than for most species — wrong-time pruning can introduce disease that proves fatal. And many cultivated Prunus are grafted onto rootstocks that show through with time, complicating long-term bonsai work.

For new growers wanting flowering bonsai, start with Chaenomeles (entry #23) or crab apple (entry #18). After 2–3 years of bonsai experience including managing disease pressure on Rosaceae species, consider Prunus.

The single most important pruning rule for the entire genus: avoid winter pruning. Cut wounds in winter and early spring are infection points for silver leaf and bacterial canker. Major structural work should happen in mid-summer (June–July) when the tree's defences are most active. This is the opposite of most deciduous bonsai pruning advice and is critical for Prunus survival.

Daily through the growing season. Prunus is moderately thirsty and consistent watering produces better flowering and fruiting.

In hot summer weather, twice daily for trees in shallow pots. In winter while dormant, reduce watering significantly.

Tap water of any hardness is fine.

Weekly liquid feed from late April through to mid-September. Slow-release organic pellets in spring and early summer.

For flowering species, switch to high-K low-N feed from mid-July through August to support next year's flower bud development. Stop feeding by late September.

Don't feed during flowering — energy goes to flowers rather than vegetative growth.

Free-draining and slightly acidic. The genus tolerates a range of substrates.

Repot every 2–3 years on young trees, every 3–4 on mature specimens. The window is mid-February through to early April. Repot as buds swell.

Prunus tolerates moderate root work — up to a third of the root mass on healthy trees. The species recovers reasonably quickly but is more disease-prone after repotting than tougher species — clean tools and clean conditions matter.

Don't combine repotting with major pruning in the same year. The tree needs all its energy for one or the other.

The critical Prunus rule: avoid winter and early spring pruning. Cut wounds in cold conditions are infection points for silver leaf disease, which is frequently fatal.

Major structural pruning should happen in mid-summer (June–July), after flowering and during the period when tree defences are most active and wounds heal fastest. This is the opposite of standard deciduous bonsai pruning timing.

Through the growing season, light pinching of new shoots back to 2–3 leaves once 4–5 develop. The species flowers on previous year's wood, so leave some shoots to extend through summer to provide flowering display.

After flowering ends (May for cherry, March for ume), cleanup pruning is acceptable.

Use sharp tools, disinfect between trees, and apply cut paste or sealant to larger wounds. The species responds badly to torn or ragged cuts.

Defoliation isn't a useful technique for Prunus and may introduce disease through stress.

Wire after leaves harden in early summer. Prunus bark is thin and marks visibly — apply loosely and check fortnightly. Aluminium for almost all work; copper rarely needed.

The species' fast growth means wire bites in quickly. Many Prunus growers minimise wire use and rely on directional pruning, accepting limitations.

Informal upright is the natural fit. Twin-trunk and multi-trunk styles work well. The genus suits naturalistic compositions that showcase the spring flowering display.

For P. mume specifically, the literati style works particularly well — referencing the classical Japanese painting tradition of single twisted ume trunks against snow.

Cascade and semi-cascade are uncommon but possible. Formal upright doesn't suit most species in the genus.

The flowering display is the genus's main aesthetic asset — styling should ensure flowering wood is clearly visible from typical viewing angles.

Hardy across most of the UK in normal winters. Most Prunus species are rated H6 and tolerate typical British winters without complaint. Some cultivars are H5 and benefit from shelter in colder regions.

The main winter consideration is moisture management — saturated cold roots cause issues. Tilt pots for drainage.

Hard late frost on opening flowers eliminates the year's display. Shelter trees overnight if -2°C or colder is forecast during the bloom period. The flowering wood itself isn't harmed.

Never bring indoors.

Almost exclusively grafted in commercial cultivar production — onto P. avium or various dwarfing rootstocks. From seed possible but produces variable seedlings and slow flowering. Air layering possible but slow. Most quality Prunus bonsai material is purchased as grafted nursery stock from named flowering cultivars and developed over years.

The major issues are Rosaceae diseases — silver leaf and bacterial canker are the most serious concerns specific to this genus.