Senjumaru Japanese black pine
BeginnerPinus thunbergii 'Senjumaru'
A yatsubusa black pine that arose as a sport of the black pine 'Kotobuki'. It buds prolifically, making branch development easy, and has short, thick, deep-green needles. Quick to form a tree, it suits shohin bonsai and is popular abroad.
About
Senjumaru is a yatsubusa cultivar of Japanese black pine. According to a 2011 Shikoku Shimbun article, a grower at a bonsai nursery in Kokubunji, Takamatsu, Kagawa, found that a single upper branch on a black pine 'Kotobuki' had mutated into a yatsubusa sport, and named it 'Senjumaru' (the discovery was 12 years before the article). The nursery still keeps the parent tree, Kotobuki below and yatsubusa above. This is why sellers often label it 'black pine Kotobuki yatsubusa': 'Kotobuki' is the name of the parent line. Senjumaru buds heavily, making branch development easy, and has short, thick, deep-green needles; because a tree takes shape quickly it is considered easy to enjoy, especially as shohin, and it is popular overseas. It is propagated mainly by low grafting near the base of black pine rootstock, and the article notes that thick-needled pines root poorly from cuttings. Care follows ordinary black pine: outdoors in sun and airflow, on the dry side, refining the foliage with candle pinching, summer bud-cutting and needle thinning. Plants range from grafted seedlings to shohin trees about 10 years old.
Size of the Senjumaru Japanese black pine
The Senjumaru Japanese black pine grows to Yatsubusa, suited to shohin (a tree grown about 10 years to 22 cm tall has been reported).
Basic Info
Origin
Japan (found as a sport of black pine 'Kotobuki' in Takamatsu, Kagawa)
Lifespan
A recent cultivar; little data on lifespan
Size
Yatsubusa, suited to shohin (a tree grown about 10 years to 22 cm tall has been reported)
Temperature
-5〜35℃
Watering & Fertilizer
Fertilizer (April–September, except the rainy season and midsummer)
Growing Tips
Light & placement
Outdoors in sun and airflow; in winter a sunny spot out of wind and frost
Watering
Prefers to dry between waterings: thoroughly when the surface dries—once daily in spring/autumn, twice in midsummer, every 3 days in winter
Temperature & overwintering
Black pine tolerates heat, salt wind and drought (USDA zones 5–8). Protect small pots from freezing in cold areas
Soil & repotting
Free-draining mix; repot every 3–4 years in early April to early May as new growth starts
Fertilizer
Organic solid fertilizer monthly April–September, except the rainy season and midsummer
Pruning & styling
Buds are numerous—thin from the strongest. Cut candles in late June–July to even out second flush; thin old needles in December. Wire in dormancy
Pests & cautions
Watch for aphids, sooty mould and needle cast. Most plants are grafted—remove rootstock shoots early
Senjumaru Japanese black pine FAQ
QWhat is the growing difficulty level for Senjumaru Japanese black pine?
Beginner. A variety suitable for beginners. No special equipment or experience is required—you can grow it without problems by setting up a basic cultivation environment.
QHow large does Senjumaru Japanese black pine get?
The mature size of Senjumaru Japanese black pine is Yatsubusa, suited to shohin (a tree grown about 10 years to 22 cm tall has been reported). This may vary slightly depending on cultivation environment and individual differences.
QHow should I water and fertilize Senjumaru Japanese black pine?
Senjumaru Japanese black pine: watering & fertilizer — Fertilizer (April–September, except the rainy season and midsummer). Aim for appropriate frequency and amount.
QWhat is the typical price for Senjumaru Japanese black pine?
The price of Senjumaru Japanese black pine varies significantly by variety, characteristics, size, and lineage. Please check GrowerDirect's price guide for the latest market information.
Last updated: September 23, 2026
References & Sources
Edited & verified by: GrowerDirect Editorial Team
The classifications, regulations, and growing data on this page are created and verified based on the primary information database below.
Taxonomy & Authority
Regulations & Conservation Status
Not listed by CITES and not regulated for domestic sale. Not a registered variety under the Plant Variety Protection Act (no entry for 'Senjumaru' in the MAFF database, checked Sept 2026).
Sources: Species+ (CITES listing search) / MAFF Plant Variety Registration Database
Regulations may change. Always verify the latest information with the relevant authorities.
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