Pinus thunbergii
1 Japanese Black Pine bonsai in stock, from $185.00 Shipped direct from our nursery partners, with a 48-hour live-arrival guarantee. See the trees
Zones 5 to 8, outdoor only. Native to Korea and central and southern Japan.
Pinaceae (the pine family) · Evergreen conifer
Compare your tree against these to confirm the species and spot problems early.
| USDA zones | 5 to 8 in the ground [2] [5]; UF/IFAS gives 6 to 8 [4]; no source gives a zone for a pot |
|---|---|
| Indoor / outdoor | Outdoor only: pine bonsai stay outside all year [12] |
| Light | Full sun [2] [11], as much as possible [13] |
| Water | Sources differ: dry thoroughly between waterings [11]; dry slightly, never overwater [12]; never let it dry out completely [13] |
| Soil | Very free-draining bonsai mix [12] [13] |
| Repot | When roots fill the pot [11]; every 3 to 5 years once established [13] |
| Frost | Hardy to zone 5 in the ground [2] [5]; Bonsai Mirai says it cannot tolerate cold weather in a pot, wraps the container below 25°F (-4°C) and uses a greenhouse for long cold spells [11] |
| Mature height | 20 to 60 ft (6 to 18 m) [2] or up to 80 ft (24 m) [5] [6] in the ground; no source gives a bonsai size |
| Growth rate | Moderate (medium) in the landscape [2] [4] [5]; not rated as a bonsai |
| Season of interest | Dark green needles and black-gray furrowed bark all year [2]; silvery white candle buds [9] |
| Leaf reduction | Not rated by the sources we checked; needles can be shortened with bonsai techniques [13] |
| Main risks | Main risks, not ranked by any source: wet soil [11] [12]; decandling a weak tree [14]; pine wilt nematode [8] |
Japanese black pine is native to Korea and central and southern Japan [1]. Kew accepts the name Pinus thunbergii [1]; older references, UF/IFAS among them, use Pinus thunbergiana [2] [4]. Bonsai4Me calls it arguably the classic bonsai pine [13]. In the landscape it copes with sand, heat, drought and salt [2].
It is a two-flush pine: a healthy tree can push two flushes of growth in one season [11] [12], which is what makes decandling possible. Single-flush pines such as white, Scots and mugo pine must not be decandled [12].
It is not an easy tree to start with. Bonsai4Me warns that pines are hard to care for and style without experience [13]. NC State's "easy, low maintenance" rating is for a tree in the ground [2].
Foliage. Stiff, twisted, dark green needles in pairs [2] [7], stout [6]. Length varies by source, from 2.5 to 4.25 in [2] or 3 to 5 in [5] [6] up to 2.75 to 6 in (7 to 15 cm) [13].
Bark & trunk. Black-gray, furrowed and fissured [2], breaking into rough plates [5] [6], craggy with age [13].
Buds. Whitish, candle-like terminal buds [2] [9], gray or silver-white and not resinous [7]. Virginia Tech describes them as light reddish brown instead [6].
Cones. Seed cones 1.5 to 3 in long [7].
Look-alikes & how to tell them apart: Virginia Tech lists red pine, Austrian pine and Japanese red pine [6]. Japanese red pine has thin paired needles and orange to orange-red bark peeling in plates [3], not black pine's stout needles [6] and black-gray furrowed bark [2].
Figures for trees in the ground: zones 5a to 8b (NC State) [2], 5 to 8 and marginally hardy (Morton) [5], 6A to 8B (UF/IFAS) [4], zone 6 (Purdue, Oklahoma State) [7] [8].
In a pot the roots are more exposed. Bonsai Empire says pines need winter protection in containers and a cold dormancy, typically below 45°F (7°C) [12]. Bonsai Mirai wraps the container in short spells below 25°F (-4°C) and moves the tree into a greenhouse if the cold lasts [11]. In heat, Bonsai Mirai uses a deeper container, which it says gives tolerance up to 110°F (43°C) [11].
Full sun [2] [4]; Bonsai Mirai advises against shading it [11]. Too little sun gives longer needles and dieback on shaded branches [13].
Sources differ. Bonsai Mirai lets the soil dry thoroughly, then soaks the whole root mass [11]. Bonsai Empire lets it dry slightly and keeps heavy rain off the second flush, since extra water lengthens needles [12]. Bonsai4Me says the soil should never dry out completely [13] and calls black pine relatively thirsty, taking more water than Japanese white pine [13].
The high drought tolerance UF/IFAS gives [4] describes trees in the ground, not in a pot.
Use a very free-draining mix [12] [13]; the sources we checked give no recipe. Keep some old soil and do not wash the roots, to keep the helpful white mycorrhizal fungus [13]. Yellowing across the whole tree points to roots short of air in old, collapsed soil [13].
Repotting timing differs. Bonsai Mirai repots in spring before the buds swell, once roots fill the pot, removing no more than 50 to 60% of the roots [11]. Bonsai Empire repots just after the buds begin to swell [12]. Bonsai4Me prefers August to September, every 3 to 5 years once established, changing no more than a third of the soil [13].
Black pine takes heavy feeding as its candles extend in spring [11]. The sources differ around decandling:
Decandling removes the spring candles from a black or red pine to trigger a second flush in summer [14]. It is stressful, so decandle only healthy, vigorous, insect-free trees; skip a tree weakened by repotting or weather, or one whose trunk is still being grown [14].
Timing depends on climate. Bonsai Tonight goes earlier where it is cooler: late May in cool climates (Seattle), early June in moderate ones (San Francisco Bay Area), mid to late June in warm ones (Los Angeles, much of the Midwest), early to mid July in hot ones (much of the South) [14]. Bonsai Empire says early to mid summer, leaving a stub of about 1/4 in (6 mm) [12]; its FAQ says late spring to early summer [12]. Bonsai Tonight leaves 3 to 12 pairs of needles per branch [14]. Bonsai Mirai selects shoots in early to mid November [11].
Needle pulling evens out strength: fewer needles on strong branches, more on weak ones [14] [16]. Bonsai Mirai pulls in late summer to early fall [11]. Bonsai Tonight pulled old needles at decandling in late May or early June, and waits until fall in years without decandling [15].
Pruning timing differs. Bonsai4Me makes heavy cuts in autumn, when sap flow is slower [13]. Bonsai Empire prunes structurally in late winter and warns against heavy pruning in late summer or autumn [12].
Wiring: fall, or early spring for structural work [11]; early autumn to early spring, or right after candle pruning [12]. Pines suit every style except broom [13].
Ease: Not rated by the sources we checked. Best methods: seed [2]; seed or grafting [12].
Bonsai4Me sows seed outside in early spring, as it needs frost to germinate, and grafts cultivars in late winter [13]. Black pine is also the rootstock Japanese white pine is often grafted onto [13].
Aphids, woolly adelgid and summer spider mites [11]; scale and caterpillars [12]; sawfly larvae [13]. Landscape trees also get borers and weevils [2] and Zimmerman pine moth [5]. On Long Island, Cornell blamed black turpentine beetle together with pinewood nematode for dying pines [10].
Pine wilt (pinewood nematode). Insect-carried [10]. Oklahoma State calls it the most serious problem [8], and Arkansas says it can wipe out a planting in one season [9].
Diplodia tip blight. Sources differ: NC State lists it [2] and Arkansas says Diplodia leaf blight often starts defoliating the lower branches of maturing trees [9], but UF/IFAS calls the species resistant [4].
Needle cast. Sudden needle discoloration and drop in spring, hard to cure [13]. Bonsai Mirai also lists Lophodermella, a fungal disease [11].
Normal: the oldest needles yellow and drop in early autumn [13].
No source we checked ranks these. They are the main risks the sources describe, in no particular order:
Trees from our own bench, filmed while we worked on them.
Play video (0:24)I took most of the canopy off this small Japanese black pine, by hand, one bundle of needles at a time. Plucking old and excess needles balances strength across the tree and lets light down to the interior buds, so the pine keeps budding back instead of running to the tips. The needles grow back. Drowned roots do not.
Play video (0:28)I bedded this young black pine into soil and moss on a tray, then lifted it into a pot with its roots left hanging over the side, because this tree is going to need every root it can get. Black pines take heat, wind and poor soil well. What they do not take is being kept wet.
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