WateringTimesWatering plan, $19
Pinus thunbergii, WUCOLS IV

How often to water Japanese black pine in California

In July in the Central Valley, established Japanese black pine in loam needs a deep watering about every 8 days: about 55 gallons each time under a 10 foot canopy, about 47 gallons a week. Japanese black pine is a rugged conifer from the seacoasts and rocky cliffs of Japan and Korea. It has paired dark green needles and silky white buds like candles. It grows into an irregular, spreading tree with black-gray bark and a picturesque, often curved trunk. It handles sand, salt and heat, but it still wants moist, well-drained soil.

TreeRated for 6 of 6 zones

How often to water Japanese black pine, month by month

Your city
Canopy width
10 ft
Your soil

Type your city above and the days between waterings and the gallons appear here, worked out from your city's climate table. Or read the figures by climate zone further down.

Every month, on your water days. The personal plan prints this for Japanese black pine and the rest of your yard, on the days your water supplier allows.Get the plan for $19

How this is worked out: established roots fill the top 1.5 feet of soil, and you water again when that soil has dried halfway. Loam soil holds about 1.5 inches of water per foot. Water the whole area under the branches, and skip a watering after a good soaking rain.

Which soil do you have?

Dig down a few inches, take a handful of moist soil and squeeze it.

  • Sandy: gritty, falls apart when you open your hand, will not form a ball.
  • Loam: forms a soft ball that crumbles when you poke it.
  • Clay: forms a firm, sticky ball and squeezes out into a ribbon between thumb and finger.

Still not sure? Pick loam. Most garden beds sit between sand and clay.

How to measure canopy width

A tree with its canopy width marked across the widest branches and the circle under it shaded blue

Measure across the branches, from the tips of the outer leaves on one side to the tips on the other. A tape works, or pace it out.

Water the whole circle under the branches, shown in blue. The gallons here cover that circle.

A wider canopy means more gallons each watering, not more waterings. While the tree is young, measure again each spring.

How to tell it needs water

  • Soil dry 4 to 6 inches down under the canopy of a young Japanese black pine signals that it needs a deep soak
  • New candles that stall and needles that yellow in summer heat can follow a dry root zone
  • Brown, dead shoot tips on an older tree can point to tip blight, a fungal disease, so check for it before adding water
  • Yellowing needles and a thinning crown over soil kept wet near the trunk warrant a check for root rot
  • Sticky needles, scale or caterpillars on new growth are pest problems, not signs of thirst

How to water it

  • Give a young black pine slow water over the nursery root ball and the soil just outside it
  • Wet the soil about 18 inches deep, and let the upper several inches dry out between soakings
  • Plant in full sun in moist, well-drained, fertile soil, or in sand near the coast
  • Keep sprinklers off the trunk so the root crown dries between soakings
  • Move emitters outward with the canopy, since the crown spreads wide with age

Through the seasons

Young Japanese black pines need deep soakings for their first two or three summers as roots move into native soil. Older trees do well with fewer, deeper summer waterings, letting the topsoil dry a little in between. It stays evergreen, and its white candles push out the new growth. Coastal and Central Valley rain usually covers winter, while desert trees need soil checks in dry spells. WUCOLS gives it a moderate water rating on the north-central coast, in the Central Valley, on the south coast and in South Inland. It rates moderate water in the high desert and the low desert too.

In pots

Japanese black pine is a classic bonsai and patio pine, and it takes well to container life. Use a gritty, fast-draining mix and check it daily in hot weather, since a small pot dries quickly. Water until it runs from the drainage holes, then let the surface dry slightly before watering again. Keep the pot in full sun. In winter, water when the mix begins to dry, and give the pot a long soak now and then to clear salts.

1 Your climate zone six WUCOLS zones, each from its own reference city
2.67gal per sq ft in JulyModerate water use in the Central Valley zone
A year
17.11 gal per sq ft
Reference
Sacramento climate table
Counts
Plant need, before sprinkler losses
0.761.52.33.00.4JAN0.65FEB1.09MAR1.52APR2.08MAY2.48JUN2.67JUL2.39AUG1.8SEP1.18OCT0.56NOV0.34DEC0.761.52.33.00.4JFM1.52AMJ2.67JAS1.18OND
Gallons per square foot per month, Central Valley. Peak 2.67 in Jul, 17.11 a year.

Monthly water need by climate zone

Japanese Black Pine: gallons per square foot per month, by WUCOLS climate zone

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.370.40.780.780.740.78
Feb0.530.650.810.870.930.93
Mar0.871.091.151.31.461.52
Apr1.181.521.41.611.891.95
May1.462.081.611.952.392.45
Jun1.612.481.742.292.852.79
Jul1.612.671.982.513.042.85
Aug1.492.391.862.332.792.6
Sep1.241.81.491.862.142.08
Oct0.871.181.151.331.461.49
Nov0.470.560.840.90.930.96
Dec0.310.340.650.680.650.68
Year1217.1115.518.4121.2721.08

How this is worked out: the WUCOLS water rating for each zone times that zone’s climate for the month. A dash means WUCOLS does not rate the plant there. The figures are what the plant uses, before sprinkler losses.

Plants with the same water needs 16

Rated moderate water in the Central Valley, like Japanese black pine. Plants that drink alike can share one valve and one schedule.

Citrus TreesCitrus spp.moderate water, Central Valley2.67 gal/sq ft in JulyJapanese MapleAcer palmatummoderate water, Central Valley2.67 gal/sq ft in JulyAvocado TreesPersea americanamoderate water, Central Valley2.67 gal/sq ft in JulyMagnolia TreesMagnolia grandiflora ssp. & cvs.moderate water, Central Valley2.67 gal/sq ft in JulyPalm TreesSyagrus romanzoffiana (Arecastrum romanzoffianum)moderate water, Central Valley2.67 gal/sq ft in JulyApple TreesMalus spp. (edible) e.g, 'Anna' (low chill variety for low desert)moderate water, Central Valley2.67 gal/sq ft in JulyPeach TreesPrunus spp. ediblemoderate water, Central Valley2.67 gal/sq ft in JulyPersimmon TreesDiospyros kakimoderate water, Central Valley2.67 gal/sq ft in JulyAmur MapleAcer ginnalamoderate water, Central Valley2.67 gal/sq ft in JulyFernleaf MapleAcer japonicummoderate water, Central Valley2.67 gal/sq ft in JulyBox ElderAcer negundomoderate water, Central Valley2.67 gal/sq ft in JulyNorway MapleAcer platanoidesmoderate water, Central Valley2.67 gal/sq ft in JulyRed MapleAcer rubrummoderate water, Central Valley2.67 gal/sq ft in JulyChinese MapleAcer truncatummoderate water, Central Valley2.67 gal/sq ft in JulyRed BuckeyeAesculus paviamoderate water, Central Valley2.67 gal/sq ft in JulyRed HorsechestnutAesculus x carneamoderate water, Central Valley2.67 gal/sq ft in July

Similar plants that need less water 16

Rated lower than Japanese black pine in the Central Valley. Worth a look for a new bed or a lawn replacement.

Olive TreesOlea europaea ssp. & cvs.low water, Central Valley1.07 gal/sq ft in JulyFig TreesFicus carica ssp. & cvs.low water, Central Valley1.07 gal/sq ft in JulyCrape MyrtleLagerstroemia spp., hybrids & cvs.low water, Central Valley1.07 gal/sq ft in JulyAloeAloe spp. & cvs.low water, Central Valley1.07 gal/sq ft in JulyPomegranate TreesPunica granatumlow water, Central Valley1.07 gal/sq ft in JulyEucalyptusEucalyptus polyanthemoslow water, Central Valley1.07 gal/sq ft in JulyPine TreesPinus canariensislow water, Central Valley1.07 gal/sq ft in JulyJunipersJuniperus spp. & cvs.low water, Central Valley1.07 gal/sq ft in JulyTexas Red OakQuercus buckleyilow water, Central Valley1.07 gal/sq ft in JulyPortuguese OakQuercus faginealow water, Central Valley1.07 gal/sq ft in JulySoapbark TreeQuillaja saponarialow water, Central Valley1.07 gal/sq ft in JulyNecklace TreeSophora affinislow water, Central Valley1.07 gal/sq ft in JulyBailey AcaciaAcacia baileyanalow water, Central Valley1.07 gal/sq ft in JulySilver WattleAcacia dealbatalow water, Central Valley1.07 gal/sq ft in JulyGreen WattleAcacia decurrenslow water, Central Valley1.07 gal/sq ft in JulySydney Golden WattleAcacia longifolialow water, Central Valley1.07 gal/sq ft in July
Minutes for your sprinklers

Turn this into minutes on your water days

Every city page has a calculator that takes Japanese black pine, your sprinkler type and the month, and gives the minutes per water day for that supplier's schedule. Or put it in a zone of the personal watering plan and get all twelve months printed.

Questions people ask

How often should I water Japanese black pine in summer?

In July, established Japanese black pine in loam needs a deep watering about every 8 days in the Central Valley, about every 11 days on the south coast and about every 9 days in the South Inland zone. Sandy soil holds less water, so waterings come closer together. Clay stretches them. Check the soil before each watering and skip one after a soaking rain.

How much water does Japanese black pine need per day?

In July in the Central Valley, established Japanese black pine needs about 6.8 gallons a day under a 10 foot canopy and about 27 gallons a day under a 20 foot canopy. Give it in deep waterings spread days apart rather than a little every day, so the whole root zone gets wet.

Does watering for Japanese black pine change across California?

Yes. WUCOLS rates Japanese black pine separately for each of the six California climate zones: moderate water in the North-Central Coastal zone, moderate water in the Central Valley zone, moderate water in the South Coastal zone, moderate water in the South Inland zone, moderate water in the High and Intermediate Desert zone, moderate water in the Low Desert zone. The monthly table above shows how the same rating translates into different gallon amounts as reference evapotranspiration changes.

Is Japanese black pine good near the ocean?

Yes. It grows wild on seacoasts and rocky cliffs and is used to stabilize dunes. It tolerates sand and salt, though young trees still need deep soakings to establish.

Why are the tips of my black pine turning brown?

On older trees, brown shoot tips often point to Diplodia tip blight, a fungal disease that appears as trees age. Prune out dead tips in dry weather, and avoid letting the tree go dry for long. Rusts and cankers can cause similar dieback.

How big does Japanese black pine get?

In landscapes it often reaches 20 to 60 feet with a broad, irregular crown, though it can grow taller in the wild. It is also kept small as bonsai. Give a garden tree room to spread.

How is Japanese black pine different from Austrian pine?

The two are often confused in the nursery trade. Austrian pine keeps a strong central leader, while Japanese black pine has no prominent leader and grows irregular. The silky white buds also mark Japanese black pine.

Do I need to prune Japanese black pine?

Pruning is not required, and it needs little maintenance. Remove only dead or damaged branches.

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Sources