WateringTimesWatering plan, $19
Pinus parviflora, WUCOLS IV

How often to water Japanese white pine in California

In July in the Central Valley, established Japanese white 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 white pine is a slow-growing conifer from Japan, Korea and eastern China. Its fine needles come in bundles of five, often blue-green with whitish inner faces. It grows dense and pyramidal when young and spreads into a flat-topped, picturesque tree with age. It is a classic bonsai subject and does best with cool summers and sharp drainage.

TreeRated for 2 of 6 zones

How often to water Japanese white 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 white 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 inches down at the edge of a young Japanese white pine signals that it needs a deep soak
  • New growth that stays short and needles that dull in summer heat suggest the roots have dried too far
  • Yellowing needles and a weak crown over soil that stays wet point to poor drainage, which this pine dislikes
  • Orange powdery spots or swellings on twigs can signal rust disease rather than water stress
  • Sticky needles with clusters of small insects point to aphids, not thirst

How to water it

  • Water slowly under the outer branches with drip or a soaker, keeping the trunk dry
  • Soak the soil about 18 inches deep, then let the top several inches dry before watering again
  • Plant in full sun in soil that drains freely, mounding heavy clay so water never stands
  • Mulch the root zone with pine needles or bark, keeping it a few inches from the trunk
  • Widen the watered ring as the branches spread, since old trees can be as wide as they are tall

Through the seasons

A new Japanese white pine needs deep soakings through its first two or three summers while roots spread. Established trees still want deep summer soakings, spaced so the soil dries a little between them. It stays evergreen and grows slowly, putting out its new shoots in spring. Rain usually covers the cool months on the north-central coast and in the Central Valley. WUCOLS rates Japanese white pine moderate water on the north-central coast and in the Central Valley. It is marked not suited to the south coast, South Inland and the low desert. WUCOLS has not evaluated it for the high desert.

In pots

Japanese white pine is a favorite for bonsai and large patio containers, where it grows slowly for years. Use a gritty, fast-draining mix and check it daily in summer heat, since shallow bonsai pots dry fast. Water until it drains from the holes, then let the surface dry slightly before the next watering. Never leave the pot standing in water. In winter, water less but do not let the mix dry out completely.

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
0.671.32.02.70.4JAN0.65FEB1.09MAR1.52APR2.08MAY2.48JUN2.67JUL2.39AUG1.8SEP1.18OCT0.56NOV0.34DEC0.671.32.02.70.4JFM1.52AMJ2.67JAS1.18OND
Gallons per square foot per month, Central Valley. Peak 2.67 in Jul, 17.11 a year.

Monthly water need by climate zone

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

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.370.4––––
Feb0.530.65––––
Mar0.871.09––––
Apr1.181.52––––
May1.462.08––––
Jun1.612.48––––
Jul1.612.67––––
Aug1.492.39––––
Sep1.241.8––––
Oct0.871.18––––
Nov0.470.56––––
Dec0.310.34––––
Year1217.11––––

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 white 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 white 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 white 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 much water does Japanese white pine need per day?

In July in the Central Valley, established Japanese white 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 white pine change across California?

Yes. WUCOLS rates Japanese white 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, not suited to this region in the South Coastal zone, not suited to this region in the South Inland zone, not evaluated in the High and Intermediate Desert zone, not suited to this region in the Low Desert zone. The monthly table above shows how the same rating translates into different gallon amounts as reference evapotranspiration changes.

Why did my Japanese white pine lose a branch?

This tree is prone to wind damage, and its wide-spreading branches can break in storms. Plant it in a sheltered spot and prune out damaged limbs. A broken branch does not mean the tree needs more water.

How big does Japanese white pine get?

In cultivation it usually reaches 20 to 50 feet, often near 30, and spreads about as wide. It grows slowly, dense when young and flat-topped with age.

Can Japanese white pine grow in hot inland areas?

It does best where summers are cool, and heat and humidity weaken it. In hot areas, steady deep soakings and sharp drainage help, but cooler gardens suit it better.

Does Japanese white pine tolerate salt?

It has moderate salt tolerance, which helps in coastal gardens. Infrequent deep soakings carry salts below the root zone better than frequent light ones.

What are the blue Japanese white pines?

Several cultivars have short, curved blue or silver-blue needles. They need the same sharp drainage and moderate water as the green form.

More plant watering guides

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Sources