WateringTimesWatering plan, $19
Quercus garryana, WUCOLS IV

How often to water Oregon white oak in California

In July in the Central Valley, established Oregon white oak in loam needs a deep watering about every 20 days: about 55 gallons each time under a 10 foot canopy, about 19 gallons a week. Oregon white oak is a native deciduous oak that grows from British Columbia south to the Tehachapi Mountains. It can be a tree 40 to 90 feet tall or a twisted, shrubby oak on poor ground. Deeply lobed, glossy leaves and pale, almost bone-white bark give it a striking winter look. It is a low water tree once established.

TreeCalifornia nativeRated for 3 of 6 zones

How often to water Oregon white oak, 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 Oregon white oak 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 2 feet down beyond the canopy in a young tree's first summers signals it needs a deep soak
  • Leaves browning at the edges in a young tree's first hot summer can indicate a dry root zone
  • Early leaf drop in late summer can follow a long dry spell on a young tree
  • Thinning crown and dieback near a constantly wet trunk base suggest overwatering

How to water it

  • Water a young tree in a wide ring out past the branches, never at the trunk
  • Soak deeply, then let the soil dry well down before repeating
  • Plant in sun to part shade in well-drained soil
  • Keep lawn irrigation and summer sprinklers away from the root zone
  • Taper water once the tree is established

Through the seasons

Water a young Oregon white oak deeply through its first few summers so roots grow down. Established trees need little summer water and resent constant wet soil at the trunk. It is deciduous, and its pale bark stands out in winter. In the wild it grows both on dry, rocky slopes and in seasonally flooded areas. WUCOLS rates Oregon white oak low water on the north-central coast, in the Central Valley and on the south coast. WUCOLS marks it as not suited to South Inland, and has not evaluated it for the high desert or the low desert.

In pots

Oregon white oak is a long-lived tree for the ground, not a container. An acorn seedling can grow in a deep, tall pot for a year before planting. Water when the top few inches of mix are dry, letting it drain fully. In summer, check every few days. Empty the saucer. Plant it out within a year, before roots circle the pot. Keep the pot in full sun so the seedling grows sturdy.

1 Your climate zone six WUCOLS zones, each from its own reference city
1.07gal per sq ft in JulyLow water use in the Central Valley zone
A year
6.84 gal per sq ft
Reference
Sacramento climate table
Counts
Plant need, before sprinkler losses
0.270.540.801.10.16JAN0.26FEB0.43MAR0.61APR0.83MAY0.99JUN1.07JUL0.95AUG0.72SEP0.47OCT0.22NOV0.14DEC0.270.540.801.10.16JFM0.61AMJ1.07JAS0.47OND
Gallons per square foot per month, Central Valley. Peak 1.07 in Jul, 6.84 a year.

Monthly water need by climate zone

Oregon White Oak: gallons per square foot per month, by WUCOLS climate zone

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.150.160.31–––
Feb0.210.260.32–––
Mar0.350.430.46–––
Apr0.470.610.56–––
May0.580.830.64–––
Jun0.640.990.69–––
Jul0.641.070.79–––
Aug0.60.950.74–––
Sep0.50.720.6–––
Oct0.350.470.46–––
Nov0.190.220.33–––
Dec0.120.140.26–––
Year4.86.846.2–––

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 low water in the Central Valley, like Oregon white oak. Plants that drink alike can share one valve and one schedule.

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 Oregon white oak, 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 Oregon white oak in summer?

In July, established Oregon white oak in loam needs a deep watering about every 20 days in the Central Valley and about every 27 days on the south coast. 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 Oregon white oak need per day?

In July in the Central Valley, established Oregon white oak needs about 2.7 gallons a day under a 10 foot canopy and about 11 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 Oregon white oak change across California?

Yes. WUCOLS rates Oregon white oak separately for each of the six California climate zones: low water in the North-Central Coastal zone, low water in the Central Valley zone, low water 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 evaluated in the Low Desert zone. The monthly table above shows how the same rating translates into different gallon amounts as reference evapotranspiration changes.

Is Oregon white oak native to California?

Yes, it ranges from British Columbia south through California to the Tehachapi Mountains. It is a white oak, related to valley oak. It suits large native gardens.

Why is the bark so pale?

Its bark is light gray to almost white, especially striking in winter. In foggy areas moss may cover the trunk. Neither needs a change in watering.

Can Oregon white oak grow in a lawn?

Frequent lawn watering keeps the root zone too wet. Mulch under the canopy instead. Give the tree its own deep soaks while young.

How big does Oregon white oak get?

It can reach 40 to 90 feet tall as a tree, or stay shrubby at about 20 feet on poor sites. Its form is often twisted. Give it room.

Can Oregon white oak handle wet soil?

It grows in seasonally flooded areas in the wild. Year-round wet soil in a garden is different and harms it. Let the soil dry between soaks.

More plant watering guides

LavenderRosemaryBougainvilleaAgapanthusGeraniumsOlive TreesFig TreesCrape Myrtle

Sources