WateringTimesWatering plan, $19
Quercus kelloggii, WUCOLS IV

How often to water California black oak in California

In July in the Central Valley, established California black oak 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. California black oak is a native deciduous oak of the coast ranges and Sierra Nevada, usually around 50 feet tall. Its large, glossy leaves have deep lobes that end in bristle tips, and fall color runs yellow, orange and red. It likes sun, acidic soil and moderate water. It handles drought better than garden plants, but not as well as many native trees.

TreeCalifornia nativeRated for 4 of 6 zones

How often to water California black 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 California black 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

  • Ground dry 2 feet below the surface out past the branch tips calls for a long soak on a black oak still getting established
  • Leaves browning at the edges in interior heat can indicate drought stress or too much sun on a young tree
  • Early leaf drop in late summer can follow a long dry spell
  • Yellowing leaves and dieback near a constantly wet trunk base suggest overwatering

How to water it

  • Water broadly beyond the drip line, keeping the trunk base dry
  • Soak deeply, then let the upper soil dry before the next soak
  • Plant in acidic, well-drained soil in sun, with afternoon shade for young trees inland
  • Protect young trees from deer for the first few years
  • Mulch widely instead of planting lawn under the canopy

Through the seasons

Water a young black oak deeply through its first several summers so roots grow down. Established trees tolerate dry spells but should not be pushed as hard as other native oaks. With regular deep water it can put on about 2 feet a year. It is deciduous, coloring in fall and resting in winter when rain covers its needs. Along the north-central coast WUCOLS lists this oak as low water. Moderate water is its WUCOLS rating in the Central Valley, along the south coast and in South Inland. The high desert and low desert are listed by WUCOLS as not suited.

In pots

California black oak is a large tree and should go in the ground young. A seedling can spend a year in a deep, tall container of acidic, well-drained mix. Feel the mix a few inches down and soak it once that layer has dried. A small pot in inland heat can dry out within days. Pour off any water left in the saucer. After leaf drop, water lightly until you plant it, ideally before the next warm season.

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

California Black Oak: gallons per square foot per month, by WUCOLS climate zone

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.150.40.780.78––
Feb0.210.650.810.87––
Mar0.351.091.151.3––
Apr0.471.521.41.61––
May0.582.081.611.95––
Jun0.642.481.742.29––
Jul0.642.671.982.51––
Aug0.62.391.862.33––
Sep0.51.81.491.86––
Oct0.351.181.151.33––
Nov0.190.560.840.9––
Dec0.120.340.650.68––
Year4.817.1115.518.41––

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 California black oak. 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 California black oak 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 California black 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 California black oak in summer?

In July, established California black oak 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 California black oak need per day?

In July in the Central Valley, established California black oak 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 California black oak change across California?

Yes. WUCOLS rates California black oak separately for each of the six California climate zones: low 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, not suited to this region 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.

How fast does California black oak grow?

With regular deep water it can grow about 2 feet a year. Where it is unhappy, it may grow only an inch. Good drainage and acid soil help.

Does California black oak need acid soil?

Yes, it tolerates rich soils if they are acidic but not most neutral to alkaline soils. It also grows on serpentine. Test soil before planting.

Is California black oak drought tolerant?

It is drought tolerant compared with typical garden plants. Do not push it as far as other native trees. Give deep summer soaks in long dry spells.

Do deer eat young black oaks?

Yes, protect young trees from deer for the first few years. Cages or fencing work well.

What color are black oak leaves in fall?

They turn yellow, orange and sometimes red. Leaves drop for winter.

More plant watering guides

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Sources