WateringTimesWatering plan, $19
Quercus rubra, WUCOLS IV

How often to water red oak in California

In July in the Central Valley, established red 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. Red oak, also called northern red oak, is a fast growing deciduous shade tree from eastern North America. Its broad, rounded crown reaches 50 to 75 feet tall and wide. The large leaves carry seven to eleven bristle-tipped lobes and turn reddish brown in fall. It prefers acidic, well-drained soil and deep, unhurried watering.

TreeRated for 4 of 6 zones

How often to water red 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 red 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 6 inches down beneath the canopy edge signals that a red oak needs a deep soak
  • Leaves wilting or browning at the margins in a long, hot dry spell can indicate a dry root zone
  • Yellow leaves with green veins point to chlorosis from soil that is not acidic enough, not to thirst
  • Yellowing leaves and a thinning canopy over soil that stays soggy can indicate poor drainage
  • Acorns dropping in fall are normal, and each one takes two seasons to ripen on the tree

How to water it

  • Water a young red oak over its root ball and an expanding ring of soil around it
  • Move water to the outer canopy and beyond as the tree matures, keeping the trunk base dry
  • Soak slowly so moisture reaches 18 inches or more, then let the upper soil dry before the next soak
  • Plant in well-drained, slightly acidic soil, and mulch with fallen leaves or wood chips
  • Keep lawn and frequently watered beds out of the root zone so the soil can dry between soakings

Through the seasons

A young red oak wants deep watering through its first two or three summers while its roots spread. Later, give it deep, well-spaced soakings whenever the dry season sets in. WUCOLS gives red oak a moderate water rating on the north-central coast, in the Central Valley, on the south coast and in South Inland. WUCOLS marks it as not suited to the high desert or the low desert. New leaves appear in spring beside inconspicuous flowers and turn reddish brown before they fall. Rain usually carries the leafless tree through winter on the coast and in the valley.

In pots

Red oak becomes a large shade tree, so a container suits only a seedling or young tree before planting out. Use a deep pot with open holes and an acidic, well-drained mix. Check the mix 2 to 3 inches down every few days in summer heat, and water when it is dry there. Let excess drain, then empty the saucer. After leaf drop, water lightly but do not let the mix dry out completely. Plant it in the ground while young, since it transplants easily.

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

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

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.370.40.780.78––
Feb0.530.650.810.87––
Mar0.871.091.151.3––
Apr1.181.521.41.61––
May1.462.081.611.95––
Jun1.612.481.742.29––
Jul1.612.671.982.51––
Aug1.492.391.862.33––
Sep1.241.81.491.86––
Oct0.871.181.151.33––
Nov0.470.560.840.9––
Dec0.310.340.650.68––
Year1217.1115.518.41––

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 red 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 red 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 red 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 red oak in summer?

In July, established red 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 red oak need per day?

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

Yes. WUCOLS rates red oak 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, 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.

Why are my red oak leaves yellow with green veins?

That pattern is chlorosis, which this oak develops when the soil is not acidic enough. It is a soil chemistry problem rather than a watering one. Ask a local nursery or extension office about correcting soil pH.

How long do red oak acorns take to ripen?

Its acorns need two growing seasons to mature. Trees start bearing at 20 to 25 years and produce heavy crops later. Squirrels, deer and birds eat them.

How big does red oak get?

It can reach 50 to 75 feet tall and as wide, with a crown that branches close to the ground. Plant it well away from buildings. Its root zone expands with the canopy, so widen watering over time.

Can you overwater a red oak?

Yes. It needs well-drained soil, and constantly wet ground harms the roots. Let the upper soil dry between deep soakings, and keep it out of frequently watered lawn.

What color are red oak leaves in fall?

They turn reddish brown before dropping. During the growing season the large leaves are green above and grayish white beneath. Leaf fall in autumn is normal and does not mean the tree is dry.

More plant watering guides

Persimmon TreesGrapevinesArborvitaeBambooCalla LiliesCannasClematisLilacs

Sources