WateringTimesWatering plan, $19
Quercus gambelii, WUCOLS IV

How often to water Gambel oak in California

In July in the Central Valley, established Gambel 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. Gambel oak is a deciduous tree or large shrub from rocky mountain soils of Utah and Colorado south to Arizona, New Mexico and northwestern Mexico. Most plants stay between 10 and 30 feet, though wetter spots can push it to 50. Its deeply lobed, dark green leaves are paler and felted underneath, and it spreads by root sprouts into groves or thickets.

TreeRated for 4 of 6 zones

How often to water Gambel 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 Gambel 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

  • Deep soil dry around a young Gambel oak during its first summer heat means a slow, deep drink is due
  • Leaves browning at the edges on a sapling in a heat wave can signal thirst
  • Yellowing leaves in soggy, poorly drained soil point to too much water
  • New sprouts popping up around the tree come from its roots, not from overwatering

How to water it

  • Water a young tree deeply and let the soil dry well between soakings
  • Cut back to occasional deep watering once established
  • Plant in full sun in well-drained, even rocky, soil
  • Remove root sprouts if you want a single tree
  • Leave fallen leaves as mulch under the canopy

Through the seasons

Water a young tree through its first few summers. Established trees need only occasional deep water in long dry spells. Leaves drop in fall and return in spring. In wetter spots it grows taller, and over time root sprouts can form a grove. WUCOLS rates Gambel oak low water on the north-central coast, in the Central Valley, in South Inland and in the high desert. WUCOLS marks it as not suited to the low desert and has not evaluated it for the south coast.

In pots

Gambel oak is best in the ground, but a seedling can start in a tall, deep pot of gritty, well-drained mix. Water when the top few inches are dry, until water runs out the base. In summer, check every few days, since a small pot dries fast in heat. Keep the saucer empty. Plant it out young, since root sprouts and a deep root system outgrow a pot fast.

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
0.300.610.921.20.16JAN0.26FEB0.43MAR0.61APR0.83MAY0.99JUN1.07JUL0.95AUG0.72SEP0.47OCT0.22NOV0.14DEC0.300.610.921.20.16JFM0.61AMJ1.07JAS0.47OND
Gallons per square foot per month, Central Valley. Peak 1.07 in Jul, 6.84 a year.

Monthly water need by climate zone

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

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.150.16–0.310.3–
Feb0.210.26–0.350.37–
Mar0.350.43–0.520.58–
Apr0.470.61–0.640.76–
May0.580.83–0.780.95–
Jun0.640.99–0.921.14–
Jul0.641.07–11.22–
Aug0.60.95–0.931.12–
Sep0.50.72–0.740.86–
Oct0.350.47–0.530.58–
Nov0.190.22–0.360.37–
Dec0.120.14–0.270.26–
Year4.86.84–7.378.51–

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 Gambel 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 Gambel 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 Gambel oak in summer?

In July, established Gambel oak in loam needs a deep watering about every 20 days in the Central Valley and about every 22 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 Gambel oak need per day?

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

Yes. WUCOLS rates Gambel 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, not evaluated in the South Coastal zone, low water in the South Inland zone, low water 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.

Does Gambel oak spread?

Yes, it spreads by root sprouts as well as by seed and can form groves or thickets. Cut sprouts if you want one trunk. Give it room otherwise.

How big does Gambel oak get?

It usually grows 10 to 30 feet tall and wide. In wetter places it can reach 50 feet. It is often shrubby.

Is Gambel oak a California native?

No, it is native from Utah and Colorado south to northwestern Mexico. It grows in rocky mountain soils. It suits dry, sunny gardens.

What soil does Gambel oak need?

It needs well-drained soil and grows well in rocky ground. Soggy soil harms it. Full sun suits it.

Is Gambel oak evergreen?

No, it is deciduous. Its lobed leaves drop in fall. New leaves return in spring.

More plant watering guides

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Sources