WateringTimesWatering plan, $19
Quercus engelmannii, WUCOLS IV

How often to water mesa oak in California

In July in the Central Valley, established mesa 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. Mesa oak, also called Engelmann oak, is a California native tree from the coastal mountains of Southern California and northwestern Baja California. It grows slowly into a broad, spreading tree 40 to 50 feet tall with bluish gray-green leaves. It is evergreen in its range but drops some leaves in summer when grown dry, and it grows wild in grassland and woodland, often near streams.

TreeCalifornia nativeRated for 4 of 6 zones

How often to water mesa 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 mesa 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

  • Bone-dry soil deep around a first-year mesa oak during summer heat means it needs water
  • Some leaf drop in late summer is a normal response to dry soil
  • Leaves yellowing with dieback in soggy soil near a lawn point to too much water
  • Wilting new growth on a young tree during a heat wave can signal thirst

How to water it

  • Water a young tree deeply, then let the soil dry far down
  • Stop routine summer water once the tree is established
  • Plant in sun to part shade in well-drained soil
  • Site it about 20 feet from a watered lawn or flower bed
  • Leave fallen leaves under the canopy as mulch

Through the seasons

Water a young tree through its first summers while roots grow deep. After that, it needs little or no summer water, and it may drop some leaves in late summer when grown dry. Do not expect it to handle cold much below 15 to 20 degrees F. WUCOLS rates mesa oak very low water on the south coast. On the north-central coast, in the Central Valley and in South Inland it carries a low water rating. WUCOLS marks it as not suited to the high desert or the low desert.

In pots

Mesa oak is a large tree that belongs in the ground, but an acorn or seedling can start in a tall, deep pot that leaves room for a long root. Fill it with a gritty, fast-draining mix. Wet it thoroughly whenever the upper few inches have dried, and let every drop drain away. In summer heat, check the pot every few days. Keep the saucer empty. Move it into the ground while it is still small, since it grows into a large tree.

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

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

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.150.160.080.31––
Feb0.210.260.080.35––
Mar0.350.430.110.52––
Apr0.470.610.140.64––
May0.580.830.160.78––
Jun0.640.990.170.92––
Jul0.641.070.21––
Aug0.60.950.190.93––
Sep0.50.720.150.74––
Oct0.350.470.110.53––
Nov0.190.220.080.36––
Dec0.120.140.070.27––
Year4.86.841.557.37––

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 mesa 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 mesa 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 mesa oak in summer?

In July, established mesa oak in loam needs a deep watering about every 20 days in the Central Valley, about once a month or less on the south coast 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 mesa oak need per day?

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

Yes. WUCOLS rates mesa 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, very low water in the South Coastal zone, low 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 is my mesa oak dropping leaves in summer?

It is evergreen in its range but sheds some leaves in summer when grown dry. That is normal. Avoid heavy summer watering in response.

Can I plant mesa oak near my lawn?

It does best about 20 feet away from a watered lawn or flower bed. Its best spot is away from regular irrigation. Group it with other dry plants.

How fast does mesa oak grow?

It grows slowly, about 2 feet a year in good conditions. It becomes a broad tree. Plan for a wide canopy.

Where does mesa oak grow naturally?

It is native from about Pasadena south into Baja California. It is found in grassland and woodland, often near streams. Southern oak woodland is its home community.

How cold hardy is mesa oak?

Do not expect it to be hardy much below 15 to 20 degrees F. It suits areas with mild winters. Choose another oak where winters turn harsh.

More plant watering guides

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Sources