WateringTimesWatering plan, $19
Quercus polymorpha, WUCOLS IV

How often to water Monterrey oak in California

In July on the north-central coast, established Monterrey oak in loam needs a deep soak only about once a month or less: about 55 gallons each time under a 10 foot canopy. Monterrey oak is a fast-growing, partly deciduous oak that ranges from southern Texas through Mexico to Guatemala. Its leaves are unusually variable in shape, as its botanical name suggests, and new growth comes out a reddish bronze. Young trees grow upright and pyramidal before the crown broadens. It needs deep, spaced soakings, and it has low tolerance for salty soil or water.

TreeRated for 2 of 6 zones

How often to water Monterrey 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 Monterrey 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

  • A young Monterrey oak is ready for a deep soak when the soil beside its root ball is dry 4 inches down
  • Dull, drooping leaves on a young tree in a summer heat wave, with dry soil below, point to a dry root zone
  • Much of the canopy turning color in late winter or early spring is this oak's normal leaf change, not drought
  • Brown leaf edges where the soil or water is salty can be salt damage, since this oak has low salt tolerance
  • Leaves that yellow and thin over ground that stays soggy point to poor drainage rather than thirst

How to water it

  • Water a young Monterrey oak slowly over its root ball and a ring of soil around it, widening the ring as the canopy grows
  • Wet the soil deeply each time, then let the upper several inches dry before the next watering
  • Set drip emitters or a soaker ring under the outer canopy of an older tree and keep water off the trunk
  • Plant in full sun in loam, sand or clay, including alkaline ground, where water does not stand
  • Mulch the root zone with wood chips, leaving a bare ring of soil around the trunk

Through the seasons

Give a new Monterrey oak deep soakings through its first summers while its roots spread. In a University of California trial in Los Angeles County, trees given only occasional, mostly summer irrigation grew into strong, well formed trees. Much of the canopy colors up in late winter or early spring nearly every year, then a new flush of leaves follows. Winter rain covers the cool months on the north-central coast, where WUCOLS rates it low water. It rates moderate water on the south coast. WUCOLS has not evaluated it for the Central Valley, South Inland, the high desert or the low desert.

In pots

Monterrey oak is a large tree and suits a container only while young. Young trees set out small have established well in the ground, so plant it out early. Check the mix 2 to 3 inches down every few days in summer heat. Water until it runs from the drainage holes, then empty the saucer. Salts build up in potting mix over time, and this oak has low salt tolerance, so flush the pot with a long, slow soak now and then. In winter, check the mix during dry spells and water only once it has dried.

1 Your climate zone six WUCOLS zones, each from its own reference city
Not ratedWUCOLS does not rate Monterrey Oak for the Central Valley zone
A year
no figure
Reference
Sacramento climate table
Counts
Plant need, before sprinkler losses

WUCOLS lists Monterrey Oak as not evaluated for the Central Valley zone, so no monthly figure is computed here.

Monthly water need by climate zone

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

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.15–0.78–––
Feb0.21–0.81–––
Mar0.35–1.15–––
Apr0.47–1.4–––
May0.58–1.61–––
Jun0.64–1.74–––
Jul0.64–1.98–––
Aug0.6–1.86–––
Sep0.5–1.49–––
Oct0.35–1.15–––
Nov0.19–0.84–––
Dec0.12–0.65–––
Year4.8–15.5–––

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 not evaluated in the Central Valley, like Monterrey oak. Plants that drink alike can share one valve and one schedule.

Hawthorn MapleAcer crataegifoliumnot rated, Central Valleyno Central Valley ratingMountain MapleAcer glabrumnot rated, Central Valleyno Central Valley ratingMiyabe MapleAcer miyabeinot rated, Central Valleyno Central Valley ratingEverglades PalmAcoelorraphe wrightiinot rated, Central Valleyno Central Valley ratingPink CedarAcrocarpus fraxinifoliusnot rated, Central Valleyno Central Valley ratingYellowwoodAfrocarpus falcatus (Podocarpus falcatus)not rated, Central Valleyno Central Valley ratingNew Caledonian PineAraucaria columnaris (A. cookii)not rated, Central Valleyno Central Valley ratingFormosa Sugar PalmArenga englerinot rated, Central Valleyno Central Valley ratingNeemAzadirachta indicanot rated, Central Valleyno Central Valley ratingBismarck PalmBismarckia nobilisnot rated, Central Valleyno Central Valley ratingAmerican HornbeamCarpinus caroliniananot rated, Central Valleyno Central Valley ratingJapanese HornbeamCarpinus japonicanot rated, Central Valleyno Central Valley ratingAmerican YellowwoodCladrastis kentukeanot rated, Central Valleyno Central Valley ratingPagoda DogwoodCornus alternifolianot rated, Central Valleyno Central Valley ratingGiant DogwoodCornus controversanot rated, Central Valleyno Central Valley ratingButterfly PalmDypsis lutescens (Areca)not rated, Central Valleyno Central Valley rating
Minutes for your sprinklers

Turn this into minutes on your water days

Every city page has a calculator that takes Monterrey 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 much water does Monterrey oak need per day?

In July on the north-central coast, established Monterrey oak needs about 1.6 gallons a day under a 10 foot canopy and about 6.5 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 Monterrey oak change across California?

Yes. WUCOLS rates Monterrey oak separately for each of the six California climate zones: low water in the North-Central Coastal zone, not evaluated in the Central Valley zone, moderate water in the South Coastal zone, not evaluated 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.

Why does my Monterrey oak change color in late winter?

This oak is partly deciduous. Trial trees in Los Angeles County showed color over most of the canopy at the end of winter or start of spring, almost every year and whatever the temperature. New leaves follow, often reddish bronze, so this is a normal leaf change and not thirst.

How fast does Monterrey oak grow?

It is a fast grower. Trial trees planted small in 2005 averaged about 44 feet tall after 17 years. Expect an upright, pyramidal young tree that broadens with age.

Why are Monterrey oak leaves all different shapes?

Its leaves are unusually variable, from oblong to oval or lance-shaped, and lobed or toothed. The name polymorpha refers to that variety. Different leaf shapes on one tree are normal and say nothing about water.

Is Monterrey oak resistant to disease?

It is reported as more resistant to oak wilt than other oaks. It is also listed as resistant to powdery mildew, sooty mold, sudden oak death and verticillium wilt.

Does Monterrey oak grow well in coastal California?

A University of California trial found it and related Mexican oaks well suited to coastal southern California, and likely to the central coast too. Its salt tolerance is low, so keep it away from salty soil or water.

How much room does a Monterrey oak need?

It can reach about 60 feet tall and 40 feet wide. Its root damage potential is rated moderate, so plant it in a space wider than 7 feet and well back from paving. Keep it clear of overhead power lines.

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Sources