WateringTimesWatering plan, $19
Quercus ilex, WUCOLS IV

How often to water holly oak in California

In July in the Central Valley, established holly 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. Holly oak forms a dense evergreen canopy with leathery, dark green leaves and pale undersides. This Mediterranean tree suits seaside gardens and tolerates drought once established. Water a new planting while its roots establish, then follow local needs: desert ratings are higher than coastal ones.

TreeRated for 6 of 6 zones

How often to water holly 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 holly 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 holly oak with leaves drooping by midafternoon over dry soil needs a deep soak
  • Sparse new growth on holly oak calls for checking root-area moisture and looking for pests or disease
  • Browning edges on holly oak leaves warrant inspecting soil moisture before adding irrigation
  • Dark or damaged bark near the holly oak trunk base needs inspection, especially where water collects
  • Fungal growth at a holly oak base calls for a tree assessment rather than an automatic increase in watering

How to water it

  • Soak a young holly oak's root ball and the soil just beyond it, widening the circle as roots spread
  • Give established trees deep, infrequent soakings rather than light, frequent sprinkling
  • Keep irrigation away from the trunk and crown once the tree is established
  • Plant in well-drained soil, or build a raised mound where heavy clay collects water near the roots
  • Move drip emitters farther out each year to follow the expanding canopy

Through the seasons

During a holly oak's first summer, check the original root ball as well as the soil around it. Established trees tolerate drought, but their evergreen foliage does not show whether the root area is moist. Inspect the soil before adding water, including after coastal or valley winter rain. Avoid leaving this oak in persistently waterlogged ground. WUCOLS rates holly oak low water on the north-central coast, in the Central Valley, on the south coast and in South Inland. It rates moderate water in the high desert and the low desert, where the lower coastal water needs should not be assumed.

In pots

Holly oak becomes a large tree, so plan for open ground if you begin with a container specimen. Check the mix a few inches down during California summer heat, since potting soil dries faster than garden beds. Drench it until water runs from the drainage holes, then pour off whatever collects in the saucer. Use a stable pot with room for the existing root ball. In winter, check moisture beneath the surface before watering this evergreen, especially after rain.

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
0.761.52.33.00.16JAN0.26FEB0.43MAR0.61APR0.83MAY0.99JUN1.07JUL0.95AUG0.72SEP0.47OCT0.22NOV0.14DEC0.761.52.33.00.16JFM0.61AMJ1.07JAS0.47OND
Gallons per square foot per month, Central Valley. Peak 1.07 in Jul, 6.84 a year.

Monthly water need by climate zone

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

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.150.160.310.310.740.78
Feb0.210.260.320.350.930.93
Mar0.350.430.460.521.461.52
Apr0.470.610.560.641.891.95
May0.580.830.640.782.392.45
Jun0.640.990.690.922.852.79
Jul0.641.070.7913.042.85
Aug0.60.950.740.932.792.6
Sep0.50.720.60.742.142.08
Oct0.350.470.460.531.461.49
Nov0.190.220.330.360.930.96
Dec0.120.140.260.270.650.68
Year4.86.846.27.3721.2721.08

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 holly 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 holly 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 holly oak in summer?

In July, established holly oak in loam needs a deep watering about every 20 days in the Central Valley, about every 27 days 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 holly oak need per day?

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

Yes. WUCOLS rates holly 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, low water in the South Coastal zone, low water in the South Inland zone, moderate water in the High and Intermediate Desert zone, moderate water in the Low Desert zone. The monthly table above shows how the same rating translates into different gallon amounts as reference evapotranspiration changes.

How does holly oak compare to a native oak for watering?

Holly oak is a Mediterranean evergreen with drought resistance, but that does not establish identical watering needs to every California native oak. Match irrigation to its regional rating and the moisture beneath its canopy. Keep the planting site well drained.

Can holly oak share a watering zone with a lawn?

Check whether lawn irrigation leaves the holly oak planting area persistently wet. This tree needs drainage, so adjust overlapping sprinklers if they keep the soil saturated. A separate irrigation valve makes it easier to match the tree's regional water needs.

Why are my holly oak's leaves turning yellow?

Yellow leaves alone do not identify a watering problem. Holly oak remains evergreen, but some leaf fall can occur in summer. Check moisture and inspect the tree for other symptoms before changing irrigation.

Does holly oak tolerate coastal salt spray?

Holly oak is suitable for seaside gardens, including coastal hedges. Check a new coastal planting's root ball during establishment and irrigate when it is drying. Coastal suitability does not remove the need to assess soil moisture.

How large does holly oak become?

Holly oak can reach 30 to 60 feet tall with a similarly broad, rounded crown. Allow that space when choosing its permanent site. Extra irrigation is no substitute for adequate room and a draining soil.

More plant watering guides

RosemaryBougainvilleaAgapanthusGeraniumsOlive TreesFig TreesCrape MyrtleWisteria

Sources