WateringTimesWatering plan, $19
Quercus wislizeni, WUCOLS IV

How often to water interior live oak in California

In July in the Central Valley, established interior live oak in loam needs a deep soak only about once a month or less: about 55 gallons each time under a 10 foot canopy. Interior live oak is an evergreen native of dry valleys and foothills in the Coast Ranges and Sierra Nevada. It grows into a broad tree 30 to 70 feet tall, or a shrub in harsh sites, with thick, glossy, dark green leaves that are smooth or spiny-edged. Reddish brown bark gives it a formal look. In its native range it needs no summer water once established.

TreeCalifornia nativeRated for 5 of 6 zones

How often to water interior live 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 interior live 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

  • Glossy leaves on interior live oak staying dark and firm through a dry summer show it needs no water
  • A young tree wilting new shoots while the soil is dry deep down needs a deep soak
  • Yellowing leaves on a tree inside a watered lawn point to too much summer water
  • Chlorosis near a recent trench or septic line points to root damage, not thirst

How to water it

  • Water young trees deeply for the first few summers so roots grow down
  • Use a hose or sprinkler across the root zone rather than drip at the trunk
  • Stop summer water once it is established in its native range
  • Keep lawns well away, about 30 to 50 feet from the trunk
  • Skip fertilizer, which oaks do not want

Through the seasons

Water a young tree through its first two or three summers. After that it needs no summer water within its native range, and summer drought suits it. Interior heat raises its needs, so give occasional deep soaks in hot inland gardens. It is evergreen, and winter rain covers the cool months on the coast and in the Central Valley. WUCOLS rates interior live oak very low water on the north-central coast, in the Central Valley, on the south coast and in South Inland. The high desert carries a moderate water rating. WUCOLS marks it as not suited to the low desert.

In pots

Interior live oak belongs in the ground, but an acorn seedling can grow in a deep, narrow pot for a year while its roots form. Use a well-drained mix. Water when the top couple of inches dry, until it drains through. In summer, check every few days. Empty the saucer. Move it to its spot in fall, ahead of the rains. In winter, water only when the mix dries.

1 Your climate zone six WUCOLS zones, each from its own reference city
0.27gal per sq ft in JulyVery low water use in the Central Valley zone
A year
1.71 gal per sq ft
Reference
Sacramento climate table
Counts
Plant need, before sprinkler losses
0.761.52.33.00.04JAN0.07FEB0.11MAR0.15APR0.21MAY0.25JUN0.27JUL0.24AUG0.18SEP0.12OCT0.06NOV0.03DEC0.761.52.33.00.04JFM0.15AMJ0.27JAS0.12OND
Gallons per square foot per month, Central Valley. Peak 0.27 in Jul, 1.71 a year.

Monthly water need by climate zone

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

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.040.040.080.080.74–
Feb0.050.070.080.090.93–
Mar0.090.110.110.131.46–
Apr0.120.150.140.161.89–
May0.150.210.160.22.39–
Jun0.160.250.170.232.85–
Jul0.160.270.20.253.04–
Aug0.150.240.190.232.79–
Sep0.120.180.150.192.14–
Oct0.090.120.110.131.46–
Nov0.050.060.080.090.93–
Dec0.030.030.070.070.65–
Year1.21.711.551.8421.27–

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 very low water in the Central Valley, like interior live oak. Plants that drink alike can share one valve and one schedule.

Oak TreesQuercus agrifoliavery low water, Central Valley0.27 gal/sq ft in JulySalt CedarTamarix aphyllavery low water, Central Valley0.27 gal/sq ft in JulyPearl AcaciaAcacia podalyriifoliavery low water, Central Valley0.27 gal/sq ft in JulyMexican Palo VerdeParkinsonia aculeatavery low water, Central Valley0.27 gal/sq ft in JulyFoothill PinePinus sabinianavery low water, Central Valley0.27 gal/sq ft in JulyBlue OakQuercus douglasiivery low water, Central Valley0.27 gal/sq ft in JulyNuttall's Scrub OakQuercus dumosavery low water, Central Valley0.27 gal/sq ft in JulyCalifornia BuckeyeAesculus californicavery low water, Central Valley0.27 gal/sq ft in JulyTree of HeavenAilanthus altissimavery low water, Central Valley0.27 gal/sq ft in JulyOleanderNerium oleander ssp. & cvs.very low water, Central Valley0.27 gal/sq ft in JulyAgaveAgave americana (and thick-leaved relatives)very low water, Central Valley0.27 gal/sq ft in JulyCactusOpuntia spp. & cvs. (CA natives and non-natives)very low water, Central Valley0.27 gal/sq ft in JulySpanish BroomSpartium junceumvery low water, Central Valley0.27 gal/sq ft in JulyBig SagebrushArtemisia tridentatavery low water, Central Valley0.27 gal/sq ft in JulyCalifornia PoppyEschscholzia californicavery low water, Central Valley0.27 gal/sq ft in JulyCalifornia Scrub OakQuercus berberidifoliavery low water, Central Valley0.27 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 interior live 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 interior live oak in summer?

In July, established interior live oak in loam needs a deep watering about once a month or less in the Central Valley, about once a month or less on the south coast and about once a month or less 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 interior live oak need per day?

In July in the Central Valley, established interior live oak needs about 0.7 gallons a day under a 10 foot canopy and about 2.7 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 interior live oak change across California?

Yes. WUCOLS rates interior live oak separately for each of the six California climate zones: very low water in the North-Central Coastal zone, very low water in the Central Valley zone, very low water in the South Coastal zone, very low water in the South Inland zone, moderate 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.

How fast does interior live oak grow?

It grows about a foot or two a year, and up to 3 feet when happy. It can reach about 50 feet. Plan for a broad crown.

Should I water an oak on drip?

Oaks do not want drip at the trunk. Water young trees with a hose or sprinkler across the root zone. Older trees in their native range need no summer water.

Can I plant interior live oak near a lawn?

Keep it about 30 to 50 feet from a lawn. Frequent summer water harms oaks. Leave the ground under the canopy dry in summer.

Should I fertilize interior live oak?

No, oaks do not like fertilizer. Avoid insecticides and fungicides near them too. Healthy soil and little water serve them best.

Where does interior live oak grow wild?

It grows in dry valleys and foothills of the Coast Ranges and Sierra Nevada. Its range runs from southern Oregon to Baja California. It is common in oak woodland.

More plant watering guides

Butterfly AgaveSisalCentury PlantBlue AgaveUtah AgaveQueen Victoria AgaveCreosote BushPurple Sage

Sources