WateringTimesWatering plan, $19
Quercus coccinea, WUCOLS IV

How often to water scarlet oak in California

In July in the Central Valley, established scarlet oak in loam needs a deep watering about every 8 days: about 55 gallons each time under a 10 foot canopy, about 47 gallons a week. Scarlet oak is a large, fast-growing deciduous oak from the eastern United States, reaching 50 to 80 feet with an open, rounded crown. Its glossy leaves have deep, C-shaped notches between bristle-tipped lobes and turn a long-lasting scarlet late in fall. In the wild it grows on dry, sandy uplands, and it wants acidic, well-drained soil.

TreeRated for 4 of 6 zones

How often to water scarlet 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 scarlet 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

  • Soil dry 6 inches down at the edge of the canopy in summer means a young scarlet oak needs a slow, deep soak
  • Leaves curling and crisping during a long hot spell show a young tree has run short of water
  • A white, powdery film on the leaves points to powdery mildew, not a shortage of water
  • Yellowing leaves and dying branch tips over ground that stays wet point to drainage trouble, since this oak needs well-drained soil
  • Leaves yellowing between green veins in alkaline soil point to chlorosis, which scarlet oak shows less often than pin oak

How to water it

  • Run drip rings or a soaker under the canopy and soak the soil 18 inches to 2 feet deep
  • Let the top several inches dry between soakings, since it grows wild on dry, well-drained uplands
  • Plant a small tree in acidic or neutral, well-drained soil, because the taproot makes large trees hard to move
  • Cover the root zone with wood chips instead of lawn, keeping the mulch a few inches from the trunk
  • Extend the watered ring outward as the crown spreads toward 45 to 60 feet

Through the seasons

Water a young scarlet oak deeply through its first few summers while the taproot goes down. Established trees come from dry upland forests and tolerate dry spells, but in the long California dry season they still need deep soakings. Fall color comes late and lasts, then the leaves drop for winter. During the rainy season, the bare tree usually needs no help on the coast or in the Central Valley. WUCOLS rates scarlet oak moderate water on the north-central coast, in the Central Valley, on the south coast and in South Inland. WUCOLS marks it as not suited to the high desert or the low desert.

In pots

Scarlet oak grows a deep taproot and resents transplanting, so keep it in a container only briefly. Choose a deep pot with drainage holes and a well-drained, slightly acidic mix. In warm weather, check the mix 2 inches down every few days and water when it is dry there. Let excess water drain, and do not leave the pot in a saucer. Plant it out while it is still small, before the root starts circling the pot.

1 Your climate zone six WUCOLS zones, each from its own reference city
2.67gal per sq ft in JulyModerate water use in the Central Valley zone
A year
17.11 gal per sq ft
Reference
Sacramento climate table
Counts
Plant need, before sprinkler losses
0.671.32.02.70.4JAN0.65FEB1.09MAR1.52APR2.08MAY2.48JUN2.67JUL2.39AUG1.8SEP1.18OCT0.56NOV0.34DEC0.671.32.02.70.4JFM1.52AMJ2.67JAS1.18OND
Gallons per square foot per month, Central Valley. Peak 2.67 in Jul, 17.11 a year.

Monthly water need by climate zone

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

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.370.40.780.78––
Feb0.530.650.810.87––
Mar0.871.091.151.3––
Apr1.181.521.41.61––
May1.462.081.611.95––
Jun1.612.481.742.29––
Jul1.612.671.982.51––
Aug1.492.391.862.33––
Sep1.241.81.491.86––
Oct0.871.181.151.33––
Nov0.470.560.840.9––
Dec0.310.340.650.68––
Year1217.1115.518.41––

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 moderate water in the Central Valley, like scarlet oak. Plants that drink alike can share one valve and one schedule.

Citrus TreesCitrus spp.moderate water, Central Valley2.67 gal/sq ft in JulyJapanese MapleAcer palmatummoderate water, Central Valley2.67 gal/sq ft in JulyAvocado TreesPersea americanamoderate water, Central Valley2.67 gal/sq ft in JulyMagnolia TreesMagnolia grandiflora ssp. & cvs.moderate water, Central Valley2.67 gal/sq ft in JulyPalm TreesSyagrus romanzoffiana (Arecastrum romanzoffianum)moderate water, Central Valley2.67 gal/sq ft in JulyApple TreesMalus spp. (edible) e.g, 'Anna' (low chill variety for low desert)moderate water, Central Valley2.67 gal/sq ft in JulyPeach TreesPrunus spp. ediblemoderate water, Central Valley2.67 gal/sq ft in JulyPersimmon TreesDiospyros kakimoderate water, Central Valley2.67 gal/sq ft in JulyAmur MapleAcer ginnalamoderate water, Central Valley2.67 gal/sq ft in JulyFernleaf MapleAcer japonicummoderate water, Central Valley2.67 gal/sq ft in JulyBox ElderAcer negundomoderate water, Central Valley2.67 gal/sq ft in JulyNorway MapleAcer platanoidesmoderate water, Central Valley2.67 gal/sq ft in JulyRed MapleAcer rubrummoderate water, Central Valley2.67 gal/sq ft in JulyChinese MapleAcer truncatummoderate water, Central Valley2.67 gal/sq ft in JulyRed BuckeyeAesculus paviamoderate water, Central Valley2.67 gal/sq ft in JulyRed HorsechestnutAesculus x carneamoderate water, Central Valley2.67 gal/sq ft in July

Similar plants that need less water 16

Rated lower than scarlet oak in the Central Valley. Worth a look for a new bed or a lawn replacement.

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 scarlet 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 scarlet oak in summer?

In July, established scarlet oak in loam needs a deep watering about every 8 days in the Central Valley, about every 11 days on the south coast and about every 9 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 scarlet oak need per day?

In July in the Central Valley, established scarlet oak needs about 6.8 gallons a day under a 10 foot canopy and about 27 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 scarlet oak change across California?

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

How do I tell scarlet oak from pin oak?

Look at the notches between the lobes: they are C-shaped on scarlet oak and U-shaped on pin oak. Scarlet oak acorns also sit in a deep, bowl-shaped cap, while pin oak caps are thin.

When does scarlet oak turn red?

Its leaves turn scarlet late in fall, after many other trees have colored. The color holds on the tree for a long time.

Can I transplant a scarlet oak?

Only while it is young. It grows a taproot that makes larger trees hard to move, so start with a small tree in its permanent spot.

Is scarlet oak toxic to horses?

Yes. The leaves and acorns are toxic to horses, so keep it away from pastures. Dogs can also be harmed if they eat the acorns.

How fast does scarlet oak grow?

Fast for an oak, and it is long-lived. Trees usually start bearing acorns at about 20 years, and each acorn takes two seasons to ripen.

Does scarlet oak get yellow leaves like pin oak?

Less often. It does not develop chlorosis in alkaline soil as readily as pin oak, though acidic or neutral soil still suits it best.

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Sources