WateringTimesWatering plan, $19
Aucuba japonica (SHADE), WUCOLS IV

How often to water Japanese aucuba in California

In July in the Central Valley, established Japanese aucuba in loam needs a deep watering about every 8 days: about 8.8 gallons each time for a plant 4 feet across, about 7.6 gallons a week. Japanese aucuba is a broadleaf evergreen shrub with glossy, leathery leaves, often variegated in garden forms. It is grown in partial to deep shade, since sun blackens its young leaves. It needs moist soil with good drainage, because roots kept soggy are prone to rot.

ShrubRated for 5 of 6 zones

How often to water Japanese aucuba, month by month

Your city
Plant width
4 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 Japanese aucuba 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 the plant covers, 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 plant width

A shrub with its width marked from one side to the other and the circle under it shaded blue

Measure across the plant, from the tips of the leaves on one side to the tips on the other.

Water the whole area the plant covers, shown in blue. The gallons here cover that area.

A wider plant means more gallons each watering, not more waterings. While it is young, measure again each spring.

How to tell it needs water

  • Soil dry 3 to 4 inches down beneath the outer leaves signals that Japanese aucuba needs water
  • Leaves that droop and stay soft into the morning over dry soil can indicate thirst
  • Blackened patches on young leaves usually mean too much sun rather than too little water
  • Leaves yellowing and dropping while the soil stays wet can point to root rot
  • Sticky leaves or white cottony tufts point to scale or mealybugs, a pest problem rather than a watering one

How to water it

  • Water Japanese aucuba at the base with drip or a soaker beneath the leaves
  • Soak the root zone about 12 inches deep, then let the top couple of inches dry before the next soak
  • Plant it in shade in soil that drains well, raising the bed where clay holds water
  • Mulch with shredded bark or leaf mold to keep the soil cool, leaving the stems clear
  • Extend the drip line outward as the shrub widens toward its mature 4 to 6 foot spread

Through the seasons

Water a new Japanese aucuba often enough to keep its root ball moist through the first summer, then shift to deeper, spaced soakings. Established shrubs stay evergreen all year, so they keep drawing some water in winter. Red berries on female plants color in fall and can hang on until spring. Irrigation matters most from late spring through early fall. Winter rain covers the cool months on the coast and in the Central Valley in most years. WUCOLS rates Japanese aucuba moderate water on the north-central coast, in the Central Valley and on the south coast. It also rates moderate water in South Inland and in the low desert. WUCOLS marks it as not suited to the high desert.

In pots

Japanese aucuba is a reliable shade container shrub, and its glossy leaves suit a covered patio. Use a pot with drainage holes and a mix rich in organic matter. Check the top 2 inches every few days in summer heat, and water when that layer is dry. Let water run out of the holes, then empty the saucer, since standing water invites root rot. Keep the pot out of afternoon sun. In winter, water less often and make sure rain has not left the mix soggy.

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
0.711.42.12.90.4JAN0.65FEB1.09MAR1.52APR2.08MAY2.48JUN2.67JUL2.39AUG1.8SEP1.18OCT0.56NOV0.34DEC0.711.42.12.90.4JFM1.52AMJ2.67JAS1.18OND
Gallons per square foot per month, Central Valley. Peak 2.67 in Jul, 17.11 a year.

Monthly water need by climate zone

Japanese Aucuba: gallons per square foot per month, by WUCOLS climate zone

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.370.40.780.78–0.78
Feb0.530.650.810.87–0.93
Mar0.871.091.151.3–1.52
Apr1.181.521.41.61–1.95
May1.462.081.611.95–2.45
Jun1.612.481.742.29–2.79
Jul1.612.671.982.51–2.85
Aug1.492.391.862.33–2.6
Sep1.241.81.491.86–2.08
Oct0.871.181.151.33–1.49
Nov0.470.560.840.9–0.96
Dec0.310.340.650.68–0.68
Year1217.1115.518.41–21.08

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

RosesRosa hybrids..bushmoderate water, Central Valley2.67 gal/sq ft in JulyAzaleasRhododendron spp. (CA native and non-native spp.)moderate water, Central Valley2.67 gal/sq ft in JulyCamelliasCamellia japonica (SHADE IN DESERT)moderate water, Central Valley2.67 gal/sq ft in JulyGardeniasGardenia spp. & cvs.moderate water, Central Valley2.67 gal/sq ft in JulyBird of ParadiseStrelitzia reginae (shade in desert)moderate water, Central Valley2.67 gal/sq ft in JulyHibiscusHibiscus rosa-sinensismoderate water, Central Valley2.67 gal/sq ft in JulySago PalmCycas revolutamoderate water, Central Valley2.67 gal/sq ft in JulyStar JasmineTrachelospermum jasminoides and cvs.moderate water, Central Valley2.67 gal/sq ft in JulyArborvitaeThuja occidentalis ssp. & cvs.moderate water, Central Valley2.67 gal/sq ft in JulyBambooBambusa spp.moderate water, Central Valley2.67 gal/sq ft in JulyLilacsSyringa hybrids (including Descanso hybrids)moderate water, Central Valley2.67 gal/sq ft in JulySpireaSpiraea spp. (CA native and non native spp.)moderate water, Central Valley2.67 gal/sq ft in JulyButterfly BushBuddleja davidii and hybridsmoderate water, Central Valley2.67 gal/sq ft in JulySageSalvia officinalis and cvs.moderate water, Central Valley2.67 gal/sq ft in JulyRed BuckeyeAesculus paviamoderate water, Central Valley2.67 gal/sq ft in JulyWestern ServiceberryAmelanchier alnifoliamoderate water, Central Valley2.67 gal/sq ft in July

Similar plants that need less water 16

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

LavenderLavandula spp. & cvs.low water, Central Valley1.07 gal/sq ft in JulyRosemaryRosmarinus officinalislow water, Central Valley1.07 gal/sq ft in JulyBougainvilleaBougainvillea & spp. & cvs.low water, Central Valley1.07 gal/sq ft in JulyOlive TreesOlea europaea 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 JulyLantanaLantana camara ssp. & cvs.low water, Central Valley1.07 gal/sq ft in JulySalviaSalvia greggii ssp., cvs. & hybridslow water, Central Valley1.07 gal/sq ft in JulyAloeAloe spp. & cvs.low water, Central Valley1.07 gal/sq ft in JulySucculentsEcheveria spp. & cvs.low water, Central Valley1.07 gal/sq ft in JulyJunipersJuniperus spp. & cvs.low water, Central Valley1.07 gal/sq ft in JulyRussian SagePerovskia spp. & cvs.low water, Central Valley1.07 gal/sq ft in JulySagebrushArtemisia spp. (shrubby)low water, Central Valley1.07 gal/sq ft in JulyWild PrivetLigustrum vulgarelow water, Central Valley1.07 gal/sq ft in JulyCoralberrySymphoricarpos orbiculatus (SHADE)low water, Central Valley1.07 gal/sq ft in JulySydney Golden WattleAcacia longifolialow water, Central Valley1.07 gal/sq ft in JulyBlue Leaf WattleAcacia salignalow 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 Japanese aucuba, 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 Japanese aucuba in summer?

In July, established Japanese aucuba 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 Japanese aucuba need per day?

In July in the Central Valley, established Japanese aucuba needs about 1.1 gallons a day for a plant 4 feet across and about 4.3 gallons a day for a plant 8 feet across. Give it in deep waterings spread days apart rather than a little every day, so the whole root zone gets wet.

Does watering for Japanese aucuba change across California?

Yes. WUCOLS rates Japanese aucuba 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, 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.

Why are my aucuba leaves turning black?

Young leaves blacken when they get direct sun, especially in the afternoon. Move a potted plant into shade or give a planted one more cover. Check the soil too, since root rot also troubles aucuba in soggy ground.

Why doesn't my Japanese aucuba have berries?

Aucuba has separate male and female plants, and only females carry the red berries. A female needs a male plant nearby to set fruit. Watering does not change this.

Can Japanese aucuba grow in full sun?

Not well. Young leaves blacken in direct sun, and hot sun dries the soil faster. Grow it in partial to deep shade.

Can you overwater Japanese aucuba?

Yes. It likes moist soil but needs good drainage, and root rot is one of its main problems. Let the top couple of inches dry before soaking again.

Does wind bother Japanese aucuba?

Yes. Drying wind can burn its leaves, much as sun does. A sheltered, shaded spot holds soil moisture longer and protects the foliage.

How do I water aucuba under trees?

Tree roots compete for water in the shade aucuba prefers, and a dense canopy can block rain. Check the soil under the shrub itself. Give it its own drip line rather than relying on lawn watering.

More plant watering guides

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Sources