WateringTimesWatering plan, $19
Berberis aquifolium (Mahonia), WUCOLS IV

How often to water Oregon grape in California

In July in the Central Valley, established Oregon grape in loam needs a deep watering about every 20 days: about 8.8 gallons each time for a plant 4 feet across, about 3.0 gallons a week. Oregon grape is an evergreen shrub of the barberry family, native to the western United States from Oregon to central Mexico, where it grows under forest trees. It reaches 3 to 6 feet with glossy, spiny, holly-like leaves that turn purplish bronze in winter. Fragrant yellow flowers in early spring give way to grape-like clusters of dark blue fruit.

ShrubCalifornia nativeRated for 6 of 6 zones

How often to water Oregon grape, 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 Oregon grape 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 6 inches down under the shrub in summer means Oregon grape can take a deep drink
  • Leaf color bleaching on a sunny site points to too much sun, not too little water
  • Leaves browning at the edges in summer heat can follow dry soil and hot sun
  • Leaves turning purplish bronze in winter is normal color, not stress

How to water it

  • Water deeply, then let the soil dry well between soakings
  • Give established plants only occasional summer water
  • Plant in light shade with a few hours of sun for flowers
  • Use it in small groups in shade or woodland plantings
  • Prune after flowering, since next year's flowers form on old growth

Through the seasons

Water new plants through their first summer while roots grow. Once established, it is drought tolerant and slow growing, and it may sucker into small colonies. It dislikes summer heat, so shade matters more inland. Flowers open in early spring, and fruit can hang into winter. WUCOLS rates Oregon grape low water on the north-central coast, in the Central Valley, on the south coast, in South Inland and in the high desert. In the low desert it carries a moderate water rating.

In pots

Oregon grape can grow in a large container in light shade. Use a well-drained mix with some compost. Water when the top few inches dry, letting it drain fully. In summer, a pot needs checking every few days. Empty the saucer. Keep the pot out of hot afternoon sun, which bleaches the leaves. In winter, rain usually covers it, so check before watering.

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
0.711.42.12.90.16JAN0.26FEB0.43MAR0.61APR0.83MAY0.99JUN1.07JUL0.95AUG0.72SEP0.47OCT0.22NOV0.14DEC0.711.42.12.90.16JFM0.61AMJ1.07JAS0.47OND
Gallons per square foot per month, Central Valley. Peak 1.07 in Jul, 6.84 a year.

Monthly water need by climate zone

Oregon Grape: gallons per square foot per month, by WUCOLS climate zone

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.150.160.310.310.30.78
Feb0.210.260.320.350.370.93
Mar0.350.430.460.520.581.52
Apr0.470.610.560.640.761.95
May0.580.830.640.780.952.45
Jun0.640.990.690.921.142.79
Jul0.641.070.7911.222.85
Aug0.60.950.740.931.122.6
Sep0.50.720.60.740.862.08
Oct0.350.470.460.530.581.49
Nov0.190.220.330.360.370.96
Dec0.120.140.260.270.260.68
Year4.86.846.27.378.5121.08

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 Oregon grape. Plants that drink alike can share one valve and one schedule.

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 Oregon grape, 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 Oregon grape in summer?

In July, established Oregon grape 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 Oregon grape need per day?

In July in the Central Valley, established Oregon grape needs about 0.4 gallons a day for a plant 4 feet across and about 1.7 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 Oregon grape change across California?

Yes. WUCOLS rates Oregon grape 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, low 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.

Is Oregon grape fruit edible?

The plant has low severity poison characteristics, so treat the fruit as ornamental. The clusters can hang into winter. Keep children from eating them.

Can Oregon grape grow in full sun?

It grows best in light shade, since full sun bleaches the leaf color. It needs a few hours of sun to flower. Inland, shade is important.

Why does Oregon grape spread?

It tends to sucker and form colonies over time. Cut out stray shoots if needed. It spreads slowly.

When should I prune Oregon grape?

Prune soon after flowering. Next season's flowers and fruit form on old growth. It can be pruned to size.

Why are my Oregon grape leaves purple?

The leaves turn purplish bronze in winter. That is normal. Green returns with new growth.

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Sources