WateringTimesWatering plan, $19
Platycladus orientalis (Thuja orientalis), WUCOLS IV

How often to water oriental arborvitae in California

In July in the Central Valley, established oriental arborvitae 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. Oriental arborvitae is a dense, slow growing evergreen conifer with scale-like leaves held in flat, upright sprays. The species forms a cone or column 18 to 25 feet tall that opens up with age. Dwarf golden cultivars stay as low as 2 or 3 feet. It tolerates most conditions except wet, boggy ground.

ShrubRated for 5 of 6 zones

How often to water oriental arborvitae, 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 oriental arborvitae 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 at the edge of the root ball signals that oriental arborvitae needs a soak
  • Foliage browning at the tips after drying wind can indicate moisture stress, especially on young plants
  • A bronze cast over the foliage in winter is normal seasonal color, not a sign of thirst
  • Fine webbing and stippled, faded foliage point to spider mites rather than a watering problem
  • Yellowing foliage and dieback in wet, boggy ground can indicate overwatering, which this plant does not tolerate

How to water it

  • Water at the drip line of oriental arborvitae with drip or a slow hose, keeping the trunk base dry
  • Soak the soil about a foot deep, then let the upper few inches dry before the next watering
  • Plant in moist but well-drained soil, never in a low, boggy spot
  • Shield young plants from drying winds and mulch the root area to slow moisture loss
  • Space plants for good air circulation and move emitters outward as each plant widens

Through the seasons

Water a new oriental arborvitae deeply through its first summer while roots spread. Established plants take deep soakings with some drying between them through the dry season. This evergreen grows slowly and holds its foliage all year, often taking on a bronze tint in winter. Winter rain usually covers the cool months on the coast and in the Central Valley, while low desert plants need checks through dry winters. WUCOLS rates oriental arborvitae moderate water on the north-central coast, in the Central Valley and on the south coast. It gives the same moderate water rating in South Inland and the low desert. WUCOLS has not evaluated it for the high desert.

In pots

Dwarf forms of oriental arborvitae, some only 2 to 3 feet tall, suit containers well. Use a pot with drainage holes and a well-drained mix that still holds some moisture. Check the mix 2 inches down every few days in summer heat, and water when it feels dry there. Let water drain out, then empty the saucer. Keep a potted plant out of drying wind, especially while it is young. In winter, water whenever the mix starts to dry.

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

Oriental Arborvitae: 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 oriental arborvitae. 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 oriental arborvitae 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 oriental arborvitae, 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 oriental arborvitae in summer?

In July, established oriental arborvitae 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 oriental arborvitae need per day?

In July in the Central Valley, established oriental arborvitae 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 oriental arborvitae change across California?

Yes. WUCOLS rates oriental arborvitae 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 evaluated 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 is my oriental arborvitae turning brown in winter?

A bronze tint in cold weather is normal for this plant. Check the soil and look for spider mites only if browning appears in the warm months. Dry, windy spells can also brown exposed tips.

Why is my arborvitae opening up in the middle?

The species naturally opens up as it ages and loses its tight conical shape. Snow or ice can also split branches apart. Neither one is a watering problem.

How big does oriental arborvitae get?

The species reaches about 18 to 25 feet tall and 10 to 15 feet wide over many years. Dwarf golden cultivars can stay 2 to 3 feet. Check the label so the watered area matches the plant's final size.

Can you overwater oriental arborvitae?

Yes. It tolerates most conditions except wet, boggy sites. Let the upper soil dry between deep soakings and keep it away from lawn sprinklers that run often.

What are the rose-shaped things on my arborvitae?

Those are its seed cones, small and grayish with hooked scales. Once they open, they look like tiny roses. They are normal and do not signal stress.

More plant watering guides

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Sources