WateringTimesWatering plan, $19
Cedrus atlantica & ssp. & cvs., WUCOLS IV

How often to water Atlas cedar in California

In July in the Central Valley, established Atlas cedar in loam needs a deep watering about every 20 days: about 55 gallons each time under a 10 foot canopy, about 19 gallons a week. Atlas cedar is a needled evergreen conifer from the Atlas Mountains of North Africa, often grown in its blue forms. It starts as a pyramid and matures into a broad, flat-topped tree 40 to 60 feet tall with wide horizontal branches. It adapts to many soils as long as they drain well, and it takes deep, widely spaced soakings.

TreeRated for 5 of 6 zones

How often to water Atlas cedar, 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 Atlas cedar 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 canopy edge of an established Atlas cedar signals that it is ready for a deep soak
  • Needles dulling and branch tips drooping during a long, hot dry spell can indicate a dry root zone
  • Some needle and branchlet drop is normal for this untidy tree and does not prove thirst
  • Yellowing needles over soil that stays soggy can indicate poor drainage, which this cedar will not tolerate
  • White, scale-like specks on the needles point to pine needle scale rather than a watering problem

How to water it

  • Water a young Atlas cedar over its root ball and the soil just beyond, widening coverage as roots spread
  • Place water for an established tree under the outer branches and beyond, away from the trunk
  • Soak slowly to a depth of 18 inches or more, then let the soil dry well before the next deep watering
  • Plant in well-drained soil, using a mound or slope where clay holds water
  • Mulch the root area with wood chips, keeping the trunk base bare

Through the seasons

Water a new Atlas cedar deeply through its first two or three summers while roots spread into native soil. Once established it copes with dry spells, taking deep soakings spaced well apart through the dry season. WUCOLS rates Atlas cedar low water on the north-central coast and in the Central Valley. It rates moderate water on the south coast, in South Inland and in the high desert. WUCOLS marks it as not suited to the low desert. Winter rain usually covers the cool months on the coast and in the Central Valley. High desert trees may need a soak in a dry winter.

In pots

Young Atlas cedars and dwarf forms can grow in a large container for a few years. The tree is difficult to transplant later, so plant it out early. Use a pot with open drainage holes and a gritty, free-draining mix. In summer heat, check the mix 2 inches down every few days and water when it is dry there. Water until excess runs out, then empty the saucer. Keep a potted cedar in full sun to light shade. In winter, water sparingly and only when the mix begins to dry.

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
0.761.52.33.00.16JAN0.26FEB0.43MAR0.61APR0.83MAY0.99JUN1.07JUL0.95AUG0.72SEP0.47OCT0.22NOV0.14DEC0.761.52.33.00.16JFM0.61AMJ1.07JAS0.47OND
Gallons per square foot per month, Central Valley. Peak 1.07 in Jul, 6.84 a year.

Monthly water need by climate zone

Atlas Cedar: gallons per square foot per month, by WUCOLS climate zone

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.150.160.780.780.74–
Feb0.210.260.810.870.93–
Mar0.350.431.151.31.46–
Apr0.470.611.41.611.89–
May0.580.831.611.952.39–
Jun0.640.991.742.292.85–
Jul0.641.071.982.513.04–
Aug0.60.951.862.332.79–
Sep0.50.721.491.862.14–
Oct0.350.471.151.331.46–
Nov0.190.220.840.90.93–
Dec0.120.140.650.680.65–
Year4.86.8415.518.4121.27–

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 low water in the Central Valley, like Atlas cedar. Plants that drink alike can share one valve and one schedule.

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 Atlas cedar, 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 Atlas cedar in summer?

In July, established Atlas cedar in loam needs a deep watering about every 20 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 Atlas cedar need per day?

In July in the Central Valley, established Atlas cedar needs about 2.7 gallons a day under a 10 foot canopy and about 11 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 Atlas cedar change across California?

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

Why is my Atlas cedar dropping needles?

Some needle and branchlet drop is normal for this tree. Heavy drop with browning branch tips during a dry summer calls for a soil check. Look for white scale on the needles as well.

Is blue Atlas cedar the same plant?

Yes. Blue Atlas cedar is a form of the same species selected for its silvery blue needles. Its water needs follow the species. Foliage across the species ranges from bright green to blue.

How big does an Atlas cedar get?

It typically reaches 40 to 60 feet tall and 30 to 40 feet wide. Young trees are pyramidal, and older trees flatten on top with broad horizontal branches. Give it plenty of space, since a crowded tree cannot develop properly.

Is Atlas cedar a fire risk?

It carries a high flammability rating. In wildfire country, plant it well away from the house. Choose lower flammability plants for the area closest to buildings.

Can Atlas cedar grow near the coast?

Yes. It is moderately salt tolerant and adapts to sandy or clay soils that drain well. Give it full sun to part shade there.

Can you overwater an Atlas cedar?

Yes. It needs good drainage, and roots in soggy ground decline. Let the soil dry well between deep soakings, and keep lawn sprinklers away from the trunk.

More plant watering guides

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Sources