WateringTimesWatering plan, $19
Pseudotsuga menziesii, WUCOLS IV

How often to water Douglas fir in California

In July in the Central Valley, established Douglas fir 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. Douglas fir is a tall evergreen conifer native from British Columbia to central California, with fragrant needles and hanging cones marked by three-pointed bracts. In gardens it often reaches 40 to 80 feet, while dwarf cultivars stay far smaller. It favors cool air and well-drained, slightly acidic soil, and it struggles with heat and warm nights.

TreeCalifornia nativeRated for 2 of 6 zones

How often to water Douglas fir, 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 Douglas fir 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 a young Douglas fir root ball signals that it needs a deep soak
  • Needles browning on the sunny side during a heat wave can indicate heat and moisture stress
  • Lower branches thinning on an older tree is part of its natural shape, not by itself a sign of thirst
  • Yellowing needles over soil that stays soggy can indicate root rot or poor drainage
  • Fine webbing and pale speckling on the needles point to spider mites rather than a watering fault

How to water it

  • Water a young Douglas fir over its root ball and the soil just beyond, widening the ring as it grows
  • Soak slowly to wet the soil 12 to 18 inches deep, then let the upper several inches dry before the next soak
  • Spread 2 to 6 inches of organic mulch over the root area, keeping it a hand's width from the trunk
  • Plant in well-drained, slightly acidic soil, and give it afternoon shade in hot inland gardens
  • Move water outward toward the canopy edge as the tree matures

Through the seasons

Give a new Douglas fir deep soakings through its first few summers while roots spread into native soil. It is evergreen and grows fast in cool, moist settings, but only slowly where summers run hot and dry. WUCOLS rates Douglas fir low water on the north-central coast and moderate water in the Central Valley. It marks the south coast, South Inland, the high desert and the low desert as not suited to it. Winter rain usually covers the cool months where it is rated, so summer is when irrigation matters. In the Central Valley, afternoon shade helps it through the heat.

In pots

Dwarf Douglas fir cultivars and young seedlings can grow in containers, while the species soon needs open ground. Use a pot with open drainage holes and a coarse, slightly acidic mix. Check the mix 2 inches down every few days in summer and water when that layer is dry. Water until excess drains, then empty the saucer. Keep the pot out of hot afternoon sun in inland areas. In winter, water only when the mix starts to dry, and never leave the roots in standing water.

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

Douglas Fir: gallons per square foot per month, by WUCOLS climate zone

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.150.4––––
Feb0.210.65––––
Mar0.351.09––––
Apr0.471.52––––
May0.582.08––––
Jun0.642.48––––
Jul0.642.67––––
Aug0.62.39––––
Sep0.51.8––––
Oct0.351.18––––
Nov0.190.56––––
Dec0.120.34––––
Year4.817.11––––

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 Douglas fir. 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 Douglas fir 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 Douglas fir, 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 much water does Douglas fir need per day?

In July in the Central Valley, established Douglas fir 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 Douglas fir change across California?

Yes. WUCOLS rates Douglas fir separately for each of the six California climate zones: low water in the North-Central Coastal zone, moderate water in the Central Valley zone, not suited to this region in the South Coastal zone, not suited to this region 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 can I recognize a Douglas fir?

Look at the cones: they hang down and carry three-pointed bracts between the scales, like small tongues. The flat needles smell fragrant when crushed and have two pale bands underneath. Young trees are narrow pyramids that lose their lower branches with age.

Will Douglas fir grow in Southern California?

It is a poor choice for most of Southern California. It dislikes heat, humidity and warm nights, and it grows best in cool northern gardens near the coast or at elevation. Where summers are hot, give it afternoon shade.

How much mulch does a Douglas fir need?

A layer of 2 to 6 inches of organic mulch over the root area keeps the soil cool and moist. Keep it pulled back from the trunk. Leave fallen needles in place as part of that layer.

Can you overwater a Douglas fir?

Yes. It needs well-drained soil, and root rot can follow in ground that stays wet. Water deeply, then let the upper soil dry before the next soak. Avoid planting it in a frequently watered lawn.

How big does Douglas fir get in a garden?

Garden trees typically reach 40 to 80 feet, far short of the giants in native forests. Dwarf cultivars stay small enough for borders and large pots. Growth is fast in cool, moist conditions and slow where summers are hot.

More plant watering guides

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Sources