WateringTimesWatering plan, $19
Eucalyptus polyanthemos, WUCOLS IV

How often to water eucalyptus in California

In July in the Central Valley, established eucalyptus 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. Silver dollar gum is a fast-growing evergreen eucalyptus with round, blue-gray juvenile leaves. Its spreading roots need deep watering during establishment, then time for the soil to dry between soakings. Constant moisture against the trunk can damage the crown, especially in heavy ground.

TreeRated for 6 of 6 zones

How often to water eucalyptus, 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 eucalyptus 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

  • Dry soil near the canopy edge calls for checking deeper moisture before watering an established silver dollar gum
  • Limp, dull leaves over dry soil can indicate thirst in a young gum
  • Inner leaf drop with brittle twig tips after prolonged dryness can accompany water stress
  • Yellowing leaves or dark bark near the crown over soggy ground warrant a drainage check

How to water it

  • Water near the canopy edge and beyond it, keeping the trunk and root crown dry
  • Soak slowly to wet soil a foot or more down, then let the root zone dry between applications
  • Use a wide ring of drip emitters or a soaker loop and keep sprinkler spray off the gum bark
  • Spread coarse wood chips beneath the canopy, leaving the trunk clear of mulch
  • Plant slightly high in heavy clay, keep lawn irrigation away, and expand coverage as the gum grows

Through the seasons

Keep a new gum root ball moist through its first summer, expanding the watered area as roots move into surrounding soil. Established trees can take deep, widely spaced soakings. Silver dollar gum stays evergreen and uses some water through winter. Coastal and Central Valley rain can supply the cool months, with irrigation chiefly needed from late spring into fall. Check desert trees through dry winter gaps as well as summer. WUCOLS rates this eucalyptus low water on the north-central coast, in the Central Valley, on the south coast and in South Inland. It rates moderate water in the high desert and the low desert.

In pots

Silver dollar gum grows quickly and can soon fill a container with roots. Check the top couple of inches of mix often in California summer heat, especially when wind dries the leafy young tree. Water when that layer is dry, letting excess escape through the drainage holes. Empty the saucer so roots do not remain submerged. Reduce irrigation in winter and let the mix dry between soakings. Plan more root space before the tree becomes crowded.

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

Eucalyptus: gallons per square foot per month, by WUCOLS climate zone

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.150.160.310.310.740.78
Feb0.210.260.320.350.930.93
Mar0.350.430.460.521.461.52
Apr0.470.610.560.641.891.95
May0.580.830.640.782.392.45
Jun0.640.990.690.922.852.79
Jul0.641.070.7913.042.85
Aug0.60.950.740.932.792.6
Sep0.50.720.60.742.142.08
Oct0.350.470.460.531.461.49
Nov0.190.220.330.360.930.96
Dec0.120.140.260.270.650.68
Year4.86.846.27.3721.2721.08

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 eucalyptus. 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 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 JulyBlackwood AcaciaAcacia melanoxylonlow 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 eucalyptus, 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 eucalyptus in summer?

In July, established eucalyptus 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 eucalyptus need per day?

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

Yes. WUCOLS rates eucalyptus 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, moderate 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.

How do I water a newly planted eucalyptus?

Check the nursery mix itself, which can dry faster than the surrounding ground. Soak the root ball and widen the wet area as roots extend. Avoid keeping irrigation at a single point beside the trunk.

Can you overwater eucalyptus?

Yes. If the crown softens in wet soil, stop irrigating and clear damp mulch away from the trunk base. Redirect water draining toward the tree before resuming irrigation.

Can I keep eucalyptus indoors?

Silver dollar gum needs full sun and moving air, so an indoor stay is best kept temporary. Stretching toward a window and shedding leaves can reflect poor light. More water does not solve that problem.

Does this advice cover every garden eucalyptus?

The ratings here belong to silver dollar gum. Do not assume they describe every other gum sold for foliage. Young, potted or heavily cut-back plants also need closer moisture checks than established landscape trees.

When should I change water for cut eucalyptus?

Replace vase water when it clouds and recut the stem ends. Remove leaves below the waterline and keep the vase away from direct sun. Stems hung in a shower are left to dry and need no vase water.

More plant watering guides

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Sources