WateringTimesWatering plan, $19
Eucalyptus viminalis, WUCOLS IV

How often to water manna gum in California

In July in the Central Valley, established manna gum 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. Manna gum is a fast-growing evergreen eucalyptus from southeastern Australia that reaches 30 to 90 feet. Its rough, dark lower bark peels away in long ribbons, while the upper trunk stays pale and smooth. Its narrow leaves are aromatic, and white-stamened flowers bloom in summer. It is among the eucalyptus more susceptible to longhorned borers.

TreeRated for 5 of 6 zones

How often to water manna gum, 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 manna gum 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

  • Deep soil dry around a young manna gum in its first summers means a slow, deep watering is due
  • Leaves wilting and thinning in the crown during a long drought can signal water stress
  • Oozing sap, holes or dying limbs point to borers, which target drought-stressed trees
  • Yellowing leaves in waterlogged ground point to too much water

How to water it

  • Water infrequently but deeply, so moisture soaks a foot or more down
  • Run drip emitters slowly so water soaks in
  • Keep watering steady through summer once a routine is set
  • Plant in full sun in well-drained soil with room for a very large tree
  • Do not stack fresh-cut eucalyptus wood near living trees

Through the seasons

Water a young tree regularly through its first summers. After that, it needs deep, infrequent soaks in dry periods, with more in South Inland and the low desert. Because manna gum is more susceptible to longhorned borers, avoid long gaps or sudden stops in watering during hot summers. It flowers in summer. WUCOLS rates manna gum low water on the north-central coast, in the Central Valley and on the south coast. In South Inland and the low desert it carries a moderate water rating. WUCOLS marks it as not suited to the high desert.

In pots

Manna gum grows far too large for a container beyond its first season or two, so treat a pot as a short nursery stage. A young tree can wait in a deep pot of well-drained mix. Water when the top few inches dry, soaking until it drains out the base. Check every few days in summer. Keep the saucer empty. Plant it out early, in a spot with room for a very big tree.

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

Manna Gum: gallons per square foot per month, by WUCOLS climate zone

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.150.160.310.78–0.78
Feb0.210.260.320.87–0.93
Mar0.350.430.461.3–1.52
Apr0.470.610.561.61–1.95
May0.580.830.641.95–2.45
Jun0.640.990.692.29–2.79
Jul0.641.070.792.51–2.85
Aug0.60.950.742.33–2.6
Sep0.50.720.61.86–2.08
Oct0.350.470.461.33–1.49
Nov0.190.220.330.9–0.96
Dec0.120.140.260.68–0.68
Year4.86.846.218.41–21.08

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 low water in the Central Valley, like manna gum. 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 manna gum, 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 manna gum in summer?

In July, established manna gum 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 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 manna gum need per day?

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

Yes. WUCOLS rates manna gum 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, moderate water in the South Inland zone, not suited to this region 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 manna gum prone to borers?

Yes, it is rated more susceptible to the eucalyptus longhorned borer. Borers favor drought-stressed trees. Deep, steady watering in dry spells helps.

How big does manna gum get?

It grows fast to 30 to 90 feet tall and 25 to 50 feet wide. It is a tree for large spaces. Plant it well away from buildings.

Why does manna gum shed bark in strips?

Rough lower bark sheds in long strips, revealing smooth creamy white or pale gray bark above. It is normal. The strips can be raked up.

When does manna gum bloom?

It blooms in summer with white-stamened flowers. Woody seed capsules follow. Flowers sit in small clusters.

How should I water a large eucalyptus?

Apply water slowly, so it soaks a foot or more deep. Water infrequently rather than lightly and often. Avoid sudden cutoffs in summer.

More plant watering guides

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Sources