How often to water mountain white gum in California
In July on the north-central coast, established mountain white gum in loam needs a deep soak only about once a month or less: about 55 gallons each time under a 10 foot canopy. Mountain white gum is a fast-growing evergreen eucalyptus from Australia, with white and gray bark that flakes away. New leaves are coppery, and mature leaves hang long, narrow and dark gray-green. It grows well over 40 feet tall. Once rooted, it wants infrequent, deep soakings rather than the frequent shallow watering a lawn gets.
How often to water mountain white gum, month by month
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.
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.
How to tell it needs water
- Soil dry 6 inches down at the edge of a young tree's root ball, during its first summers, means it needs a deep soak
- Wilted, limp new shoots on a young tree during a heat wave, over dry soil, point to a thirsty root zone
- Holes in the bark with stains or oozing liquid, plus wilting leaves, point to longhorned borers drawn to a stressed tree
- Thinning, yellowing leaves while the soil around the trunk stays wet for days point to root rot from waterlogging
- Bark peeling away in white and gray patches is normal for this tree and is not a sign of thirst
How to water it
- Water a young tree slowly over its root ball and a ring beyond it, then widen the ring as the tree grows
- Apply water slowly until it reaches a foot or more down, then let the soil dry well before the next soak
- Set drip emitters under the outer edge of an older tree's canopy rather than close to the trunk
- Keep a circle about 3 feet wide around a young trunk free of turf and weeds, with mulch held a few inches off the bark
- Plant in well-drained soil in full sun, well away from buildings, since it dislikes being moved once settled
Through the seasons
Plant in spring so roots can settle before winter. Water a young tree during dry spells for its first few years, until it is well rooted. An established tree wants infrequent, deep soakings in long dry summers, applied under the outer canopy. If a tree has been watered regularly, do not stop suddenly in summer, since that stress invites borers. The tree stays evergreen all year. WUCOLS rates mountain white gum low water on the north-central coast, where winter rain covers the cool months. WUCOLS marks it as not suited to the Central Valley. WUCOLS has not evaluated it for the south coast, South Inland, the high desert or the low desert.
In pots
Mountain white gum outgrows any container, so a pot is only a short stop before planting. Smaller trees, up to about 3 feet tall, settle into the ground best, so plant it out early. Check the nursery can 2 inches down every few days in summer, and daily in a hot spell. Water until it drains from the holes, then empty the saucer. Eucalyptus dislike root disturbance, so handle the root ball gently. Over winter, raise the pot on feet so the drainage holes stay clear.
- A year
- no figure
- Reference
- Sacramento climate table
- Counts
- Plant need, before sprinkler losses
WUCOLS lists Mountain White Gum as not suited to this region for the Central Valley zone, so no monthly figure is computed here.
Monthly water need by climate zone
Mountain White Gum: gallons per square foot per month, by WUCOLS climate zone
| Month | N. Coast | C. Valley | S. Coast | S. Inland | Hi Desert | Lo Desert |
|---|---|---|---|---|---|---|
| Jan | 0.15 | – | – | – | – | – |
| Feb | 0.21 | – | – | – | – | – |
| Mar | 0.35 | – | – | – | – | – |
| Apr | 0.47 | – | – | – | – | – |
| May | 0.58 | – | – | – | – | – |
| Jun | 0.64 | – | – | – | – | – |
| Jul | 0.64 | – | – | – | – | – |
| Aug | 0.6 | – | – | – | – | – |
| Sep | 0.5 | – | – | – | – | – |
| Oct | 0.35 | – | – | – | – | – |
| Nov | 0.19 | – | – | – | – | – |
| Dec | 0.12 | – | – | – | – | – |
| Year | 4.8 | – | – | – | – | – |
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 not suited to this region in the Central Valley, like mountain white gum. Plants that drink alike can share one valve and one schedule.
Sugar MapleAcer saccharumnot rated, Central Valleyno Central Valley rating
Queensland KauriAgathis robustanot rated, Central Valleyno Central Valley rating
CherimoyaAnnona cherimolanot rated, Central Valleyno Central Valley rating
Purple Orchid TreeBauhinia variegata (purpurea)not rated, Central Valleyno Central Valley rating
ToogBischofia javanicanot rated, Central Valleyno Central Valley rating
Clustered Fishtail PalmCaryota mitisnot rated, Central Valleyno Central Valley rating
White SapoteCasimiroa edulisnot rated, Central Valleyno Central Valley rating
FilbertCorylus maximanot rated, Central Valleyno Central Valley rating
Spotted GumCorymbia maculata (Eucalyptus maculata)not rated, Central Valleyno Central Valley rating
Dove TreeDavidia involucratanot rated, Central Valleyno Central Valley rating
Royal PoincianaDelonix regianot rated, Central Valleyno Central Valley rating
Triangle PalmDypsis decaryinot rated, Central Valleyno Central Valley rating
Rainbow EucalyptusEucalyptus degluptanot rated, Central Valleyno Central Valley rating
Roxburgh FigFicus auriculatanot rated, Central Valleyno Central Valley rating
Indian BanyanFicus benghalensisnot rated, Central Valleyno Central Valley rating
Weeping Chinese BanyanFicus benjaminanot rated, Central Valleyno Central Valley ratingTurn this into minutes on your water days
Every city page has a calculator that takes mountain white 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 much water does mountain white gum need per day?
In July on the north-central coast, established mountain white gum needs about 1.6 gallons a day under a 10 foot canopy and about 6.5 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 mountain white gum change across California?
Yes. WUCOLS rates mountain white gum separately for each of the six California climate zones: low water in the North-Central Coastal zone, not suited to this region in the Central Valley zone, not evaluated in the South Coastal zone, not evaluated in the South Inland zone, not evaluated in the High and Intermediate Desert zone, not evaluated in the Low Desert zone. The monthly table above shows how the same rating translates into different gallon amounts as reference evapotranspiration changes.
Can mountain white gum grow in a lawn?
It can, but lawn watering does not suit it. Frequent, shallow watering of the kind turf gets can promote root disease in eucalyptus. Keep sprinkler spray off the trunk and give the tree its own slow, deep soak in long dry spells.
Does mountain white gum get borers?
It is listed among the eucalyptus more resistant to the eucalyptus longhorned borer. Any eucalyptus can still be attacked when it is badly stressed, for example by drought or poor soil. Steady deep watering through dry summers is the best defense.
When should I prune mountain white gum?
Prune in December or January, when adult borer beetles are not active. Spread heavy limb removal over several years. Bark suddenly exposed to full sun can burn, and the damaged bark invites borers.
Is the peeling bark on my mountain white gum a problem?
No. Flaking white and gray bark is a feature of this species. Holes, dark stains or oozing liquid on the trunk are different, and point to borers.
How close to a house can I plant mountain white gum?
Give it plenty of room. It grows more than 40 feet tall and roughly 13 to 26 feet wide. Large eucalyptus can dry out the soil near buildings, especially heavy clay, and they dislike being moved once settled.
Why do young mountain white gum leaves look different?
Like most eucalyptus, it has juvenile and adult leaves. Juvenile leaves are oval and gray-green, while adult leaves are long, narrow and drooping. The change is normal and has nothing to do with watering.
More plant watering guides
Sources
- WUCOLS IV plant water use classification for Eucalyptus dalrympleana, the University of California survey California agencies use for landscape plan reviewRead August 23, 2026 on wucols.ucdavis.edu
- Model Water Efficient Landscape Ordinance, adopted text and appendices, effective 2025-01-02 · monthly reference evapotranspiration per city, Appendix CRead August 23, 2026 on water.ca.gov/-/media/DWR-Website/Web-Pages/Programs/Water-Use-And-Efficiency/MWELO-Rulemaking/Final-MWELO-Text-and-Appendices_20250103.pdf
- UC Statewide IPM Program, irrigation scheduling using evapotranspirationRead September 30, 2026 on ipm.ucanr.edu/PMG/GARDEN/ENVIRON/evap.html
- Shaw and Pittenger, Landscape Irrigation System Evaluation and Management, UC Cooperative Extension, 2009Read September 30, 2026 on ucanr.edu/sites/default/files/2013-02/160836.pdf
- Pittenger, Water Management in Gardens and Landscapes, UC Riverside, 2017Read September 30, 2026 on ucanr.edu/sites/default/files/2017-03/258022.pdf