WateringTimesWatering plan, $19
Ailanthus altissima, WUCOLS IV

How often to water tree of heaven in California

In July in the Central Valley, established tree of heaven in loam needs a deep soak only about once a month or less: about 55 gallons each time under a 10 foot canopy. Tree of heaven is a fast growing deciduous tree with long, aromatic compound leaves and sprays of pale yellow flowers followed by winged seeds. It spreads aggressively by root suckers and self-sown seed, forming dense colonies that crowd out other plants. The California Invasive Plant Council lists it as invasive, and landscape use is discouraged.

TreeRated for 5 of 6 zones

How often to water tree of heaven, 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 tree of heaven 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

  • A young tree with leaves wilting by afternoon over bone dry soil may need an occasional soak while it establishes
  • Check soil beneath an existing tree of heaven before irrigating, since its regional water needs are low or very low
  • New suckers rising well beyond the original trunk reflect this tree's spreading habit rather than a watering problem
  • Saturated soil around tree of heaven after nearby lawn watering is a reason to check for unnecessary irrigation
  • Leaf scorch during a long dry heat wave on a young planting can point to a dry root ball

How to water it

  • Base watering of an existing tree of heaven on soil moisture and its low or very low regional rating
  • Avoid watering an unwanted tree of heaven as a way to manage its root suckers
  • Check surrounding irrigation for leaks where soil stays saturated beside a tree of heaven
  • Pull small tree of heaven seedlings before creeping roots develop, and seek help with established suckering stands
  • Choose a different, non-suckering species for new plantings rather than expanding an existing stand

Through the seasons

Tree of heaven loses its leaves for winter, and existing trees have low or very low regional water needs. During the first dry season, inspect a retained young tree's root ball before deciding whether water is needed. Avoid nurturing unwanted seedlings or suckers. Coastal and valley winter rain can reduce irrigation, but check actual soil moisture instead of assuming that every inland site stays dry. WUCOLS rates tree of heaven very low water on the north-central coast and in the Central Valley. It rates low water in South Inland, the high desert and the low desert. WUCOLS marks it as not suited to the south coast.

In pots

Do not cultivate tree of heaven in a patio container; its invasive spread makes another species a better choice. Pull a small seedling from a pot before it develops creeping roots. Inspect nearby containers after a seed-bearing tree releases its winged fruits. During California heat, keep watering the intended container plant according to its own needs. Continue checking for tree of heaven seedlings after winter rain, and seek removal advice for shoots connected to an established root system.

1 Your climate zone six WUCOLS zones, each from its own reference city
0.27gal per sq ft in JulyVery low water use in the Central Valley zone
A year
1.71 gal per sq ft
Reference
Sacramento climate table
Counts
Plant need, before sprinkler losses
0.300.610.921.20.04JAN0.07FEB0.11MAR0.15APR0.21MAY0.25JUN0.27JUL0.24AUG0.18SEP0.12OCT0.06NOV0.03DEC0.300.610.921.20.04JFM0.15AMJ0.27JAS0.12OND
Gallons per square foot per month, Central Valley. Peak 0.27 in Jul, 1.71 a year.

Monthly water need by climate zone

Tree of Heaven: gallons per square foot per month, by WUCOLS climate zone

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.040.04–0.310.30.31
Feb0.050.07–0.350.370.37
Mar0.090.11–0.520.580.61
Apr0.120.15–0.640.760.78
May0.150.21–0.780.950.98
Jun0.160.25–0.921.141.12
Jul0.160.27–11.221.14
Aug0.150.24–0.931.121.04
Sep0.120.18–0.740.860.83
Oct0.090.12–0.530.580.6
Nov0.050.06–0.360.370.38
Dec0.030.03–0.270.260.27
Year1.21.71–7.378.518.43

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 very low water in the Central Valley, like tree of heaven. Plants that drink alike can share one valve and one schedule.

Oak TreesQuercus agrifoliavery low water, Central Valley0.27 gal/sq ft in JulySalt CedarTamarix aphyllavery low water, Central Valley0.27 gal/sq ft in JulyPearl AcaciaAcacia podalyriifoliavery low water, Central Valley0.27 gal/sq ft in JulyMexican Palo VerdeParkinsonia aculeatavery low water, Central Valley0.27 gal/sq ft in JulyFoothill PinePinus sabinianavery low water, Central Valley0.27 gal/sq ft in JulyInterior Live OakQuercus wislizenivery low water, Central Valley0.27 gal/sq ft in JulyBlue OakQuercus douglasiivery low water, Central Valley0.27 gal/sq ft in JulyNuttall's Scrub OakQuercus dumosavery low water, Central Valley0.27 gal/sq ft in JulyCalifornia BuckeyeAesculus californicavery low water, Central Valley0.27 gal/sq ft in JulyOleanderNerium oleander ssp. & cvs.very low water, Central Valley0.27 gal/sq ft in JulyAgaveAgave americana (and thick-leaved relatives)very low water, Central Valley0.27 gal/sq ft in JulyCactusOpuntia spp. & cvs. (CA natives and non-natives)very low water, Central Valley0.27 gal/sq ft in JulySpanish BroomSpartium junceumvery low water, Central Valley0.27 gal/sq ft in JulyBig SagebrushArtemisia tridentatavery low water, Central Valley0.27 gal/sq ft in JulyCalifornia Scrub OakQuercus berberidifoliavery low water, Central Valley0.27 gal/sq ft in JulyCreosote BushLarrea tridentata ssp. & cvs.very low water, Central Valley0.27 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 tree of heaven, 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 tree of heaven in summer?

In July, established tree of heaven in loam needs a deep watering about once a month or less in the Central Valley 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 tree of heaven need per day?

In July in the Central Valley, established tree of heaven needs about 0.7 gallons a day under a 10 foot canopy and about 2.7 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 tree of heaven change across California?

Yes. WUCOLS rates tree of heaven separately for each of the six California climate zones: very low water in the North-Central Coastal zone, very low water in the Central Valley zone, not suited to this region in the South Coastal zone, low water in the South Inland zone, low water in the High and Intermediate Desert zone, low water 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 tree of heaven considered a problem tree?

Tree of heaven can form dense colonies from spreading roots and seed, displacing other vegetation. Cal-IPC lists it as invasive, and its use in urban landscapes is discouraged. Plan control of an existing stand rather than encouraging new trees.

How do I stop tree of heaven from spreading on my property?

Cutting alone can produce stump sprouts and additional root suckers. Hand pulling works for small seedlings before creeping roots develop, but generally fails on an established root system. Get professional advice for removing a mature stand and managing regrowth.

Does tree of heaven need irrigation once it is established?

Its WUCOLS ratings indicate low or very low water needs wherever it is rated as suitable. Check the soil before irrigating an existing tree, and do not water unwanted seedlings to help them establish. The ratings do not establish that mature trees never need supplemental water.

Why does my yard keep getting new tree of heaven seedlings?

Female trees produce winged fruits that disperse on wind and water. Remove small seedlings before their spreading roots become established. Continue checking while a nearby seed source remains; a few seasons of pulling do not guarantee that new seedlings will stop.

Is tree of heaven related to the spread of pest insects?

Tree of heaven is a preferred host of the invasive spotted lanternfly. That association reinforces the reasons to avoid planting it. Removing an established tree still requires a plan for its persistent roots and regrowth.

More plant watering guides

Fox Tail AgaveSaltbushParry's AgaveOleanderAgaveCactusOak TreesSpanish Broom

Sources