WateringTimesWatering plan, $19
Yucca brevifolia, WUCOLS IV

How often to water Joshua tree in California

In July on the north-central coast, established Joshua tree in loam needs a deep soak only about once a month or less: about 8.8 gallons each time for a plant 4 feet across. Joshua tree is a slow-growing tree yucca of the Mojave Desert, with stiff, sharp-tipped leaves clustered at the ends of its branches. A garden plant stays small for many years, and wild trees can live well over a century. It needs full sun, perfect drainage and little or no summer water.

ShrubSucculentCalifornia nativeRated for 4 of 6 zones

How often to water Joshua tree, month by month

Your city
Plant width
4 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 Joshua tree 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 the plant covers, 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 plant width

A shrub with its width marked from one side to the other and the circle under it shaded blue

Measure across the plant, from the tips of the leaves on one side to the tips on the other.

Water the whole area the plant covers, shown in blue. The gallons here cover that area.

A wider plant means more gallons each watering, not more waterings. While it is young, measure again each spring.

How to tell it needs water

  • Leaves at the branch tips drooping, yellowing or shriveling in a long drought can indicate severe water stress
  • Yellowing, softening leaves at the crown in soil that stays damp signal too much water or poor drainage
  • A trunk base that turns soft or dark after summer irrigation warns of rot and calls for drier soil
  • Soil that stays wet for days after a soak means the site drains too slowly for this desert plant
  • No flowers on a young tree, or after a mild winter, is normal and not a watering problem

How to water it

  • Plant in full sun in sandy or gravelly soil with perfect drainage, never in a lawn or a low spot
  • Water a new planting deeply but only occasionally in its first warm season, letting the soil dry completely between soaks
  • Apply water in a ring a foot or two out from the trunk rather than against it
  • Keep the ground around it bare or graveled instead of covered with moisture-holding mulch
  • Taper irrigation away once the tree is established, adding a deep soak only in an extreme drought

Through the seasons

A newly planted Joshua tree needs only occasional deep soakings in its first warm season, with the soil drying fully between them. Established trees need little or no summer water. It stays evergreen and keeps its slow pace for life. Flowers come in spring only after good rain and a winter freeze, and young trees may not bloom for decades. Desert winters can be dry, so judge by the soil, not the season. WUCOLS rates Joshua tree very low water on the north-central coast, in South Inland, in the high desert and in the low desert. WUCOLS marks it as not suited to the Central Valley or the south coast.

In pots

A young Joshua tree grows slowly enough to live for some years in a large, deep pot of very gritty, fast-draining mix. Water only when the mix is dry several inches down, which can take a long while in mild weather. Soak it until water runs out, let it drain completely, and leave no water in the saucer. Keep the pot in full sun. In winter, water only rarely and let rain do the rest.

1 Your climate zone six WUCOLS zones, each from its own reference city
Not ratedWUCOLS does not rate Joshua Tree for the Central Valley zone
A year
no figure
Reference
Sacramento climate table
Counts
Plant need, before sprinkler losses

WUCOLS lists Joshua Tree as not suited to this region for the Central Valley zone, so no monthly figure is computed here.

Monthly water need by climate zone

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

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.04––0.080.070.08
Feb0.05––0.090.090.09
Mar0.09––0.130.150.15
Apr0.12––0.160.190.2
May0.15––0.20.240.24
Jun0.16––0.230.290.28
Jul0.16––0.250.30.29
Aug0.15––0.230.280.26
Sep0.12––0.190.210.21
Oct0.09––0.130.150.15
Nov0.05––0.090.090.1
Dec0.03––0.070.070.07
Year1.2––1.842.132.11

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 not suited to this region in the Central Valley, like Joshua tree. Plants that drink alike can share one valve and one schedule.

Chenille PlantAcalypha hispidanot rated, Central Valleyno Central Valley ratingCopperleafAcalypha wilkesiananot rated, Central Valleyno Central Valley ratingYellow Bell BauhiniaBauhinia tomentosanot rated, Central Valleyno Central Valley ratingMagic FlowerCantua buxifolianot rated, Central Valleyno Central Valley ratingClustered Fishtail PalmCaryota mitisnot rated, Central Valleyno Central Valley ratingHawaiian TiCordyline fruticosa (Cordyline terminalis)not rated, Central Valleyno Central Valley ratingFilbertCorylus maximanot rated, Central Valleyno Central Valley ratingPoinsettiaEuphorbia pulcherrimanot rated, Central Valleyno Central Valley ratingWeeping Chinese BanyanFicus benjaminanot rated, Central Valleyno Central Valley ratingRubber PlantFicus elasticanot rated, Central Valleyno Central Valley ratingFranklin TreeFranklinia alatamaha (Gordonia alatamaha)not rated, Central Valleyno Central Valley ratingJungle GeraniumIxora coccineanot rated, Central Valleyno Central Valley ratingOrange JessamineMurraya paniculatanot rated, Central Valleyno Central Valley ratingCommon GuavaPsidium guajavanot rated, Central Valleyno Central Valley ratingOrgan Pipe CactusStenocereus thurberi (Lemaireocereus thurberi)not rated, Central Valleyno Central Valley ratingGiant Bird of ParadiseStrelitzia nicolai (shade in desert)not rated, Central Valleyno Central Valley rating
Minutes for your sprinklers

Turn this into minutes on your water days

Every city page has a calculator that takes Joshua tree, 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 Joshua tree need per day?

In July on the north-central coast, established Joshua tree needs about 0.1 gallons a day for a plant 4 feet across and about 0.3 gallons a day for a plant 8 feet across. Give it in deep waterings spread days apart rather than a little every day, so the whole root zone gets wet.

Does watering for Joshua tree change across California?

Yes. WUCOLS rates Joshua tree separately for each of the six California climate zones: very low water in the North-Central Coastal zone, not suited to this region in the Central Valley zone, not suited to this region in the South Coastal zone, very low water in the South Inland zone, very low water in the High and Intermediate Desert zone, very 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 won't my Joshua tree bloom?

Joshua trees usually flower for the first time at 50 to 70 years old, or about 8 feet tall. Bloom also depends on well-timed rain and a crisp winter freeze, so mild-winter gardens may see few flowers. Extra water will not bring blooms.

How fast does a Joshua tree grow?

Slowly. After a brief early spurt, it adds about half an inch to 3 inches a year. Plan on a small plant for many years rather than pushing it with extra water.

Who pollinates Joshua tree flowers?

A small yucca moth. It gathers pollen and lays eggs in the flower, and its larvae eat some of the developing seeds. The tree depends on this one partner to set seed.

Do birds use Joshua trees?

Yes. Many desert birds nest among the spiky leaves, including Scott's oriole, and woodrats shelter beneath fallen leaves. A garden tree can draw the same wildlife over time.

Can a Joshua tree regrow after damage?

It can resprout from roots and branches, which helps it recover after floods or fire. Give a damaged tree time before removing it.

More plant watering guides

Indian Laurel FigBo-TreeRusty Leaf FigFranklin TreeGolden Trumpet TreeKahili GingerKentia PalmWax Plant

Sources