WateringTimesWatering plan, $19
Olneya tesota, WUCOLS IV

How often to water desert ironwood in California

In July in the South Inland zone, established desert ironwood in loam needs a deep watering about every 22 days: about 55 gallons each time under a 10 foot canopy, about 18 gallons a week. Desert ironwood is a spiny Sonoran Desert tree with gray-green leaflets, smooth gray bark and wood so dense it will not float. It wants full sun, good drainage and only a little water once established. Under drought or cold it sheds its leaves, and it drops them again just before it flowers.

TreeCalifornia nativeRated for 3 of 6 zones

How often to water desert ironwood, 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 desert ironwood 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

  • Soil dry 6 inches down beyond a young ironwood's root ball means it is ready for a slow, deep soak
  • Heavy leaf drop on a young tree in summer heat, with dry soil below, points to drought stress
  • Leaves falling just before the spring bloom are part of the tree's normal cycle, not a call for water
  • Leaf loss after a cold snap is a response to cold, so check the soil before adding water
  • Yellowing leaves over ground that stays wet for days point to poor drainage around this desert tree

How to water it

  • Water a young ironwood slowly over its root ball and a ring of soil just past it, then widen the ring as the canopy spreads
  • Soak until water reaches about 2 feet down, then let the soil dry well before the next soak
  • Set drip emitters under the outer canopy of an older tree rather than against the spiny trunk
  • Plant in sandy or gravelly ground that drains freely, never in a low spot where rain water stands
  • Cover the root zone with gravel or coarse mulch, kept a few inches back from the trunk

Through the seasons

Give a young ironwood deep, spaced soakings through its first few summers while its roots spread. Once established it survives on desert rainfall, though growth slows a great deal without some summer water. Leaves fall before the late April and May bloom, which does not come every year. Summer heat is when soil checks matter most. Desert winters bring little rain, so check the soil during long dry spells. WUCOLS rates it low water in South Inland, the high desert and the low desert. WUCOLS marks it as not suited to the north-central coast, the Central Valley or the south coast.

In pots

Desert ironwood grows into a sizable tree, so a container suits it only while it waits for a place in the ground. Use a deep pot and a gritty mix that drains fast. Check the mix 2 inches down every few days in summer, and daily during a desert heat wave. Water until it runs from the drainage holes, then empty the saucer. Keep the spiny young tree away from doorways and paths. Cold nights can make it drop leaves, so let the mix dry further between winter soakings.

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

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

Monthly water need by climate zone

Desert Ironwood: gallons per square foot per month, by WUCOLS climate zone

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan–––0.310.30.31
Feb–––0.350.370.37
Mar–––0.520.580.61
Apr–––0.640.760.78
May–––0.780.950.98
Jun–––0.921.141.12
Jul–––11.221.14
Aug–––0.931.121.04
Sep–––0.740.860.83
Oct–––0.530.580.6
Nov–––0.360.370.38
Dec–––0.270.260.27
Year–––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 not suited to this region in the Central Valley, like desert ironwood. Plants that drink alike can share one valve and one schedule.

Sugar MapleAcer saccharumnot rated, Central Valleyno Central Valley ratingQueensland KauriAgathis robustanot rated, Central Valleyno Central Valley ratingCherimoyaAnnona cherimolanot rated, Central Valleyno Central Valley ratingPurple Orchid TreeBauhinia variegata (purpurea)not rated, Central Valleyno Central Valley ratingToogBischofia javanicanot rated, Central Valleyno Central Valley ratingClustered Fishtail PalmCaryota mitisnot rated, Central Valleyno Central Valley ratingWhite SapoteCasimiroa edulisnot rated, Central Valleyno Central Valley ratingFilbertCorylus maximanot rated, Central Valleyno Central Valley ratingSpotted GumCorymbia maculata (Eucalyptus maculata)not rated, Central Valleyno Central Valley ratingDove TreeDavidia involucratanot rated, Central Valleyno Central Valley ratingRoyal PoincianaDelonix regianot rated, Central Valleyno Central Valley ratingTriangle PalmDypsis decaryinot rated, Central Valleyno Central Valley ratingMountain White GumEucalyptus dalrympleananot rated, Central Valleyno Central Valley ratingRainbow EucalyptusEucalyptus degluptanot rated, Central Valleyno Central Valley ratingRoxburgh FigFicus auriculatanot rated, Central Valleyno Central Valley ratingIndian BanyanFicus benghalensisnot 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 desert ironwood, 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 desert ironwood need per day?

In July in the South Inland zone, established desert ironwood needs about 2.5 gallons a day under a 10 foot canopy and about 10 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 desert ironwood change across California?

Yes. WUCOLS rates desert ironwood separately for each of the six California climate zones: not suited to this region 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, 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.

Is desert ironwood messy?

No. Its leaves, flowers and pods are small, so litter is light. The paired spines on its twigs are the bigger concern. Plant it away from paths, pools and play areas.

Why did my desert ironwood drop its leaves?

Desert ironwood sheds leaves late in a drought, after cold weather and just before it blooms. Dig down a few inches to tell which. Dry soil in summer heat calls for a deep soak, while moist soil means water is not the cause.

Why is my desert ironwood not blooming?

The tree does not flower every year, even in the wild. When it does, small pea-like flowers come in late April and May. Steady deep soakings in a dry spring will not force a bloom, so wait for the next season.

Can desert ironwood grow near the coast?

No, WUCOLS rates it only for the inland and desert zones and marks both coastal zones as not suited. It is a Sonoran Desert tree that tolerates extreme heat. If citrus grows well in your garden, ironwood may grow there too.

Should I prune a young desert ironwood?

Yes, pruning helps a young tree develop a more upright habit. Mature trees keep an irregular canopy. Wear thick gloves, since the paired spines are sharp.

How long does desert ironwood live?

It can live for centuries. In the wild it shelters young plants of other species and gives food and cover to wildlife. Once established, it needs only an occasional deep soak in a long dry spell.

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Sources