WateringTimesWatering plan, $19
Acacia podalyriifolia, WUCOLS IV

How often to water pearl acacia in California

In July in the Central Valley, established pearl acacia in loam needs a deep soak only about once a month or less: about 55 gallons each time under a 10 foot canopy. Pearl acacia is a fast-growing evergreen from eastern Australia, grown as a small tree or a large shrub. Its rounded, silvery leaves are really flattened leaf stalks, and fluffy golden flower balls cover it in late winter or early spring. It wants full sun, sharp drainage and a dry summer, and it lives longer when it is not overwatered.

ShrubTreeRated for 4 of 6 zones

How often to water pearl acacia, 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 pearl acacia 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 3 to 4 inches down at the edge of a young pearl acacia's root ball means it is ready for a deep soak
  • New shoots that droop on a young plant during a heat wave, with dry soil below, point to a thirsty root zone
  • Yellowing, dropping leaves while the soil stays damp through summer point to overwatering, which shortens this acacia's life
  • Water still standing in the planting basin hours after a soak means the soil drains too slowly for this tree

How to water it

  • Water a young pearl acacia over its root ball and a little beyond, then widen the wet area as the canopy spreads
  • Soak slowly until water reaches 12 to 18 inches down, then let the soil dry well before the next soak
  • Use drip emitters or a slow hose under the outer canopy, not lawn sprinklers that keep the soil wet in summer
  • Plant on a slope, a low mound or in gravelly soil that drains fast, and avoid spots where winter water pools
  • Spread coarse mulch over the root zone and keep it a few inches back from the trunk

Through the seasons

Give a new pearl acacia regular deep soakings through its first summer, while its roots grow out into the native soil. After that, water it sparingly in summer unless the soil drains very well. This evergreen keeps its silvery leaves all year and blooms in late winter or early spring, followed by large brown pods. Pruning, when needed, follows the bloom. WUCOLS rates it very low water on the north-central coast and in the Central Valley, where winter rain covers the cool months. It rates low water on the south coast and moderate water in South Inland. WUCOLS marks it as not suited to the high desert or the low desert.

In pots

A young pearl acacia can live in a large pot for a season or two before it goes in the ground. It grows fast, so expect it to outgrow the pot quickly. Use a gritty, fast-draining mix and a pot with open drainage holes. Check the mix 2 to 3 inches down every few days in summer heat. Water until it runs from the holes, then empty the saucer at once, since roots that sit wet shorten its life. In winter, water only when the mix has dried well below the surface.

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
0.631.31.92.50.04JAN0.07FEB0.11MAR0.15APR0.21MAY0.25JUN0.27JUL0.24AUG0.18SEP0.12OCT0.06NOV0.03DEC0.631.31.92.50.04JFM0.15AMJ0.27JAS0.12OND
Gallons per square foot per month, Central Valley. Peak 0.27 in Jul, 1.71 a year.

Monthly water need by climate zone

Pearl Acacia: gallons per square foot per month, by WUCOLS climate zone

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.040.040.310.78––
Feb0.050.070.320.87––
Mar0.090.110.461.3––
Apr0.120.150.561.61––
May0.150.210.641.95––
Jun0.160.250.692.29––
Jul0.160.270.792.51––
Aug0.150.240.742.33––
Sep0.120.180.61.86––
Oct0.090.120.461.33––
Nov0.050.060.330.9––
Dec0.030.030.260.68––
Year1.21.716.218.41––

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 pearl acacia. Plants that drink alike can share one valve and one schedule.

OleanderNerium 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 JulyOak TreesQuercus agrifoliavery low water, Central Valley0.27 gal/sq ft in JulySpanish BroomSpartium junceumvery low water, Central Valley0.27 gal/sq ft in JulySalt CedarTamarix aphyllavery low water, Central Valley0.27 gal/sq ft in JulyBig SagebrushArtemisia tridentatavery 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 JulyCalifornia Scrub OakQuercus berberidifoliavery 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 JulyCreosote BushLarrea tridentata ssp. & cvs.very low water, Central Valley0.27 gal/sq ft in JulyPurple SageSalvia leucophylla ssp. & cvs.very low water, Central Valley0.27 gal/sq ft in JulyBlack SageSalvia mellifera 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 pearl acacia, 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 pearl acacia in summer?

In July, established pearl acacia in loam needs a deep watering about once a month or less 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 pearl acacia need per day?

In July in the Central Valley, established pearl acacia 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 pearl acacia change across California?

Yes. WUCOLS rates pearl acacia 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, 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, not suited to this region in the Low Desert zone. The monthly table above shows how the same rating translates into different gallon amounts as reference evapotranspiration changes.

Is pearl acacia invasive?

It can be. University of California notes describe it as potentially weedy or invasive, and it has naturalized outside its home range in Australia. Pull seedlings while they are small, and avoid planting it next to wild land.

Can pearl acacia be kept as a shrub?

Yes. Prune it back hard right after flowering to hold a bushy shape. It can also be trained into a small tree with a rounded, open head for a patio.

How cold can pearl acacia take?

It is hardy to about 25 degrees F, and a few degrees lower for a short time. Longer or harder freezes can damage it, so it suits mild winter gardens best.

Why is my pearl acacia not living long?

Too much summer water is a common reason. This acacia is relatively long lived when it is not overwatered. Keep it out of lawns and beds on frequent sprinklers, and plant it where the soil drains fast.

Does pearl acacia grow near the coast?

Yes. It is listed as a good seaside plant and handles dry summers. On the north-central coast WUCOLS rates it very low water once established.

Is pearl acacia deer resistant?

It is listed as deer tolerant, so it is a reasonable choice where deer visit. Choose its spot for sun and drainage first, since those decide how well it grows.

More plant watering guides

California BuckeyeItalian ArumToyonTree of HeavenFox Tail AgaveSaltbushParry's AgaveOleander

Sources