WateringTimesWatering plan, $19
Acacia decurrens, WUCOLS IV

How often to water green wattle in California

In July in the Central Valley, established green wattle in loam needs a deep watering about every 20 days: about 55 gallons each time under a 10 foot canopy, about 19 gallons a week. Green wattle is a fast-growing evergreen tree or large shrub from rocky foothills and valleys of southeastern Australia, reaching 15 to 50 feet. Its dark gray-green leaves are divided into many feathery leaflets, and bright yellow ball-shaped flower clusters are followed by brown seedpods. It suckers into thickets and self-sows, so it can turn weedy.

TreeRated for 4 of 6 zones

How often to water green wattle, 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 green wattle 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 newly planted wattle with soil dry well below the surface in its first summer is ready for a slow soak
  • Feathery leaves dropping heavily in a long drought on an unestablished tree can signal thirst
  • Yellowing leaves and dieback over wet, poorly drained soil point to root rot
  • Many new shoots coming up around the trunk are suckers, not a sign of water need

How to water it

  • Water a young tree deeply and let the soil dry well between soakings
  • Once established, water rarely or not at all on the coast
  • Plant in full sun in well-drained soil
  • Pull suckers and seedlings while they are small
  • Keep it away from wildlands, where seed can escape

Through the seasons

Water a new tree through its first summer or two until roots spread. After that, it needs little to no summer water near the coast, and only occasional deep soaks inland. Bright yellow flower clusters form at the branch ends, then brown pods follow. On the north-central coast, WUCOLS rates green wattle very low water. The Central Valley, the south coast and South Inland give it a low water rating. WUCOLS marks it as not suited to the high desert or the low desert.

In pots

Green wattle grows too fast and large for a pot to hold it for long. A young plant can stay a season or two in a big container of fast-draining mix. Pour water in once the upper few inches have dried, then let it drain. In summer heat, check the pot every few days. Never let it sit in a saucer of water. In winter, rain is usually enough, so water only if the mix dries out.

1 Your climate zone six WUCOLS zones, each from its own reference city
1.07gal per sq ft in JulyLow water use in the Central Valley zone
A year
6.84 gal per sq ft
Reference
Sacramento climate table
Counts
Plant need, before sprinkler losses
0.270.540.801.10.16JAN0.26FEB0.43MAR0.61APR0.83MAY0.99JUN1.07JUL0.95AUG0.72SEP0.47OCT0.22NOV0.14DEC0.270.540.801.10.16JFM0.61AMJ1.07JAS0.47OND
Gallons per square foot per month, Central Valley. Peak 1.07 in Jul, 6.84 a year.

Monthly water need by climate zone

Green Wattle: gallons per square foot per month, by WUCOLS climate zone

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.040.160.310.31––
Feb0.050.260.320.35––
Mar0.090.430.460.52––
Apr0.120.610.560.64––
May0.150.830.640.78––
Jun0.160.990.690.92––
Jul0.161.070.791––
Aug0.150.950.740.93––
Sep0.120.720.60.74––
Oct0.090.470.460.53––
Nov0.050.220.330.36––
Dec0.030.140.260.27––
Year1.26.846.27.37––

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 low water in the Central Valley, like green wattle. Plants that drink alike can share one valve and one schedule.

Olive TreesOlea europaea ssp. & cvs.low water, Central Valley1.07 gal/sq ft in JulyFig TreesFicus carica ssp. & cvs.low water, Central Valley1.07 gal/sq ft in JulyCrape MyrtleLagerstroemia spp., hybrids & cvs.low water, Central Valley1.07 gal/sq ft in JulyAloeAloe spp. & cvs.low water, Central Valley1.07 gal/sq ft in JulyPomegranate TreesPunica granatumlow water, Central Valley1.07 gal/sq ft in JulyEucalyptusEucalyptus polyanthemoslow water, Central Valley1.07 gal/sq ft in JulyPine TreesPinus canariensislow water, Central Valley1.07 gal/sq ft in JulyJunipersJuniperus spp. & cvs.low water, Central Valley1.07 gal/sq ft in JulyTexas Red OakQuercus buckleyilow water, Central Valley1.07 gal/sq ft in JulyPortuguese OakQuercus faginealow water, Central Valley1.07 gal/sq ft in JulySoapbark TreeQuillaja saponarialow water, Central Valley1.07 gal/sq ft in JulyNecklace TreeSophora affinislow water, Central Valley1.07 gal/sq ft in JulyBailey AcaciaAcacia baileyanalow water, Central Valley1.07 gal/sq ft in JulySilver WattleAcacia dealbatalow water, Central Valley1.07 gal/sq ft in JulySydney Golden WattleAcacia longifolialow water, Central Valley1.07 gal/sq ft in JulyBlackwood AcaciaAcacia melanoxylonlow water, Central Valley1.07 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 green wattle, 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 green wattle in summer?

In July, established green wattle in loam needs a deep watering about every 20 days in the Central Valley, about every 27 days on the south coast 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 green wattle need per day?

In July in the Central Valley, established green wattle needs about 2.7 gallons a day under a 10 foot canopy and about 11 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 green wattle change across California?

Yes. WUCOLS rates green wattle separately for each of the six California climate zones: very low water in the North-Central Coastal zone, low water in the Central Valley zone, low water in the South Coastal zone, low 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 green wattle invasive?

It self-sows and can be weedy or invasive. It also spreads by suckers into thickets. Keep it away from wildlands.

How fast does green wattle grow?

It grows fast, to 15 to 50 feet tall and 10 to 25 feet wide. Give it plenty of room. It is not a tree for a small yard.

What does green wattle need to grow well?

It needs full sun and well-drained soil. It grows wild in rocky soil. Heavy, wet soil is a risk.

Why are there shoots around my wattle?

Green wattle spreads by suckers from its roots. Pull or cut them while small. Check the area each season.

Does green wattle need summer water?

Near the coast, an established tree needs very little. Inland, give occasional deep soaks in long dry spells. Young trees need regular water at first.

More plant watering guides

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Sources