WateringTimesWatering plan, $19
Vitex agnus-castus, WUCOLS IV

How often to water chaste tree in California

In July in the Central Valley, established chaste tree 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. Chaste tree is a fast-growing, deciduous large shrub or small tree in the mint family. Its aromatic gray-green leaves frame long spikes of lavender, pink or white flowers all summer. Once established it handles heat and drought well, and too much water is the bigger risk, since roots can rot in soil that stays moist.

TreeRated for 6 of 6 zones

How often to water chaste tree, 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 chaste 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 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 4 inches down near the outer stems of an established chaste tree means it is time for a deep soak
  • Leaves still drooping in the evening after a hot day, with dry soil below, point to a thirsty plant
  • Yellowing leaves and dieback over soil that stays moist point to root rot, the main watering risk for this plant
  • Scarred, distorted young leaves and flower buds can point to thrips rather than a water problem
  • Bare branch tips in spring after a hard winter usually mean cold dieback, with new shoots coming from lower wood

How to water it

  • Water around the base and out to the edge of the branches with drip emitters or a slow hose
  • Give each soaking enough time to wet the soil 18 inches down, then wait until it has dried well below the surface
  • Plant in full sun in soil that drains, whether clay, loam or sand, and avoid low wet spots
  • Keep it off frequent lawn-style watering, which holds the root zone too moist for this shrub
  • Mulch lightly with wood chips and move emitters outward as the plant spreads

Through the seasons

Give a new chaste tree regular deep soakings through its first summer, then move to fewer, deeper waterings. It flowers from early summer on new wood, often into fall if you deadhead, and small purple fruits form before the leaves drop. In winter the bare plant needs little water, and rain on the coast and in the valley covers that season. A hard freeze can kill stems back, but the roots usually resprout. Its WUCOLS rating is low water on the north-central coast, in the Central Valley, on the south coast and in South Inland. The high desert and the low desert carry the same low water rating.

In pots

Compact cultivars such as 'Blue Puffball' and 'Blue Diddley' can live in large pots on a sunny patio. Wait until the top 2 inches of mix are dry before watering, and look in on it every couple of days during summer heat. Water slowly until it flows out the bottom, and never leave the pot in a full saucer, since constantly moist mix invites root rot. Cut back watering sharply after the leaves drop, and prune the plant in early spring before new growth starts.

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
0.300.610.921.20.16JAN0.26FEB0.43MAR0.61APR0.83MAY0.99JUN1.07JUL0.95AUG0.72SEP0.47OCT0.22NOV0.14DEC0.300.610.921.20.16JFM0.61AMJ1.07JAS0.47OND
Gallons per square foot per month, Central Valley. Peak 1.07 in Jul, 6.84 a year.

Monthly water need by climate zone

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

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.150.160.310.310.30.31
Feb0.210.260.320.350.370.37
Mar0.350.430.460.520.580.61
Apr0.470.610.560.640.760.78
May0.580.830.640.780.950.98
Jun0.640.990.690.921.141.12
Jul0.641.070.7911.221.14
Aug0.60.950.740.931.121.04
Sep0.50.720.60.740.860.83
Oct0.350.470.460.530.580.6
Nov0.190.220.330.360.370.38
Dec0.120.140.260.270.260.27
Year4.86.846.27.378.518.43

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 low water in the Central Valley, like chaste tree. 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 JulyGreen WattleAcacia decurrenslow water, Central Valley1.07 gal/sq ft in JulySydney Golden WattleAcacia longifolialow 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 chaste 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 often should I water chaste tree in summer?

In July, established chaste tree 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 chaste tree need per day?

In July in the Central Valley, established chaste tree 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 chaste tree change across California?

Yes. WUCOLS rates chaste tree separately for each of the six California climate zones: 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, 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.

When should I prune a chaste tree?

Prune in early spring, since it flowers on new wood. Cutting off faded spikes keeps more blooms coming. A hard cut after bloom gives a showier display the next year.

Is chaste tree invasive?

It reseeds freely and can turn weedy. Deadhead before fruit forms to cut down on seedlings, and pull volunteers while they are small.

Can chaste tree be grown as a tree?

Yes. In warm climates it can be trained to a single trunk and reach about 20 feet. Water a tree-form plant across the whole area under its crown, not just at the trunk.

Does chaste tree attract bees?

Yes. Bees and many other pollinators visit the flowers all summer. Site it a few steps away from doors and busy paths if that matters to you.

Why did my chaste tree die back in winter?

A hard freeze can kill the stems back, most often in the high desert. The roots usually survive and send up new growth that still flowers that summer. Cut out dead wood in early spring and resume watering once growth starts.

More plant watering guides

Purple MulleinBailey AcaciaSilver WattleGreen WattleSydney Golden WattleBlackwood AcaciaBlue Leaf WattleSilvery Yarrow

Sources