WateringTimesWatering plan, $19
Myoporum laetum ssp. & cvs., WUCOLS IV

How often to water coast myoporum in California

In July in the Central Valley, established coast myoporum 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. Coast myoporum is a fast growing evergreen shrub or small tree from New Zealand, long planted as a dense screen near the beach. Small white flowers with purple spots open in summer, followed by reddish purple fruit. It needs little water once established, but it is invasive in California and prone to a leaf-galling thrips.

ShrubTreeRated for 4 of 6 zones

How often to water coast myoporum, 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 coast myoporum 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 to 6 inches down at the edge of a young myoporum's root ball means it is time for a deep soak
  • Leaves hanging limp on a young plant in afternoon heat, with dry soil below, point to a dry root zone
  • Twisted, folded, gall-like new leaves and stunted shoot tips are myoporum thrips damage, which watering will not fix
  • Soil still soggy a few days after a soak means the spot drains poorly, so wait longer before the next one

How to water it

  • Water a young coast myoporum over its root ball and a ring of soil beyond it, then widen the ring as the canopy grows
  • Soak slowly until water reaches about 18 inches down, then let the top several inches dry before the next soak
  • Run drip line along both sides of a myoporum hedge, with emitters set a few inches out from the trunks
  • Plant in full sun for the densest screen, since light shade gives thinner growth
  • Spread wood chip mulch under the hedge to slow drying, keeping it pulled back from the trunks

Through the seasons

Water a new coast myoporum deeply through its first summer, until its roots spread well past the planting hole. After that it grows fast on little extra water. It keeps its leaves all year and flowers in summer. WUCOLS rates it low water on the north-central coast, in the Central Valley and on the south coast. Winter rain covers the cool months in those three zones. It rates moderate water in South Inland, where summer soil checks matter more. WUCOLS has not evaluated it for the high desert or the low desert. Nights colder than about 25 degrees F can damage it.

In pots

Coast myoporum can reach 30 feet, so a container is only a short stop before it goes in the ground. Check a nursery can 2 inches down every few days in summer, and daily during South Inland heat waves. Water until it drains from the holes, then empty the saucer so the roots are not left in standing water. This fast grower fills a can with roots quickly. A plant that dries out within a day has outgrown its pot. In winter, check the mix after rain before adding more water.

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
0.631.31.92.50.16JAN0.26FEB0.43MAR0.61APR0.83MAY0.99JUN1.07JUL0.95AUG0.72SEP0.47OCT0.22NOV0.14DEC0.631.31.92.50.16JFM0.61AMJ1.07JAS0.47OND
Gallons per square foot per month, Central Valley. Peak 1.07 in Jul, 6.84 a year.

Monthly water need by climate zone

Coast Myoporum: gallons per square foot per month, by WUCOLS climate zone

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.150.160.310.78––
Feb0.210.260.320.87––
Mar0.350.430.461.3––
Apr0.470.610.561.61––
May0.580.830.641.95––
Jun0.640.990.692.29––
Jul0.641.070.792.51––
Aug0.60.950.742.33––
Sep0.50.720.61.86––
Oct0.350.470.461.33––
Nov0.190.220.330.9––
Dec0.120.140.260.68––
Year4.86.846.218.41––

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

LavenderLavandula spp. & cvs.low water, Central Valley1.07 gal/sq ft in JulyRosemaryRosmarinus officinalislow water, Central Valley1.07 gal/sq ft in JulyBougainvilleaBougainvillea & spp. & cvs.low water, Central Valley1.07 gal/sq ft in JulyOlive 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 JulyLantanaLantana camara ssp. & cvs.low water, Central Valley1.07 gal/sq ft in JulySalviaSalvia greggii ssp., cvs. & hybridslow water, Central Valley1.07 gal/sq ft in JulyAloeAloe spp. & cvs.low water, Central Valley1.07 gal/sq ft in JulySucculentsEcheveria 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 JulyRussian SagePerovskia spp. & cvs.low water, Central Valley1.07 gal/sq ft in JulySagebrushArtemisia spp. (shrubby)low 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 coast myoporum, 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 coast myoporum in summer?

In July, established coast myoporum 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 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 coast myoporum need per day?

In July in the Central Valley, established coast myoporum 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 coast myoporum change across California?

Yes. WUCOLS rates coast myoporum 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, moderate water in the South Inland zone, not evaluated in the High and Intermediate Desert zone, not evaluated in the Low Desert zone. The monthly table above shows how the same rating translates into different gallon amounts as reference evapotranspiration changes.

Is coast myoporum invasive?

Yes. The California Invasive Plant Council lists it as invasive, and it has escaped gardens along the coast and around San Francisco Bay. It can form dense stands that crowd out native plants. WUCOLS strongly discourages using it in south coast landscapes.

What is damaging my myoporum's new leaves?

Twisted, galled and folded new leaves are the work of myoporum thrips, an invasive pest on the California coast. Lasting damage to the shoot tips can kill well established plants. Extra water will not help. Prune off and bag infested tips, but avoid heavy pruning, which stresses the plant.

Is coast myoporum poisonous?

Yes. Its leaves contain compounds that can cause fatal liver damage in livestock. Keep grazing animals away from it, and do not leave clippings where they can eat them.

Can coast myoporum grow by the beach?

Yes. It has long been planted as a beachside screen. Give it full sun for the densest growth.

How tall does a myoporum hedge get?

The common form can reach 30 feet tall and 20 feet wide, with leaves all the way to its base. A compact form makes a dense hedge to about 15 feet. It takes shaping well, but heavy cuts stress it.

How cold can coast myoporum take?

It is hardy to about 25 degrees F, and colder nights can damage it. A frost damaged plant needs water only when the soil below is dry.

More plant watering guides

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Sources