WateringTimesWatering plan, $19
Ficus elastica, WUCOLS IV

How often to water rubber plant in California

In July on the south coast, established rubber plant in loam needs a deep watering about every 11 days: about 55 gallons each time under a 10 foot canopy, about 35 gallons a week. Rubber plant is a broadleaf evergreen fig with stiff, glossy leaves about a foot long and a milky sap. It is widely grown in containers, and in mild, nearly frost-free gardens it can become a large tree. It wants regular water with good drainage, and it sheds leaves when overwatered or chilled.

ShrubTreeRated for 2 of 6 zones

How often to water rubber plant, 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 rubber plant 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 2 to 3 inches down beneath an in-ground rubber plant signals that it needs a deep soak
  • Large leaves hanging limp and losing their gloss over dry soil can indicate thirst in summer heat
  • Leaves falling while the soil stays wet can indicate overwatering, though a cold snap causes the same loss
  • A few lower leaves turning yellow and dropping over time is normal turnover on a healthy plant
  • Sticky leaves, cottony clusters or fine webbing point to scale, mealybugs or spider mites rather than thirst

How to water it

  • Water an in-ground rubber plant across the root area beneath its canopy rather than at the trunk
  • Soak the soil about a foot deep, then let the top couple of inches dry before the next soak
  • Plant in well-drained ground, since an overwatered rubber plant sheds its leaves
  • Mulch the root area with wood chips, keeping them a few inches back from the trunk
  • Extend drip lines outward as the canopy spreads

Through the seasons

Keep a new in-ground rubber plant from drying out through its first summer while roots grow into the surrounding soil. Established trees still need deep soakings in the dry months, with the surface allowed to dry between them. Growth slows from fall to late winter, so cut back watering then. This evergreen is intolerant of cold, and a sharp temperature drop causes leaf loss. Winter rain on the south coast often covers the cool months, but check South Inland soil during dry spells. WUCOLS rates rubber plant moderate water on the south coast and in South Inland. WUCOLS marks it as not suited to the north-central coast, the Central Valley, the high desert and the low desert.

In pots

Rubber plant is widely grown in containers, indoors or on a shaded patio. Use a soil-based potting mix and a pot with open drainage holes. Feel the mix 2 inches down every few days in summer, and water once it is dry at that depth. Soak until water runs from the holes, then empty the saucer. Give it bright, indirect light with protection from afternoon sun. From fall to late winter growth slows, so water much less. Keep the pot away from cold drafts, which cause leaf drop.

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

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

Monthly water need by climate zone

Rubber Plant: gallons per square foot per month, by WUCOLS climate zone

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan––0.780.78––
Feb––0.810.87––
Mar––1.151.3––
Apr––1.41.61––
May––1.611.95––
Jun––1.742.29––
Jul––1.982.51––
Aug––1.862.33––
Sep––1.491.86––
Oct––1.151.33––
Nov––0.840.9––
Dec––0.650.68––
Year––15.518.41––

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 not suited to this region in the Central Valley, like rubber plant. Plants that drink alike can share one valve and one schedule.

Chenille PlantAcalypha hispidanot rated, Central Valleyno Central Valley ratingCopperleafAcalypha wilkesiananot rated, Central Valleyno Central Valley ratingSugar MapleAcer saccharumnot rated, Central Valleyno Central Valley ratingQueensland KauriAgathis robustanot rated, Central Valleyno Central Valley ratingCherimoyaAnnona cherimolanot rated, Central Valleyno Central Valley ratingYellow Bell BauhiniaBauhinia tomentosanot rated, Central Valleyno Central Valley ratingPurple Orchid TreeBauhinia variegata (purpurea)not rated, Central Valleyno Central Valley ratingToogBischofia javanicanot rated, Central Valleyno Central Valley ratingMagic FlowerCantua buxifolianot rated, Central Valleyno Central Valley ratingClustered Fishtail PalmCaryota mitisnot rated, Central Valleyno Central Valley ratingWhite SapoteCasimiroa edulisnot rated, Central Valleyno Central Valley ratingHawaiian TiCordyline fruticosa (Cordyline terminalis)not 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 rating
Minutes for your sprinklers

Turn this into minutes on your water days

Every city page has a calculator that takes rubber plant, 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 rubber plant in summer?

In July, established rubber plant in loam needs a deep watering about every 11 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 rubber plant need per day?

In July on the south coast, established rubber plant needs about 5.0 gallons a day under a 10 foot canopy and about 20 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 rubber plant change across California?

Yes. WUCOLS rates rubber plant 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, moderate 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.

Why is my rubber plant dropping leaves?

Overwatering, a sudden temperature drop and cold drafts can each cause leaf loss. Check whether the soil is staying wet before you add water. An occasional yellow leaf at the bottom of the plant is normal.

Is rubber plant sap harmful?

The milky sap drips from any cut leaf or stem. The plant is listed as a problem for cats, dogs and horses, so keep prunings away from animals. Wear gloves when pruning to keep sap off your hands.

Can I keep my rubber plant smaller?

Yes. Pruning the main stems encourages a bushier plant, while leaving them unpruned gives a tall, narrow form. Expect sap to drip from fresh cuts for a while.

Can rubber plant grow outdoors in California?

In the ground it suits mild, nearly frost-free gardens, where it can grow into a large tree. It does poorly with cold, so in colder areas keep it in a pot you can move indoors. Bring it in before the first chilly nights.

How do I clean rubber plant leaves?

Wipe dust off the large leaves with a damp, soft cloth or sponge. Clean leaves look better and take in light more easily. Check the undersides for scale or mealybugs while you work.

How much light does a rubber plant need?

Bright, indirect light or partial shade suits it, with protection from hot afternoon sun. Low light slows growth, so a plant in a dim room dries more slowly and needs less water.

More plant watering guides

PoinsettiaRoxburgh FigIndian BanyanWeeping Chinese BanyanFiddleleaf FigMoreton Bay FigIndian Laurel FigBo-Tree

Sources