WateringTimesWatering plan, $19
Euphorbia tirucalli, WUCOLS IV

How often to water milk bush in California

In July on the south coast, established milk bush in loam needs a deep soak only about once a month or less: about 8.8 gallons each time for a plant 4 feet across. Milk bush, also called pencil tree or pencil cactus, is a spineless African succulent with clusters of smooth, pencil-thin green branches that store water. The cultivar 'Sticks on Fire' turns red and gold in cool weather. It needs very little water and sharp drainage, and its milky sap is caustic.

ShrubSucculentRated for 2 of 6 zones

How often to water milk bush, month by month

Your city
Plant width
4 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 milk bush 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 the plant covers, 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 plant width

A shrub with its width marked from one side to the other and the circle under it shaded blue

Measure across the plant, from the tips of the leaves on one side to the tips on the other.

Water the whole area the plant covers, shown in blue. The gallons here cover that area.

A wider plant means more gallons each watering, not more waterings. While it is young, measure again each spring.

How to tell it needs water

  • Soil dry 3 to 4 inches down around the trunk means an established milk bush can take a deep soak
  • Pencil branches that shrivel or wrinkle during a long hot, dry spell show the plant is drawing on stored water
  • Soft, dark, mushy stems at the base over damp soil signal root rot from overwatering
  • Bare green branches with few leaves are normal, since its tiny leaves fall off early
  • Red and gold stems on 'Sticks on Fire' fading to yellow in summer is a seasonal change, not stress

How to water it

  • Water deeply but rarely, and only after the soil has dried well below the surface
  • Plant in fast-draining sandy, gravelly or rocky soil without rich organic amendments
  • Give it afternoon shade in the low desert, where summers run hot
  • Keep lawn sprinklers and other frequent irrigation away from its roots
  • Leave it unwatered through winter on the south coast unless rain fails for weeks

Through the seasons

Water a new milk bush lightly until it roots in, then let it get by on rain and occasional deep soakings. It grows slowly and stays green all year, with tiny leaves on new growth that drop early. Small greenish yellow flowers with yellow glands appear at the branch tips in spring. Rain covers the cool months on the south coast, while low desert plants may need a rare winter soak in a long dry spell. WUCOLS rates milk bush very low water on the south coast and low water in the low desert. The high desert, South Inland, the Central Valley and the north-central coast are all zones WUCOLS marks as not suited.

In pots

Milk bush is often grown in a pot, outdoors or as a bright houseplant. Use a gritty cactus mix in a pot with a large drainage hole. Check the mix every few days in summer, but water only when it is dry most of the way down. Soak until water runs out, then empty the saucer at once, since soggy mix rots the roots. In winter, water rarely, and bring the pot in before frost, since this succulent is tender.

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

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

Monthly water need by climate zone

Milk Bush: gallons per square foot per month, by WUCOLS climate zone

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan––0.08––0.31
Feb––0.08––0.37
Mar––0.11––0.61
Apr––0.14––0.78
May––0.16––0.98
Jun––0.17––1.12
Jul––0.2––1.14
Aug––0.19––1.04
Sep––0.15––0.83
Oct––0.11––0.6
Nov––0.08––0.38
Dec––0.07––0.27
Year––1.55––8.43

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 not suited to this region in the Central Valley, like milk bush. 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 ratingYellow Bell BauhiniaBauhinia tomentosanot rated, Central Valleyno Central Valley ratingMagic FlowerCantua buxifolianot rated, Central Valleyno Central Valley ratingClustered Fishtail PalmCaryota mitisnot rated, Central Valleyno Central Valley ratingHawaiian TiCordyline fruticosa (Cordyline terminalis)not rated, Central Valleyno Central Valley ratingFilbertCorylus maximanot rated, Central Valleyno Central Valley ratingPoinsettiaEuphorbia pulcherrimanot rated, Central Valleyno Central Valley ratingWeeping Chinese BanyanFicus benjaminanot rated, Central Valleyno Central Valley ratingRubber PlantFicus elasticanot rated, Central Valleyno Central Valley ratingFranklin TreeFranklinia alatamaha (Gordonia alatamaha)not rated, Central Valleyno Central Valley ratingJungle GeraniumIxora coccineanot rated, Central Valleyno Central Valley ratingOrange JessamineMurraya paniculatanot rated, Central Valleyno Central Valley ratingCommon GuavaPsidium guajavanot rated, Central Valleyno Central Valley ratingOrgan Pipe CactusStenocereus thurberi (Lemaireocereus thurberi)not rated, Central Valleyno Central Valley ratingGiant Bird of ParadiseStrelitzia nicolai (shade in desert)not 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 milk bush, 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 much water does milk bush need per day?

In July on the south coast, established milk bush needs about 0.1 gallons a day for a plant 4 feet across and about 0.3 gallons a day for a plant 8 feet across. Give it in deep waterings spread days apart rather than a little every day, so the whole root zone gets wet.

Does watering for milk bush change across California?

Yes. WUCOLS rates milk bush 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, very low water in the South Coastal zone, not suited to this region in the South Inland zone, not suited to this region 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.

Is milk bush sap dangerous?

Yes. The milky sap is caustic and can cause severe skin irritation and eye damage, and it blisters the mouth if eaten. Wear gloves and eye protection when you cut it, and get medical help after any eye contact.

Why is my 'Sticks on Fire' losing its red color?

Its stems fade to yellow in summer heat and color up red again in cool weather. The change is seasonal and does not call for more water.

Is milk bush a cactus?

No. Despite the name pencil cactus, it is a spineless succulent in the spurge family. It bleeds milky sap when cut, which a cactus does not.

How big does milk bush get?

In the ground it can reach 15 to 25 feet tall. 'Sticks on Fire' stays smaller at about 4 to 8 feet, and potted plants stay smaller still.

Can milk bush grow as a hedge?

In frost-free gardens it is used as a hedge or barrier. Plant it where people and pets will not brush against broken stems, since the sap is caustic.

More plant watering guides

ToogMagic FlowerClustered Fishtail PalmWhite SapoteHawaiian TiFilbertSpotted GumDove Tree

Sources