WateringTimesWatering plan, $19
Fouquieria columnaris, WUCOLS IV

How often to water boojum in California

In July on the south coast, established boojum 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. The boojum is a strange, slow-growing succulent tree from rocky slopes of Baja California and a small area of mainland Sonora. Its tapering, carrot-like trunk can reach 20 to 50 feet, bristling with short, spiny branches. Small leaves appear after rain and drop as the soil dries, sometimes several times a year. It is related to the ocotillo.

ShrubSucculentRated for 3 of 6 zones

How often to water boojum, 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 boojum 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

  • Leaves appearing on the branches means the boojum has had water, not that it needs more
  • Leaves dropping as the soil dries is normal behavior
  • A soft, bruised or shriveling trunk base in wet soil points to rot
  • A trunk looking shrunken after a very long, hot dry spell can signal thirst

How to water it

  • Water very rarely, and only after the soil has dried completely
  • Water in the cooler months, when it grows
  • Plant in full sun in soil with excellent drainage
  • Keep it far from lawns and sprinklers
  • Handle the soft trunk with care, since it bruises easily

Through the seasons

Water a young plant lightly during its first cool season, when it is growing, then cut back. Established boojums grow in cooler weather and need only rare, deep water. Its small leaves come and go with soil moisture, and creamy flowers appear near the top in late summer and fall. WUCOLS rates boojum very low water on the south coast, in South Inland and in the low desert. WUCOLS marks it as not suited to the north-central coast, the Central Valley or the high desert.

In pots

Boojums are often grown in large, deep pots of fast-draining cactus mix, which keeps their soft trunks safe from soggy ground. Water only after the mix is dry all the way through, then let it drain completely. In summer heat, water sparingly. Never leave water standing in the saucer. A pot also lets you move it out of the rain during cold, wet spells.

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

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

Monthly water need by climate zone

Boojum: gallons per square foot per month, by WUCOLS climate zone

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan––0.080.08–0.08
Feb––0.080.09–0.09
Mar––0.110.13–0.15
Apr––0.140.16–0.2
May––0.160.2–0.24
Jun––0.170.23–0.28
Jul––0.20.25–0.29
Aug––0.190.23–0.26
Sep––0.150.19–0.21
Oct––0.110.13–0.15
Nov––0.080.09–0.1
Dec––0.070.07–0.07
Year––1.551.84–2.11

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 boojum. 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 boojum, 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 boojum in summer?

In July, established boojum in loam needs a deep watering about once a month or less on the south coast and about once a month or less 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 boojum need per day?

In July on the south coast, established boojum 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 boojum change across California?

Yes. WUCOLS rates boojum 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, very low water in the South Inland zone, not suited to this region in the High and Intermediate Desert zone, very 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.

Why does my boojum keep losing its leaves?

Its leaves are short-lived and depend on soil moisture. They can come and go several times a year. That is normal.

When does a boojum grow?

It grows during cooler weather, when winter rain or fog brings moisture. Summer is a slow time. Water little then.

How tall does a boojum get?

It grows very slowly, eventually to 20 to 50 feet. It is a plant for patient gardeners. Its trunk tapers like an upside-down carrot.

Is a boojum related to ocotillo?

Yes, both belong to the same plant family. Both drop leaves when dry. Both need excellent drainage.

Where does the boojum come from?

It grows on rocky slopes on the west coast of Baja California and in one small area of Sonora. Coastal humidity is high there. Rain is sporadic.

More plant watering guides

Hawaiian TiFilbertSpotted GumDove TreeRoyal PoincianaTriangle PalmMountain White GumRainbow Eucalyptus

Sources