WateringTimesWatering plan, $19
Coleogyne ramosissima, WUCOLS IV

How often to water blackbrush in California

In July in the South Inland zone, established blackbrush 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. Blackbrush is a tough native desert shrub that grows from California's deserts into Nevada, Arizona and Utah. It forms a twiggy mound 3 to 5 feet tall with light green leaves that drop under drought stress, and small yellow flowers. The bush looks black only when wet. It grows where little else will, sometimes in soil that looks like concrete.

ShrubCalifornia nativeRated for 2 of 6 zones

How often to water blackbrush, 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 blackbrush 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 dropping in summer heat is normal drought dormancy, not a reason to water
  • A young plant wilting in its first summer can take one deep soak
  • Yellowing and dieback after regular watering point to too much water
  • Fresh leaves after rain show the shrub is responding to moisture

How to water it

  • Give no regular water once established
  • Water a new plant only a few times in its first season
  • Plant in full sun in fast-draining, alkaline soil
  • Keep it far from lawns and irrigated beds
  • Use it in desert gardens and on hard, rocky ground

Through the seasons

Water a new plant a few times in its first season, then stop. Established shrubs live on very little rain and drop leaves in drought, regrowing when moisture returns. In the wild it grows where yearly rain is scant and the soil is poor and hard. WUCOLS rates blackbrush very low water in South Inland and in the high desert. WUCOLS marks it as not suited to the south coast, and has not evaluated it for the north-central coast, the Central Valley or the low desert.

In pots

Blackbrush is a desert shrub that rarely suits containers. A young plant can still live for a while in a large pot of gritty, alkaline, fast-draining mix in full sun. Water only when the mix is dry deep down, then let it drain completely. In summer, water sparingly. Never leave water in the saucer. In winter, rain is enough, and a dry spell does no harm.

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

WUCOLS lists Blackbrush as not evaluated for the Central Valley zone, so no monthly figure is computed here.

Monthly water need by climate zone

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

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan–––0.080.07–
Feb–––0.090.09–
Mar–––0.130.15–
Apr–––0.160.19–
May–––0.20.24–
Jun–––0.230.29–
Jul–––0.250.3–
Aug–––0.230.28–
Sep–––0.190.21–
Oct–––0.130.15–
Nov–––0.090.09–
Dec–––0.070.07–
Year–––1.842.13–

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 evaluated in the Central Valley, like blackbrush. Plants that drink alike can share one valve and one schedule.

Formosa Sugar PalmArenga englerinot rated, Central Valleyno Central Valley ratingChilean Feather BambooChusquea culeou (C. breviglumis)not rated, Central Valleyno Central Valley ratingGlaucous Scorpion VetchCoronilla valentina glaucanot rated, Central Valleyno Central Valley ratingWillowleaf CotoneasterCotoneaster salicifoliusnot rated, Central Valleyno Central Valley ratingMadagascar SagoCycas thouarsii (SHADE)not rated, Central Valleyno Central Valley ratingIrish HeathDaboecia cantabricanot rated, Central Valleyno Central Valley ratingButterfly PalmDypsis lutescens (Areca)not rated, Central Valleyno Central Valley ratingUmbrella BambooFargesia murielaenot rated, Central Valleyno Central Valley ratingBlue Fountain BambooFargesia nitida (Sinarundinaria nitida) (BAMBOO)not rated, Central Valleyno Central Valley ratingPrickly HeathGaultheria mucronata (Pernettya mucronata)not rated, Central Valleyno Central Valley ratingOtterbossieGossypium harknessiinot rated, Central Valleyno Central Valley ratingBox-leaved HollyIlex crenatanot rated, Central Valleyno Central Valley ratingBellyache BushJatropha gossypiifolianot rated, Central Valleyno Central Valley ratingMountain LaurelKalmia latifolianot rated, Central Valleyno Central Valley ratingBarbados CherryMalpighia glabranot rated, Central Valleyno Central Valley ratingSiberian CypressMicrobiota decussatanot 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 blackbrush, 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 blackbrush need per day?

In July in the South Inland zone, established blackbrush needs about 0.1 gallons a day for a plant 4 feet across and about 0.4 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 blackbrush change across California?

Yes. WUCOLS rates blackbrush separately for each of the six California climate zones: not evaluated in the North-Central Coastal zone, not evaluated in the Central Valley zone, not suited to this region in the South Coastal zone, very low water in the South Inland zone, very low water 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.

Why is it called blackbrush?

The twiggy bush looks black when wet. Dry, it shows light green leaves. The name comes from its look after rain.

Does blackbrush need water?

Once established it needs little or no irrigation. It grows where rainfall is very low. Overwatering harms it.

Where does blackbrush grow wild?

It grows in California's deserts and east into Nevada, Arizona and Utah. It forms part of creosote bush scrub and pinyon-juniper woodland. It thrives on poor soil.

Why did my blackbrush lose its leaves?

It is stress deciduous and drops leaves in drought. That is normal. New leaves follow rain.

Can blackbrush grow in hard soil?

Yes, it grows where nothing else will, even in soil that looks like concrete. It prefers alkaline soil. Drainage still matters.

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Sources