WateringTimesWatering plan, $19
Spartium junceum, WUCOLS IV

How often to water Spanish broom in California

In July in the Central Valley, established Spanish broom 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. Spanish broom is a fast growing shrub to about 10 feet, built of slender green, rush-like stems that hold few leaves for long. Fragrant yellow pea flowers cover the shoots in summer, and the pods later burst open with an audible crack. It thrives on dry, poor, rocky soil in full sun, and it is a high-impact invasive plant in California wildlands.

ShrubRated for 5 of 6 zones

How often to water Spanish broom, 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 Spanish broom 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

  • Green stems turning dull and shriveled after a long, hot dry spell signal that a young plant needs a deep soak
  • Soil dry well below the surface is normal for an established plant and is not a reason to water
  • Leaves dropping in late spring is normal, since its small leaves last only a few months
  • Yellowing, soft stems near the base in soil that stays wet can indicate overwatering
  • Seedlings sprouting around the shrub show that it is spreading, not that it needs more water

How to water it

  • Water only a new planting, soaking the root ball and the soil around it until roots take hold
  • Once established, give it at most an occasional deep soak during a prolonged drought
  • Plant in full sun in lean, rocky or sandy soil that drains well, since it will not grow in shade
  • Keep it out of irrigated beds and lawns, since it needs far less water than most garden plants
  • Remove seed pods before they ripen and burst so new plants do not spring up nearby

Through the seasons

A new Spanish broom needs occasional deep watering through its first summer while roots establish. After that it lives on rainfall in most years and has good drought tolerance. Its small leaves drop by late spring, and the green stems carry on through the dry season while flowers and pods form. WUCOLS rates Spanish broom very low water on the north-central coast, in the Central Valley and on the south coast. It holds the same very low water rating in South Inland and the high desert. WUCOLS marks it as not suited to the low desert. Pull seedlings promptly to keep it from spreading.

In pots

Spanish broom can grow in a large container, where its spread is easier to manage. Use a gritty, fast draining mix and a pot with open holes. Check the mix every few days in summer heat and water only when it is dry several inches down. Let water drain through, then empty the saucer. Keep the pot in full sun, and snip off seed pods before they split. In winter, water rarely, if at all, while rain does the job.

1 Your climate zone six WUCOLS zones, each from its own reference city
0.27gal per sq ft in JulyVery low water use in the Central Valley zone
A year
1.71 gal per sq ft
Reference
Sacramento climate table
Counts
Plant need, before sprinkler losses
0.070.150.220.300.04JAN0.07FEB0.11MAR0.15APR0.21MAY0.25JUN0.27JUL0.24AUG0.18SEP0.12OCT0.06NOV0.03DEC0.070.150.220.300.04JFM0.15AMJ0.27JAS0.12OND
Gallons per square foot per month, Central Valley. Peak 0.27 in Jul, 1.71 a year.

Monthly water need by climate zone

Spanish Broom: gallons per square foot per month, by WUCOLS climate zone

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.040.040.080.080.07–
Feb0.050.070.080.090.09–
Mar0.090.110.110.130.15–
Apr0.120.150.140.160.19–
May0.150.210.160.20.24–
Jun0.160.250.170.230.29–
Jul0.160.270.20.250.3–
Aug0.150.240.190.230.28–
Sep0.120.180.150.190.21–
Oct0.090.120.110.130.15–
Nov0.050.060.080.090.09–
Dec0.030.030.070.070.07–
Year1.21.711.551.842.13–

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 very low water in the Central Valley, like Spanish broom. Plants that drink alike can share one valve and one schedule.

OleanderNerium oleander ssp. & cvs.very low water, Central Valley0.27 gal/sq ft in JulyAgaveAgave americana (and thick-leaved relatives)very low water, Central Valley0.27 gal/sq ft in JulyCactusOpuntia spp. & cvs. (CA natives and non-natives)very low water, Central Valley0.27 gal/sq ft in JulyPearl AcaciaAcacia podalyriifoliavery low water, Central Valley0.27 gal/sq ft in JulyBig SagebrushArtemisia tridentatavery low water, Central Valley0.27 gal/sq ft in JulyCalifornia Scrub OakQuercus berberidifoliavery low water, Central Valley0.27 gal/sq ft in JulyNuttall's Scrub OakQuercus dumosavery low water, Central Valley0.27 gal/sq ft in JulyCreosote BushLarrea tridentata ssp. & cvs.very low water, Central Valley0.27 gal/sq ft in JulyPurple SageSalvia leucophylla ssp. & cvs.very low water, Central Valley0.27 gal/sq ft in JulyBlack SageSalvia mellifera ssp. & cvs.very low water, Central Valley0.27 gal/sq ft in JulyBeaked YuccaYucca rostrata ssp. & cvs.very low water, Central Valley0.27 gal/sq ft in JulyToyonHeteromeles arbutifolia ssp. & cvs.very low water, Central Valley0.27 gal/sq ft in JulyFox Tail AgaveAgave attenuata (and thin-leaved relatives)very low water, Central Valley0.27 gal/sq ft in JulySaltbushAtriplex (CA native species) & ssp. & cvs.very low water, Central Valley0.27 gal/sq ft in JulyOak TreesQuercus agrifoliavery low water, Central Valley0.27 gal/sq ft in JulySalt CedarTamarix aphyllavery low water, Central Valley0.27 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 Spanish broom, 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 Spanish broom in summer?

In July, established Spanish broom in loam needs a deep watering about once a month or less in the Central Valley, 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 Spanish broom need per day?

In July in the Central Valley, established Spanish broom 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 Spanish broom change across California?

Yes. WUCOLS rates Spanish broom separately for each of the six California climate zones: very low water in the North-Central Coastal zone, very low water in the Central Valley zone, very low water in the South Coastal zone, very low water in the South Inland zone, very low water 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.

Is Spanish broom invasive in California?

Yes. It is rated a high-impact invasive plant in California, where it forms dense stands that crowd out native plants. It produces copious seed and resprouts from the root crown when cut. Where it takes over, it also raises fire hazards.

Why does my Spanish broom have almost no leaves?

Its small leaves last only a few months and fall away by late spring. The slender green stems carry the plant for the rest of the year. A leafless look in summer is normal and not a sign of thirst.

Why do I hear popping from my Spanish broom?

In late summer the ripe seed pods burst open with an audible crack, flinging seed away from the plant. Cutting off pods before they ripen limits new seedlings. Watering has no effect on this.

How do I remove Spanish broom?

Pull young plants with their roots, and cut larger shrubs at the base before digging out the root crown. It resprouts from the crown if only cut, so return to remove regrowth. Keep pulling seedlings as they appear.

Can Spanish broom grow by the ocean?

Yes. It tolerates seaside exposure and poor, rocky soil in full sun. It will not grow in shade.

More plant watering guides

Giant ScillaInterior Live OakBlue OakNuttall's Scrub OakVariegated Century PlantDesert AgaveThread Leaf AgavePalmer Agave

Sources