WateringTimesWatering plan, $19
Tecoma stans ssp. & cvs., WUCOLS IV

How often to water yellow bells in California

In July on the north-central coast, established yellow bells in loam need a deep soak only about once a month or less: about 55 gallons each time under a 10 foot canopy. Yellow bells are fast, evergreen shrubs or small trees with bright green, toothed leaflets. Clusters of yellow trumpet flowers weigh the branch tips into arches in flushes from spring into fall. They need summer heat and good drainage, and established plants take dry spells well outside the low desert.

ShrubTreeRated for 5 of 6 zones

How often to water yellow bells, 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 yellow bells 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 3 to 4 inches down around yellow bells in summer signals that the shrubs need a deep soak
  • Leaves wilting and flower clusters dropping early in a heat spell can mean the root zone has dried out
  • Blackened stem tips and leaf drop after a cold night are frost damage, not thirst, and growth often returns in spring
  • Yellowing leaves over soil that stays wet point to poor drainage, since these shrubs need well-drained ground
  • Fewer blooms in a cool coastal summer reflect a lack of heat more than a lack of water

How to water it

  • Water at the base of the shrub with drip or a slow hose, wetting a ring out to the edge of the branches
  • Soak the soil about 18 inches deep, then let the top few inches dry before the next soak
  • Plant in full sun in soil that drains freely, building a low mound where clay holds water
  • Use a thin layer of bark or gravel mulch, keeping it a few inches back from the main stems
  • Move emitters outward as the shrub widens, since older plants spread 10 feet or more

Through the seasons

Newly planted yellow bells need regular deep soakings through their first summer while roots spread. Established shrubs need far less, though the low desert's long heat calls for steadier summer water. They stay evergreen in mild winters and flower in flushes from spring into fall, with long, bean-like pods after. A cold snap can kill back the smaller stems, and growth returns in spring. Winter rain covers the cool months on the coast. WUCOLS rates yellow bells low water on the north-central coast, on the south coast, in South Inland and in the high desert. It rates moderate water in the low desert. WUCOLS marks yellow bells as not suited to the Central Valley.

In pots

Compact cultivars of yellow bells, which stay 6 to 8 feet tall, suit a large container on a hot patio. Check the mix 2 to 3 inches down every few days in summer heat, and daily in the low desert. Soak until water drains from the holes, then empty the saucer. In winter, water only when the mix has dried well down. Move the pot against a warm wall before a cold night, since frost damages the stems.

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

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

Monthly water need by climate zone

Yellow Bells: gallons per square foot per month, by WUCOLS climate zone

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.15–0.310.310.30.78
Feb0.21–0.320.350.370.93
Mar0.35–0.460.520.581.52
Apr0.47–0.560.640.761.95
May0.58–0.640.780.952.45
Jun0.64–0.690.921.142.79
Jul0.64–0.7911.222.85
Aug0.6–0.740.931.122.6
Sep0.5–0.60.740.862.08
Oct0.35–0.460.530.581.49
Nov0.19–0.330.360.370.96
Dec0.12–0.260.270.260.68
Year4.8–6.27.378.5121.08

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 yellow bells. 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 yellow bells, 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 yellow bells in summer?

In July, established yellow bells in loam need a deep watering about every 27 days on the south coast and about every 22 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 do yellow bells need per day?

In July on the north-central coast, established yellow bells need about 1.6 gallons a day under a 10 foot canopy and about 6.5 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 yellow bells change across California?

Yes. WUCOLS rates yellow bells separately for each of the six California climate zones: low water in the North-Central Coastal zone, not suited to this region in the Central Valley zone, low water in the South Coastal zone, low water in the South Inland zone, low water in the High and Intermediate Desert zone, moderate 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 are my yellow bells not blooming?

They need summer heat and full sun to flower well, so a cool or shaded spot gives fewer blooms. Flowers come in flushes, with quiet spells between them. Extra water will not make up for missing heat or sun.

Will yellow bells survive frost?

Hardiness is around 25 to 30 degrees F. Older plants in Southern California came back after a freeze near 18 degrees, though the smaller stems were badly damaged. Wait for spring growth before cutting back frozen wood.

Should I remove yellow bells seedpods?

The long, bean-like pods follow the flowers and release seeds that can sprout around the garden. Yellow bells can be weedy or invasive, so trimming spent clusters limits seedlings. Removing pods does not change how much water the shrubs need.

Can yellow bells be grown as a tree?

Yes. The shrub can be trained into a small tree 15 to 20 feet tall, and its trunk bark turns light brown and corky with age. Water a tree-form plant the same way, under the outer branches.

Are yellow bells drought tolerant?

Established plants take dry spells well in most of the zones WUCOLS rates. In the low desert they still need regular deep summer soaks. Young plants need steady water until their roots spread.

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Sources