How often to water bellyache bush in California
In July in the low desert, established bellyache bush in loam needs a deep watering about every 8 days: about 8.8 gallons each time for a plant 4 feet across, about 8.1 gallons a week. Bellyache bush is a tropical American shrub, usually 6 to 10 feet tall, with lobed leaves often tinged red, purple or bronze. Clusters of small red to purple flowers appear much of the year when moisture allows. Every part is poisonous, especially the seeds. It drops its leaves in dry spells and spreads aggressively by seed in warm climates.
How often to water bellyache bush, month by month
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.
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.
How to tell it needs water
- Soil dry 3 inches down beside the shrub in summer signals bellyache bush can take a soak
- Leaves yellowing and dropping in a long dry spell is its normal response to drought
- Flowering stopping in hot, dry weather can follow a dry root zone
- Soft, rotting stems at the base over soggy soil suggest overwatering
How to water it
- Water at the base with drip or a slow hose, keeping sap off your skin when you work nearby
- Soak several inches down, then let the soil dry before the next soak
- Plant in well-drained soil, away from children's play areas
- Remove seed capsules before they split to stop seedlings
- Keep it away from washes and wild areas where seed can spread
Through the seasons
Water a new plant regularly until it roots in. It grows and flowers whenever moisture allows and drops its leaves during dry seasons. Plants can live more than 20 years. Its rapid seed set and spread make it a serious weed in warm regions abroad. In the low desert, WUCOLS rates bellyache bush moderate water. WUCOLS marks it as not suited to the north-central coast or the high desert. It has not evaluated it for the Central Valley, the south coast or South Inland.
In pots
Bellyache bush can be grown in a container, which helps contain its seeds. Use a well-drained mix and water when the top couple of inches dry, letting it drain. In desert heat, a pot can dry in a day or two. Empty the saucer each time. Pick off seed capsules before they split. Wear gloves, since the sap irritates skin. In cold weather, move the pot under cover.
- A year
- no figure
- Reference
- Sacramento climate table
- Counts
- Plant need, before sprinkler losses
WUCOLS lists Bellyache Bush as not evaluated for the Central Valley zone, so no monthly figure is computed here.
Monthly water need by climate zone
Bellyache Bush: gallons per square foot per month, by WUCOLS climate zone
| Month | N. Coast | C. Valley | S. Coast | S. Inland | Hi Desert | Lo Desert |
|---|---|---|---|---|---|---|
| Jan | – | – | – | – | – | 0.78 |
| Feb | – | – | – | – | – | 0.93 |
| Mar | – | – | – | – | – | 1.52 |
| Apr | – | – | – | – | – | 1.95 |
| May | – | – | – | – | – | 2.45 |
| Jun | – | – | – | – | – | 2.79 |
| Jul | – | – | – | – | – | 2.85 |
| Aug | – | – | – | – | – | 2.6 |
| Sep | – | – | – | – | – | 2.08 |
| Oct | – | – | – | – | – | 1.49 |
| Nov | – | – | – | – | – | 0.96 |
| Dec | – | – | – | – | – | 0.68 |
| Year | – | – | – | – | – | 21.08 |
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 evaluated in the Central Valley, like bellyache bush. Plants that drink alike can share one valve and one schedule.
Formosa Sugar PalmArenga englerinot rated, Central Valleyno Central Valley rating
Chilean Feather BambooChusquea culeou (C. breviglumis)not rated, Central Valleyno Central Valley rating
BlackbrushColeogyne ramosissimanot rated, Central Valleyno Central Valley rating
Glaucous Scorpion VetchCoronilla valentina glaucanot rated, Central Valleyno Central Valley rating
Willowleaf CotoneasterCotoneaster salicifoliusnot rated, Central Valleyno Central Valley rating
Madagascar SagoCycas thouarsii (SHADE)not rated, Central Valleyno Central Valley rating
Irish HeathDaboecia cantabricanot rated, Central Valleyno Central Valley rating
Butterfly PalmDypsis lutescens (Areca)not rated, Central Valleyno Central Valley rating
Umbrella BambooFargesia murielaenot rated, Central Valleyno Central Valley rating
Blue Fountain BambooFargesia nitida (Sinarundinaria nitida) (BAMBOO)not rated, Central Valleyno Central Valley rating
Prickly HeathGaultheria mucronata (Pernettya mucronata)not rated, Central Valleyno Central Valley rating
OtterbossieGossypium harknessiinot rated, Central Valleyno Central Valley rating
Box-leaved HollyIlex crenatanot rated, Central Valleyno Central Valley rating
Mountain LaurelKalmia latifolianot rated, Central Valleyno Central Valley rating
Barbados CherryMalpighia glabranot rated, Central Valleyno Central Valley rating
Siberian CypressMicrobiota decussatanot rated, Central Valleyno Central Valley ratingTurn this into minutes on your water days
Every city page has a calculator that takes bellyache 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 bellyache bush need per day?
In July in the low desert, established bellyache bush needs about 1.2 gallons a day for a plant 4 feet across and about 4.6 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 bellyache bush change across California?
Yes. WUCOLS rates bellyache bush separately for each of the six California climate zones: not suited to this region in the North-Central Coastal zone, not evaluated in the Central Valley zone, not evaluated in the South Coastal zone, not evaluated in the South Inland zone, not suited to this region 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.
Is bellyache bush poisonous?
Yes, all parts are poisonous to people and animals, and the seeds are the most toxic. Symptoms include abdominal pain, vomiting and diarrhea. Keep it far from children and pets.
Why is it called bellyache bush?
The name comes from the severe stomach upset caused by eating its seeds or other parts. It is sometimes confused with castor bean. Never eat any part of it.
Is bellyache bush invasive?
It forms dense thickets and is a declared weed in parts of Australia. It spreads mainly by seed ejected from splitting capsules. Remove capsules before they open.
Why did my bellyache bush lose its leaves?
It is deciduous in dry seasons and drops leaves when the soil dries. A deep soak brings new growth in warm weather. Leaf drop alone is not a sign it is dying.
Can I touch bellyache bush?
Touching the sap can irritate skin. Wear gloves and long sleeves when pruning. Wash hands after handling.
More plant watering guides
Sources
- WUCOLS IV plant water use classification for Jatropha gossypiifolia, the University of California survey California agencies use for landscape plan reviewRead August 23, 2026 on wucols.ucdavis.edu
- Model Water Efficient Landscape Ordinance, adopted text and appendices, effective 2025-01-02 · monthly reference evapotranspiration per city, Appendix CRead August 23, 2026 on water.ca.gov/-/media/DWR-Website/Web-Pages/Programs/Water-Use-And-Efficiency/MWELO-Rulemaking/Final-MWELO-Text-and-Appendices_20250103.pdf
- UC Statewide IPM Program, irrigation scheduling using evapotranspirationRead September 30, 2026 on ipm.ucanr.edu/PMG/GARDEN/ENVIRON/evap.html
- Shaw and Pittenger, Landscape Irrigation System Evaluation and Management, UC Cooperative Extension, 2009Read September 30, 2026 on ucanr.edu/sites/default/files/2013-02/160836.pdf
- Pittenger, Water Management in Gardens and Landscapes, UC Riverside, 2017Read September 30, 2026 on ucanr.edu/sites/default/files/2017-03/258022.pdf