How often to water serpentine sunflower in California
In July on the north-central coast, established serpentine sunflower in loam needs a deep watering about every 9 days: about 1.5 gallons each time for a plant 2 feet across, about 1.1 gallons a week. Serpentine sunflower, also called Bolander's sunflower, is a California native wildflower that stands upright and branching, often around 3 feet tall. Bright yellow flower heads with dark centers open from midsummer into early fall and draw native bees. In the wild it grows on harsh serpentine, clay or rocky soils, and it tolerates drought, though it grows taller with some water.
How often to water serpentine sunflower, 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 foot 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 around young plants in early summer signals serpentine sunflower needs a soak
- Leaves drooping through the afternoon before buds open can indicate thirst
- Short, early-flowering plants on a dry site reflect lean conditions rather than a crisis
- Yellowing lower leaves and stem bases rotting in soggy soil point to overwatering
How to water it
- Water seedlings at their base with a gentle hose until they are well rooted
- Soak several inches down, then let the soil dry before the next soak
- Plant or sow in full sun in lean, well-drained soil, including clay or rocky ground
- Skip fertilizer and rich amendments, which are not needed
- Leave some seed heads to ripen if you want plants next year
Through the seasons
Sow or plant in spring and keep seedlings moist until they root in. Growth speeds up as days warm, and flowers open from midsummer into early fall. Plants on dry, poor soil stay short, while those with average water and deep soil can top 5 feet. It is usually grown as an annual, so plants die back after seed sets. On the north-central coast, WUCOLS rates serpentine sunflower moderate water. WUCOLS has not evaluated it for the Central Valley, the south coast, South Inland, the high desert or the low desert.
In pots
Serpentine sunflower can grow in a deep pot of lean, gritty mix in full sun. Check the mix 2 inches down and water once it is dry, letting it drain freely. In summer heat, a pot can dry in a day or two. Empty the saucer after watering. Stake tall stems in wind. After seed heads ripen in fall, the plant is done, so save seed and refill the pot in spring.
- A year
- no figure
- Reference
- Sacramento climate table
- Counts
- Plant need, before sprinkler losses
WUCOLS lists Serpentine Sunflower as not evaluated for the Central Valley zone, so no monthly figure is computed here.
Monthly water need by climate zone
Serpentine Sunflower: gallons per square foot per month, by WUCOLS climate zone
| Month | N. Coast | C. Valley | S. Coast | S. Inland | Hi Desert | Lo Desert |
|---|---|---|---|---|---|---|
| Jan | 0.37 | – | – | – | – | – |
| Feb | 0.53 | – | – | – | – | – |
| Mar | 0.87 | – | – | – | – | – |
| Apr | 1.18 | – | – | – | – | – |
| May | 1.46 | – | – | – | – | – |
| Jun | 1.61 | – | – | – | – | – |
| Jul | 1.61 | – | – | – | – | – |
| Aug | 1.49 | – | – | – | – | – |
| Sep | 1.24 | – | – | – | – | – |
| Oct | 0.87 | – | – | – | – | – |
| Nov | 0.47 | – | – | – | – | – |
| Dec | 0.31 | – | – | – | – | – |
| Year | 12 | – | – | – | – | – |
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 serpentine sunflower. Plants that drink alike can share one valve and one schedule.
Lilyleaf LadybellsAdenophora liliifolianot rated, Central Valleyno Central Valley rating
ArnicaArnica montananot rated, Central Valleyno Central Valley rating
Frilly BergeniaBergenia ciliatanot rated, Central Valleyno Central Valley rating
Cabbage on a StickBrighamia insignisnot rated, Central Valleyno Central Valley rating
Basket PlantCallisia fragransnot rated, Central Valleyno Central Valley rating
Forest SedgeCarex sylvaticanot rated, Central Valleyno Central Valley rating
Umbrella DracaenaDianella ensifolianot rated, Central Valleyno Central Valley rating
Rusty FoxgloveDigitalis ferrugineanot rated, Central Valleyno Central Valley rating
Big-Flowered FoxgloveDigitalis grandifloranot rated, Central Valleyno Central Valley rating
Woolly FoxgloveDigitalis lanatanot rated, Central Valleyno Central Valley rating
Sunset FoxgloveDigitalis obscuranot rated, Central Valleyno Central Valley rating
Male FernDryopteris filix-masnot rated, Central Valleyno Central Valley rating
Alpine Sea HollyEryngium alpinumnot rated, Central Valleyno Central Valley rating
Purple SpurgeEuphorbia dulcisnot rated, Central Valleyno Central Valley rating
Queen of the MeadowFilipendula ulmarianot rated, Central Valleyno Central Valley rating
DropwortFilipendula vulgaris (Filipendula hexapetala)not rated, Central Valleyno Central Valley ratingTurn this into minutes on your water days
Every city page has a calculator that takes serpentine sunflower, 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 serpentine sunflower need per day?
In July on the north-central coast, established serpentine sunflower needs about 0.2 gallons a day for a plant 2 feet across and about 0.7 gallons a day for a plant 4 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 serpentine sunflower change across California?
Yes. WUCOLS rates serpentine sunflower separately for each of the six California climate zones: moderate water 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 evaluated 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.
Is serpentine sunflower native to California?
Yes, it is native to California and reaches just beyond the border into Oregon. It grows in foothill woodland, chaparral and pine forest. It is often found on serpentine soils.
Does serpentine sunflower need serpentine soil?
No, it grows on many soil types, including clay and rocky ground. Serpentine is simply one of the harsh soils it tolerates. Good drainage and full sun matter more.
How tall does serpentine sunflower get?
On harsh soils it stays short, sometimes under 3 feet. In deep, watered garden soil it can grow over 5 feet. Water controls its size more than its survival.
Is serpentine sunflower good for bees?
Yes, its flowers attract native bumble bees and other pollinators. Bloom lasts a couple of months in summer. Water in the morning so flowers stay dry.
Does serpentine sunflower come back each year?
It is usually grown as an annual and returns from seed. Let some heads ripen and drop seed. Pull extra seedlings in spring.
More plant watering guides
Sources
- WUCOLS IV plant water use classification for Helianthus bolanderi, 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