How often to water Jacob's rod in California
In July in the Central Valley, established Jacob's rod in loam needs a deep watering about every 14 days: about 1.5 gallons each time for a plant 2 feet across, about 0.8 gallons a week. Jacob's rod, also called king's spear or yellow asphodel, is a long-lived perennial from the eastern Mediterranean and nearby lands. In the wild it grows in dry grassland and stony places. Grassy, gray-green leaves form a low clump, and in mid to late spring leafy stems rise 3 to 4 feet with dense spikes of fragrant yellow flowers.
How often to water Jacob's rod, 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 6 inches down beside the clump in spring means Jacob's rod can take a deep drink
- Flower spikes coming up short after a very dry winter can follow too little water
- Leaves yellowing in summer after seed set is its normal rest
- A soft, rotting crown in heavy, wet soil points to poor drainage
How to water it
- Water occasionally to infrequently once established
- Soak deeply, then let the soil dry well between waterings
- Plant in full sun or part shade in well-drained soil
- Mulch the crown where winters are cold
- Leave the seedpods for their brown color, or cut them for arrangements
Through the seasons
Water new plants regularly until roots establish. Once settled, it is fairly drought tolerant in coastal gardens and needs only occasional to infrequent water. Spikes bloom in mid to late spring, round green seedpods ripen to brown, and the clump spreads slowly by rhizomes. WUCOLS rates Jacob's rod low water on the north-central coast, in the Central Valley and on the south coast. WUCOLS has not evaluated it for South Inland, the high desert or the low desert.
In pots
Jacob's rod can grow in a large, deep pot on a sunny patio, where its tall spikes make a show. Use a gritty, well-drained mix. Water when the top couple of inches are dry, then let it drain. In spring, check pots every few days while spikes grow. Never leave water in the saucer. After bloom, cut back on watering. In winter, rain is usually enough for an outdoor pot.
- A year
- 6.84 gal per sq ft
- Reference
- Sacramento climate table
- Counts
- Plant need, before sprinkler losses
Monthly water need by climate zone
Jacob's Rod: gallons per square foot per month, by WUCOLS climate zone
| Month | N. Coast | C. Valley | S. Coast | S. Inland | Hi Desert | Lo Desert |
|---|---|---|---|---|---|---|
| Jan | 0.15 | 0.16 | 0.31 | – | – | – |
| Feb | 0.21 | 0.26 | 0.32 | – | – | – |
| Mar | 0.35 | 0.43 | 0.46 | – | – | – |
| Apr | 0.47 | 0.61 | 0.56 | – | – | – |
| May | 0.58 | 0.83 | 0.64 | – | – | – |
| Jun | 0.64 | 0.99 | 0.69 | – | – | – |
| Jul | 0.64 | 1.07 | 0.79 | – | – | – |
| Aug | 0.6 | 0.95 | 0.74 | – | – | – |
| Sep | 0.5 | 0.72 | 0.6 | – | – | – |
| Oct | 0.35 | 0.47 | 0.46 | – | – | – |
| Nov | 0.19 | 0.22 | 0.33 | – | – | – |
| Dec | 0.12 | 0.14 | 0.26 | – | – | – |
| Year | 4.8 | 6.84 | 6.2 | – | – | – |
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 low water in the Central Valley, like Jacob's rod. Plants that drink alike can share one valve and one schedule.
AgapanthusAgapanthus orientalislow water, Central Valley1.07 gal/sq ft in July
GeraniumsPelargonium x hortorum and cvs.low water, Central Valley1.07 gal/sq ft in July
SalviaSalvia greggii ssp., cvs. & hybridslow water, Central Valley1.07 gal/sq ft in July
IrisesIris germanicalow water, Central Valley1.07 gal/sq ft in July
SucculentsEcheveria spp. & cvs.low water, Central Valley1.07 gal/sq ft in July
Russian SagePerovskia spp. & cvs.low water, Central Valley1.07 gal/sq ft in July
YarrowAchillea millefolium (non-native hybrids)low water, Central Valley1.07 gal/sq ft in July
Mountain AlyssumAlyssum montanumlow water, Central Valley1.07 gal/sq ft in July
Silver SageSalvia argentealow water, Central Valley1.07 gal/sq ft in July
Purple MulleinVerbascum phoeniceumlow water, Central Valley1.07 gal/sq ft in July
Silvery YarrowAchillea clavennaelow water, Central Valley1.07 gal/sq ft in July
Fern Leaf YarrowAchillea filipendulinalow water, Central Valley1.07 gal/sq ft in July
California Native YarrowAchillea millefolium (CA native cultivars)low water, Central Valley1.07 gal/sq ft in July
Woolly YarrowAchillea tomentosalow water, Central Valley1.07 gal/sq ft in July
Perennial HollyhockAlcea rosea cvs.low water, Central Valley1.07 gal/sq ft in July
Mountain Lady's MantleAlchemilla alpinalow water, Central Valley1.07 gal/sq ft in JulyTurn this into minutes on your water days
Every city page has a calculator that takes Jacob's rod, 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 Jacob's rod in summer?
In July, established Jacob's rod in loam needs a deep watering about every 14 days in the Central Valley and about every 18 days on the south coast. 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 Jacob's rod need per day?
In July in the Central Valley, established Jacob's rod needs about 0.1 gallons a day for a plant 2 feet across and about 0.4 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 Jacob's rod change across California?
Yes. WUCOLS rates Jacob's rod separately for each of the six California climate zones: low water in the North-Central Coastal zone, low water in the Central Valley zone, low water 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 Jacob's rod drought tolerant?
Near the coast, an established clump gets by on little water. It needs only occasional soaks there. Young plants need more.
When does Jacob's rod bloom?
It blooms in mid to late spring. Dense spikes of fragrant yellow flowers top 3 to 4 foot stems. Seedpods follow.
Does Jacob's rod spread?
It spreads slowly by rhizomes. It is long-lived. Divide large clumps if needed.
How cold hardy is Jacob's rod?
Its roots are hardy well below 0 degrees F when mulched. Cold is rarely a problem in California. Drainage matters more.
Where does Jacob's rod grow wild?
It grows in dry grassland and rocky, stony places, often on limestone. Its home stretches from the eastern Mediterranean to western Asia. That explains its taste for drainage.
More plant watering guides
Sources
- WUCOLS IV plant water use classification for Asphodeline lutea, 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