How often to water silvery yarrow in California
In July in the Central Valley, established silvery yarrow 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. Silvery yarrow is a small, mat-forming perennial from the mountains of central and southeastern Europe. It makes a low mound of deeply cut, aromatic silver leaves, topped by flat clusters of small white flowers on short stems. Once settled it needs little water, and it dislikes waterlogged soil.
How often to water silvery yarrow, 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 2 to 3 inches down beside a young clump means it is ready for water
- Leaves turning almost white during a dry spell show the plant is short of water, though an established clump tolerates it
- Flower stems that wilt in afternoon heat, with dry soil below, call for a slow soak
- A clump that yellows and goes limp while the soil stays wet points to waterlogging, which this mountain yarrow dislikes
- White powdery patches on the leaves are powdery mildew, a known problem that extra water will not fix
How to water it
- Water at the base of the clump with drip or a watering can, keeping the silver leaves dry
- Soak until the top 6 to 8 inches of soil are moist, then let the top few inches dry before watering again
- Plant in soil that drains fast, such as a slope, a raised bed or a rock garden pocket
- Mulch around the clump with gravel rather than bark so the crown stays dry
- Widen the watered spot as the mat spreads toward its full width of about a foot
Through the seasons
Water a new planting regularly through its first summer, until its roots reach well into the surrounding soil. After that, silvery yarrow is drought-tolerant and needs only occasional deep soaks in summer. Its leaves stay through most winters, since it is evergreen to semi-evergreen. Flowers appear in late spring or summer, and cutting off spent clusters keeps more coming. WUCOLS rates it low water on the north-central coast, in the Central Valley, on the south coast and in South Inland. Winter rain covers the cool months on the coast and in the valley. WUCOLS marks it as not suited to the high desert or the low desert.
In pots
Silvery yarrow suits a shallow pot or trough, where its silver mat can spill over the rim. Use a gritty, fast-draining mix and a pot with open holes. Check the mix 1 to 2 inches down every few days in summer, and daily during inland heat waves. Water until it runs from the holes, then empty the saucer so the crown never sits wet. Full sun suits it, and light afternoon shade is fine in Central Valley heat. In winter, water only when the mix is dry well below the surface.
- A year
- 6.84 gal per sq ft
- Reference
- Sacramento climate table
- Counts
- Plant need, before sprinkler losses
Monthly water need by climate zone
Silvery Yarrow: 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 | 0.31 | – | – |
| Feb | 0.21 | 0.26 | 0.32 | 0.35 | – | – |
| Mar | 0.35 | 0.43 | 0.46 | 0.52 | – | – |
| Apr | 0.47 | 0.61 | 0.56 | 0.64 | – | – |
| May | 0.58 | 0.83 | 0.64 | 0.78 | – | – |
| Jun | 0.64 | 0.99 | 0.69 | 0.92 | – | – |
| Jul | 0.64 | 1.07 | 0.79 | 1 | – | – |
| Aug | 0.6 | 0.95 | 0.74 | 0.93 | – | – |
| Sep | 0.5 | 0.72 | 0.6 | 0.74 | – | – |
| Oct | 0.35 | 0.47 | 0.46 | 0.53 | – | – |
| Nov | 0.19 | 0.22 | 0.33 | 0.36 | – | – |
| Dec | 0.12 | 0.14 | 0.26 | 0.27 | – | – |
| Year | 4.8 | 6.84 | 6.2 | 7.37 | – | – |
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 silvery yarrow. 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
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 July
Lady's MantleAlchemilla mollislow water, Central Valley1.07 gal/sq ft in JulyTurn this into minutes on your water days
Every city page has a calculator that takes silvery yarrow, 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 silvery yarrow in summer?
In July, established silvery yarrow in loam needs a deep watering about every 14 days in the Central Valley, about every 18 days on the south coast and about every 14 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 does silvery yarrow need per day?
In July in the Central Valley, established silvery yarrow 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 silvery yarrow change across California?
Yes. WUCOLS rates silvery yarrow 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, low water in the South Inland zone, not suited to this region 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.
How big does silvery yarrow get?
It stays small, about 4 to 6 inches tall and 10 to 12 inches wide, with flower stems a little taller. It grows slowly and suits rock gardens, gravel gardens and the front of a border.
Should I deadhead silvery yarrow?
Yes. Removing spent flower clusters regularly prolongs flowering. Cut them back to the foliage, and do not add extra water to push new blooms.
Why are my silvery yarrow leaves turning white?
The foliage turns almost white in periods of drought. On an established plant this is a normal response, not an emergency. If the soil is dry several inches down and the stems also go limp, give a slow soak.
Does silvery yarrow attract bees?
Yes. The white flowers draw bees, butterflies and other beneficial insects. That makes it a good fit for a wildlife or gravel garden.
How do I divide silvery yarrow?
Divide it in spring. Lift the clump, split it into rooted pieces, and replant them at once. Water the divisions in and keep the soil lightly moist until new growth starts.
What pests bother silvery yarrow?
Aphids and powdery mildew are the problems most likely to show up. Neither is caused by a dry spell, so look the plant over closely before changing how you water.
More plant watering guides
Sources
- WUCOLS IV plant water use classification for Achillea clavennae, 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