WateringTimesWatering plan, $19
Erigeron karvinskianus, WUCOLS IV

How often to water Mexican fleabane in California

In July in the Central Valley, established Mexican fleabane 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. Mexican fleabane, often sold as Santa Barbara daisy, is a low, sprawling perennial from Mexico and Central and South America. Small white daisies with yellow centers, often blushed pink, appear almost all year. It loves cool coastal sun and tolerates poor soil and drought. Summer heat inland makes it stall until fall.

PerennialUC Arboretum All-StarRated for 6 of 6 zones

How often to water Mexican fleabane, month by month

Your city
Plant width
2 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 Mexican fleabane 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 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.

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 plant width

A shrub with its width marked from one side to the other and the circle under it shaded blue

Measure across the plant, from the tips of the leaves on one side to the tips on the other.

Water the whole area the plant covers, shown in blue. The gallons here cover that area.

A wider plant means more gallons each watering, not more waterings. While it is young, measure again each spring.

How to tell it needs water

  • Mexican fleabane stems going limp in heat while the soil is dry an inch or two down mean it needs water
  • A summer pause in bloom inland is a heat response, not always thirst
  • Seedlings spreading well beyond the planting point to more water than it needs
  • Matted, leggy growth calls for a cutback, not extra water

How to water it

  • Water at the base when the top inch or two of soil dries
  • Plant in cool sun to light shade in well-drained soil
  • Shear it back hard now and then to renew growth
  • Keep water modest to limit reseeding
  • Tuck it into wall cracks or along edges where it can cascade

Through the seasons

Water new plants regularly until they knit together. On the coast and in the Central Valley it needs little water once established, and winter rain covers the cool months. In South Inland and the deserts, summer heat calls for steadier water and some shade. It may shut down in summer heat, then bloom again in fall until hard frost. WUCOLS rates Mexican fleabane low water on the north-central coast, in the Central Valley and on the south coast. South Inland, the high desert and the low desert carry the same moderate water rating.

In pots

Mexican fleabane spills beautifully over the edge of a large pot or wall planter. Use a well-drained mix. Water when the top inch is dry, until it runs from the base. In inland summer heat, check every day or two and give afternoon shade. Empty the saucer. Cut it back when stems get matted. In winter, water only when the mix dries, and protect it below about 15 degrees F.

1 Your climate zone six WUCOLS zones, each from its own reference city
1.07gal per sq ft in JulyLow water use in the Central Valley zone
A year
6.84 gal per sq ft
Reference
Sacramento climate table
Counts
Plant need, before sprinkler losses
0.761.52.33.00.16JAN0.26FEB0.43MAR0.61APR0.83MAY0.99JUN1.07JUL0.95AUG0.72SEP0.47OCT0.22NOV0.14DEC0.761.52.33.00.16JFM0.61AMJ1.07JAS0.47OND
Gallons per square foot per month, Central Valley. Peak 1.07 in Jul, 6.84 a year.

Monthly water need by climate zone

Mexican Fleabane: gallons per square foot per month, by WUCOLS climate zone

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.150.160.310.780.740.78
Feb0.210.260.320.870.930.93
Mar0.350.430.461.31.461.52
Apr0.470.610.561.611.891.95
May0.580.830.641.952.392.45
Jun0.640.990.692.292.852.79
Jul0.641.070.792.513.042.85
Aug0.60.950.742.332.792.6
Sep0.50.720.61.862.142.08
Oct0.350.470.461.331.461.49
Nov0.190.220.330.90.930.96
Dec0.120.140.260.680.650.68
Year4.86.846.218.4121.2721.08

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 low water in the Central Valley, like Mexican fleabane. Plants that drink alike can share one valve and one schedule.

AgapanthusAgapanthus orientalislow water, Central Valley1.07 gal/sq ft in JulyGeraniumsPelargonium x hortorum and cvs.low water, Central Valley1.07 gal/sq ft in JulySalviaSalvia greggii ssp., cvs. & hybridslow water, Central Valley1.07 gal/sq ft in JulyIrisesIris germanicalow water, Central Valley1.07 gal/sq ft in JulySucculentsEcheveria spp. & cvs.low water, Central Valley1.07 gal/sq ft in JulyRussian SagePerovskia spp. & cvs.low water, Central Valley1.07 gal/sq ft in JulyYarrowAchillea millefolium (non-native hybrids)low water, Central Valley1.07 gal/sq ft in JulyMountain AlyssumAlyssum montanumlow water, Central Valley1.07 gal/sq ft in JulySilver SageSalvia argentealow water, Central Valley1.07 gal/sq ft in JulyPurple MulleinVerbascum phoeniceumlow water, Central Valley1.07 gal/sq ft in JulySilvery YarrowAchillea clavennaelow water, Central Valley1.07 gal/sq ft in JulyFern Leaf YarrowAchillea filipendulinalow water, Central Valley1.07 gal/sq ft in JulyCalifornia Native YarrowAchillea millefolium (CA native cultivars)low water, Central Valley1.07 gal/sq ft in JulyWoolly YarrowAchillea tomentosalow water, Central Valley1.07 gal/sq ft in JulyPerennial HollyhockAlcea rosea cvs.low water, Central Valley1.07 gal/sq ft in JulyMountain Lady's MantleAlchemilla alpinalow water, Central Valley1.07 gal/sq ft in July
Minutes for your sprinklers

Turn this into minutes on your water days

Every city page has a calculator that takes Mexican fleabane, 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 Mexican fleabane in summer?

In July, established Mexican fleabane 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 6 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 Mexican fleabane need per day?

In July in the Central Valley, established Mexican fleabane 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 Mexican fleabane change across California?

Yes. WUCOLS rates Mexican fleabane 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, moderate water in the South Inland zone, moderate 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.

Is Mexican fleabane the same as Santa Barbara daisy?

Yes, both names refer to Erigeron karvinskianus. It is also sold as seaside daisy. The flowers are small white daisies with yellow centers.

Is Mexican fleabane invasive?

It self-sows and spreads by rhizomes, sometimes aggressively. Moderate water makes it more likely to spread. Pull seedlings where you do not want them.

When does Mexican fleabane bloom?

It blooms almost all year in mild climates. Inland heat can stop it in summer. It picks up again when fall turns cool.

Does Mexican fleabane attract bees?

Yes, the flowers draw bees and tiny beneficial flies and wasps. That makes it a good edging for vegetable beds. It blooms over a long season.

How do I keep Mexican fleabane tidy?

Cut it down periodically to renew it. Fresh growth fills in after the cut. Water lightly afterward.

More plant watering guides

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Sources