WateringTimesWatering plan, $19
Hibiscus lasiocarpus, WUCOLS IV

How often to water California hibiscus in California

In July in the Central Valley, established California hibiscus in loam needs a deep watering about every 5 days: about 1.5 gallons each time for a plant 2 feet across, about 1.9 gallons a week. California hibiscus, or woolly rose mallow, is a rare native of freshwater marshes, pond edges and stream banks in the Sacramento and San Joaquin valleys. Hairy stems rise from rhizomes to 3 to 6 feet, with heart-shaped, toothed leaves. Its large white flowers have a rose-red center, and it needs moist ground.

PerennialCalifornia nativeRated for 4 of 6 zones

How often to water California hibiscus, 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 California hibiscus 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

  • Soil drying 1 to 2 inches down around the clump means California hibiscus needs water
  • Large leaves wilting by midday and slow to recover show the root zone is too dry
  • Few or small flowers on a plant in dry soil can reflect too little water for a marsh native
  • Leaf edges scorching in hot, dry wind show the plant is losing water faster than its roots can supply

How to water it

  • Water California hibiscus deeply around the clump so the soil stays moist like a marsh edge
  • Keep the root zone damp well below the surface, refreshing it before the top inch dries
  • Plant in heavy, moisture-holding soil at a pond edge, swale or low spot
  • Mulch thickly with compost to slow drying around the rhizomes
  • Widen the moist area as the rhizomes send up more stems

Through the seasons

Keep a new California hibiscus wet through its first season, since it comes from freshwater marshes. Established clumps still need steady moisture through the warm months, when stems lengthen and flowers open. Water needs fall in the cool months, though the soil should stay damp. WUCOLS rates California hibiscus high water on the north-central coast, on the south coast and in South Inland. Its Central Valley rating is moderate water. WUCOLS has not evaluated it for the high desert or the low desert.

In pots

California hibiscus can grow in a large container if the mix stays wet, much like the marsh edges where it grows wild. Use a deep pot and a heavy, moisture-holding mix, and stand it in a saucer that you keep filled in summer. Check the water daily during heat waves, since a pot dries far faster than a marsh. In winter, keep the mix damp even when the plant looks idle.

1 Your climate zone six WUCOLS zones, each from its own reference city
2.67gal per sq ft in JulyModerate water use in the Central Valley zone
A year
17.11 gal per sq ft
Reference
Sacramento climate table
Counts
Plant need, before sprinkler losses
1.02.03.04.00.4JAN0.65FEB1.09MAR1.52APR2.08MAY2.48JUN2.67JUL2.39AUG1.8SEP1.18OCT0.56NOV0.34DEC1.02.03.04.00.4JFM1.52AMJ2.67JAS1.18OND
Gallons per square foot per month, Central Valley. Peak 2.67 in Jul, 17.11 a year.

Monthly water need by climate zone

California Hibiscus: gallons per square foot per month, by WUCOLS climate zone

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.60.41.241.24––
Feb0.840.651.291.39––
Mar1.391.091.842.08––
Apr1.881.522.232.58––
May2.332.082.583.12––
Jun2.582.482.783.67––
Jul2.582.673.174.02––
Aug2.382.392.983.72––
Sep1.981.82.382.98––
Oct1.391.181.842.13––
Nov0.740.561.341.44––
Dec0.50.341.041.09––
Year19.217.1124.829.46––

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 moderate water in the Central Valley, like California hibiscus. Plants that drink alike can share one valve and one schedule.

DahliasDahlia spp.moderate water, Central Valley2.67 gal/sq ft in JulyFernsNephrolepis cordifolia (SHADE IN DESERT)moderate water, Central Valley2.67 gal/sq ft in JulyDayliliesHemerocallis spp. & cvs.moderate water, Central Valley2.67 gal/sq ft in JulyBegoniasBegonia & ssp. & cvs. (shade in the desert)moderate water, Central Valley2.67 gal/sq ft in JulyCalla LiliesZantedeschia aethiopica SHADE IN DESERTmoderate water, Central Valley2.67 gal/sq ft in JulySageSalvia officinalis and cvs.moderate water, Central Valley2.67 gal/sq ft in JulyBicolor MonkshoodAconitum cammarummoderate water, Central Valley2.67 gal/sq ft in JulyGarden MonkshoodAconitum napellusmoderate water, Central Valley2.67 gal/sq ft in JulyCarpet BugleAjuga reptans (shade)moderate water, Central Valley2.67 gal/sq ft in JulySnowdrop WindflowerAnemone sylvestrismoderate water, Central Valley2.67 gal/sq ft in JulyMountain SandwortArenaria montanamoderate water, Central Valley2.67 gal/sq ft in JulySwamp MilkweedAsclepias incarnatamoderate water, Central Valley2.67 gal/sq ft in JulyOrange MilkweedAsclepias tuberosamoderate water, Central Valley2.67 gal/sq ft in JulyGreater MasterwortAstrantia majormoderate water, Central Valley2.67 gal/sq ft in JulyHardy BegoniaBegonia grandismoderate water, Central Valley2.67 gal/sq ft in JulyWax BegoniaBegonia semperflorensmoderate water, Central Valley2.67 gal/sq ft in July

Similar plants that need less water 16

Rated lower than California hibiscus in the Central Valley. Worth a look for a new bed or a lawn replacement.

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 California hibiscus, 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 California hibiscus in summer?

In July, established California hibiscus in loam needs a deep watering about every 5 days in the Central Valley, about every 5 days on the south coast and about every 4 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 California hibiscus need per day?

In July in the Central Valley, established California hibiscus needs about 0.3 gallons a day for a plant 2 feet across and about 1.1 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 California hibiscus change across California?

Yes. WUCOLS rates California hibiscus separately for each of the six California climate zones: high water in the North-Central Coastal zone, moderate water in the Central Valley zone, high water in the South Coastal zone, high water 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 California hibiscus really native?

Yes. It grows wild only in the Bay Delta area of the Sacramento and San Joaquin valleys, in marshes, ditches and stream edges. That wetland home is why it needs moist ground.

Can California hibiscus grow in a dry garden?

No. It comes from freshwater wetlands and wants moist ground. Plant it near a pond, in a swale or where runoff collects.

What do California hibiscus flowers look like?

They are large and showy, with white petals marked by a rose-red center. Each flower sits alone where a leaf meets the stem.

How tall does California hibiscus get?

Its many hairy stems reach about 3 to 6 feet. Give it room to spread from rhizomes, and keep the whole clump moist.

Is California hibiscus rare?

Yes. It is rare in the wild, threatened by changes to riverbanks, development and invasive plants. Buying nursery-grown plants keeps wild populations intact.

More plant watering guides

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Sources