WateringTimesWatering plan, $19
Aspidistra elatior (shade), WUCOLS IV

How often to water cast iron plant in California

In July in the Central Valley, established cast iron plant 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. Cast iron plant is an evergreen perennial that spreads slowly by rhizomes into upright clumps of broad, glossy, dark green leaves about 2 feet tall. It earned its name by shrugging off neglect, dry spells and dim corners. It needs shade, since direct sun burns the leaves, and it rots if the soil stays soggy.

PerennialRated for 6 of 6 zones

How often to water cast iron plant, 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 cast iron plant 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 dry 2 inches down among the clumps in summer signals that cast iron plant is ready for water
  • Leaves leaning and losing their upright stance can indicate a long dry stretch
  • Brown, bleached patches on leaves point to direct sun, not a shortage of water
  • Yellowing leaves with mushy bases at the rhizomes over wet ground suggest overwatering or poor drainage

How to water it

  • Water the soil between the leaf stems with drip or a soaker, keeping the clump base out of puddles
  • Soak 6 to 8 inches down from spring through fall, then let the upper inch or two dry
  • Plant in rich, well-drained soil in partial to full shade, out of afternoon sun
  • Spread leaf litter or shredded bark around the clumps to keep roots cool
  • Add coverage as rhizomes creep outward and new leaves fill the gaps

Through the seasons

Give a new planting steady moisture through its first summer while rhizomes spread. Established clumps tolerate dry, poor soil, yet they look best with regular water from spring to autumn. Water sparingly in winter. The plant is evergreen, so leaves stay through the year and a scorched leaf stays marked. Coastal and valley rain normally supplies the winter months. On the north-central coast and in the Central Valley, WUCOLS rates cast iron plant low water. The south coast, South Inland, the high desert and the low desert each carry a moderate water rating for it.

In pots

Cast iron plant is one of the easiest container plants for a shady porch or a dim room. Push a finger into the mix, and once the top inch or two is dry, pour water through until it runs out below. Do not let the pot sit in a full saucer. In warm months that may mean every few days outdoors and much less indoors. In winter, water sparingly and shelter the pot from cold, drying wind.

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

Cast Iron Plant: gallons per square foot per month, by WUCOLS climate zone

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.150.160.780.780.740.78
Feb0.210.260.810.870.930.93
Mar0.350.431.151.31.461.52
Apr0.470.611.41.611.891.95
May0.580.831.611.952.392.45
Jun0.640.991.742.292.852.79
Jul0.641.071.982.513.042.85
Aug0.60.951.862.332.792.6
Sep0.50.721.491.862.142.08
Oct0.350.471.151.331.461.49
Nov0.190.220.840.90.930.96
Dec0.120.140.650.680.650.68
Year4.86.8415.518.4121.2721.08

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 cast iron plant. 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 cast iron plant, 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 cast iron plant in summer?

In July, established cast iron plant in loam needs a deep watering about every 14 days in the Central Valley, about every 7 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 cast iron plant need per day?

In July in the Central Valley, established cast iron plant 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 cast iron plant change across California?

Yes. WUCOLS rates cast iron plant separately for each of the six California climate zones: low water in the North-Central Coastal zone, low water in the Central Valley zone, moderate 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.

Can cast iron plant grow in deep shade?

Yes, it is one of the best plants for dense shade. It does not tolerate direct sun, which bleaches and burns the leaves. Shade also slows drying, so check the soil before watering.

Why are my cast iron plant leaves turning brown?

Bleached or brown patches usually mean too much sun. Brown, mushy bases point to wet soil instead. Move it into shade or improve drainage, depending on which you see.

Is cast iron plant deer resistant?

Yes, it resists deer damage and has no serious pest problems. It is also slightly salt tolerant. Watch drainage more than pests.

Can cast iron plant grow indoors?

Yes, it is a classic houseplant for low light. Indoors the mix dries slowly, so water only when the top inch is dry. Wipe dust off the broad leaves now and then.

Are there variegated cast iron plants?

Yes, many selections carry white or yellow stripes, spots or speckles. Their watering is the same as the green form.

More plant watering guides

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Sources