WateringTimesWatering plan, $19
Iris xiphium, WUCOLS IV

How often to water Spanish iris in California

In July in the Central Valley, established Spanish iris needs about 1.9 gallons a week for a plant 2 feet across. Spanish iris is a clump-forming bulb from the western Mediterranean with narrow, lance-shaped leaves. In late spring to early summer each bulb produces two flowers, usually pale to deep blue or violet, sometimes white or yellow, with an orange or yellow mark on each fall. It grows in any free-draining soil in full sun, and the leaves die down after bloom.

BulbRated for 5 of 6 zones

How often to water Spanish iris, 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 Spanish iris and the rest of your yard, on the days your water supplier allows.Get the plan for $19

How this is worked out: the plant’s WUCOLS rating times your city’s climate for the month, over the area the plant covers. 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 between the leaves in spring signals Spanish iris needs water while growing
  • Leaves wilting before the flower buds open can indicate a dry spring
  • Leaves yellowing and dying after bloom is the normal start of summer rest
  • Bulbs rotting or failing to return in heavy, wet soil point to poor drainage

How to water it

  • Water from fall through bloom, while leaves are green, if rain falls short
  • Soak a few inches down, then let the top couple of inches dry
  • Plant bulbs in full sun in neutral or slightly alkaline, free-draining soil
  • Stop watering once the foliage dies down, and remove the dead leaves
  • Lift and divide crowded clumps in early autumn

Through the seasons

Spanish iris grows through the cool, wet months and flowers in late spring to early summer. After bloom the leaves die down, and the bulbs rest dry until fall. Water only during that growing window when rain is not enough. WUCOLS rates Spanish iris moderate water on the north-central coast and in the Central Valley. The high desert and the low desert share that moderate water rating. South Inland gives it a very low water rating. WUCOLS has not evaluated it for the south coast.

In pots

Spanish iris grows well in deep pots of gritty, free-draining mix, and pots make good cut flowers easy to reach. Water while leaves are growing whenever the top inch dries, letting it drain. Empty the saucer each time. After the leaves die down, stop watering and keep the pot dry through summer. Start watering again when new shoots appear in fall. Repot in fall.

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
0.761.52.33.00.4JAN0.65FEB1.09MAR1.52APR2.08MAY2.48JUN2.67JUL2.39AUG1.8SEP1.18OCT0.56NOV0.34DEC0.761.52.33.00.4JFM1.52AMJ2.67JAS1.18OND
Gallons per square foot per month, Central Valley. Peak 2.67 in Jul, 17.11 a year.

Monthly water need by climate zone

Spanish Iris: gallons per square foot per month, by WUCOLS climate zone

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.370.4–0.080.740.78
Feb0.530.65–0.090.930.93
Mar0.871.09–0.131.461.52
Apr1.181.52–0.161.891.95
May1.462.08–0.22.392.45
Jun1.612.48–0.232.852.79
Jul1.612.67–0.253.042.85
Aug1.492.39–0.232.792.6
Sep1.241.8–0.192.142.08
Oct0.871.18–0.131.461.49
Nov0.470.56–0.090.930.96
Dec0.310.34–0.070.650.68
Year1217.11–1.8421.2721.08

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 6

Rated moderate water in the Central Valley, like Spanish iris. Plants that drink alike can share one valve and one schedule.

CannasCanna spp.moderate water, Central Valley2.67 gal/sq ft in JulyGladiolusGladiolus hybrids & selectionsmoderate water, Central Valley2.67 gal/sq ft in JulyCreeping ButtercupRanunculus spp. (summer growing)moderate water, Central Valley2.67 gal/sq ft in JulyAlliumAllium spp.moderate water, Central Valley2.67 gal/sq ft in JulyPoppy AnemoneAnemone coronariamoderate water, Central Valley2.67 gal/sq ft in JulyPersian CyclamenCyclamen persicum and hybrids (shade)moderate water, Central Valley2.67 gal/sq ft in July

Similar plants that need less water 9

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

Star of BethlehemOrnithogalum arabicumlow water, Central Valley1.07 gal/sq ft in JulyIvy Leaf CyclamenCyclamen hederifoliumlow water, Central Valley1.07 gal/sq ft in JulySummer SnowflakeLeucojum aestivumlow water, Central Valley1.07 gal/sq ft in JulyWhite Rain LilyZephyranthes candidalow water, Central Valley1.07 gal/sq ft in JulyHyacinthHyacinthus spp.low water, Central Valley1.07 gal/sq ft in JulySea SquillDrimia maritimalow water, Central Valley1.07 gal/sq ft in JulyNaked LadyAmaryllis belladonnavery low water, Central Valley0.27 gal/sq ft in JulyDaffodilNarcissus spp.very low water, Central Valley0.27 gal/sq ft in JulyGiant ScillaScilla peruviana (Scilla hughii)very low water, Central Valley0.27 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 Spanish iris, 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 much should I water Spanish iris in summer?

In July, established Spanish iris needs about 1.9 gallons in the Central Valley and 0.2 gallons in the South Inland zone each week, for a plant 2 feet across. Water deeply and let the top of the soil dry before the next watering. Skip a watering after a soaking rain.

How much water does Spanish iris need per day?

In July in the Central Valley, established Spanish iris 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 Spanish iris change across California?

Yes. WUCOLS rates Spanish iris separately for each of the six California climate zones: moderate water in the North-Central Coastal zone, moderate water in the Central Valley zone, not evaluated in the South Coastal zone, very low 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 Spanish iris the same as Dutch iris?

Dutch iris is one of its other common names, and the two are often sold together. Both grow from bulbs and bloom in late spring. Care is the same.

Why are my Spanish iris leaves dying?

The leaves die down after flowering as the bulbs go dormant. That is normal. Remove them once they are fully brown.

Is Spanish iris poisonous?

It is harmful if eaten, including to pets. Wear gloves when handling bulbs. Keep bulbs away from children and dogs.

Can Spanish iris grow in wet soil?

No, bulb irises do not grow well in permanently wet or very heavy soil. Plant in free-draining ground. Raised beds help in clay.

When should I divide Spanish iris?

Lift and divide clumps in early autumn, before growth starts. Replant at the same depth. Water lightly until shoots appear.

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Sources