WateringTimesWatering plan, $19
Gunnera tinctoria, WUCOLS IV

How often to water Chilean rhubarb in California

In July on the north-central coast, established Chilean rhubarb in loam needs a deep watering about every 6 days: about 1.5 gallons each time for a plant 2 feet across, about 1.8 gallons a week. Chilean rhubarb is a huge perennial from Chile that spreads into dense clumps. Its rounded, deeply lobed leaves reach 3 to 6 feet wide on stout, prickly stalks, and thick spikes of tiny red-brown flowers appear in summer. It grows poorly in dry soil and deep shade, frost can harm its crown, and it is a known invader of wet ground.

PerennialRated for 3 of 6 zones

How often to water Chilean rhubarb, 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 Chilean rhubarb 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 at the surface beside the clump in summer means Chilean rhubarb is already short of water
  • Giant leaves collapsing or folding in afternoon heat point to too little water
  • Leaf edges crisping and browning in a dry spell suggest the root zone dried out
  • A blackened crown after a freeze points to frost damage, not a water problem

How to water it

  • Keep the soil permanently damp with slow, deep watering
  • Water the whole root zone so it never dries between soakings
  • Plant in sun or light shade on wet ground away from creeks and wild wetlands
  • Cut off flower spikes before seed ripens to limit spread
  • Shelter the crown from hard frost

Through the seasons

A new plant needs wet soil from day one. Established clumps still need constant moisture all season, since growth is poor on dry ground. Leaves die back in cold winters, and the crown can be hurt by frost. Cal-IPC watches it closely because birds and water carry its seeds into wild wetlands. WUCOLS rates Chilean rhubarb high water on the north-central coast, on the south coast and in South Inland. WUCOLS marks it as not suited to the high desert or the low desert, and has not evaluated it for the Central Valley.

In pots

Chilean rhubarb is far too big for most pots, and growing it contained is wise given how it spreads. If you try, use a very large tub stood in a tray that holds water. Fill it with a heavy, moisture-holding mix. Top up whenever the surface starts to dry, which in summer can be daily. Snip flower spikes before they set seed. In winter, keep the mix damp and protect the crown from frost.

1 Your climate zone six WUCOLS zones, each from its own reference city
Not ratedWUCOLS does not rate Chilean Rhubarb for the Central Valley zone
A year
no figure
Reference
Sacramento climate table
Counts
Plant need, before sprinkler losses

WUCOLS lists Chilean Rhubarb as not evaluated for the Central Valley zone, so no monthly figure is computed here.

Monthly water need by climate zone

Chilean Rhubarb: gallons per square foot per month, by WUCOLS climate zone

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.6–1.241.24––
Feb0.84–1.291.39––
Mar1.39–1.842.08––
Apr1.88–2.232.58––
May2.33–2.583.12––
Jun2.58–2.783.67––
Jul2.58–3.174.02––
Aug2.38–2.983.72––
Sep1.98–2.382.98––
Oct1.39–1.842.13––
Nov0.74–1.341.44––
Dec0.5–1.041.09––
Year19.2–24.829.46––

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 not evaluated in the Central Valley, like Chilean rhubarb. Plants that drink alike can share one valve and one schedule.

Lilyleaf LadybellsAdenophora liliifolianot rated, Central Valleyno Central Valley ratingArnicaArnica montananot rated, Central Valleyno Central Valley ratingFrilly BergeniaBergenia ciliatanot rated, Central Valleyno Central Valley ratingCabbage on a StickBrighamia insignisnot rated, Central Valleyno Central Valley ratingBasket PlantCallisia fragransnot rated, Central Valleyno Central Valley ratingForest SedgeCarex sylvaticanot rated, Central Valleyno Central Valley ratingUmbrella DracaenaDianella ensifolianot rated, Central Valleyno Central Valley ratingRusty FoxgloveDigitalis ferrugineanot rated, Central Valleyno Central Valley ratingBig-Flowered FoxgloveDigitalis grandifloranot rated, Central Valleyno Central Valley ratingWoolly FoxgloveDigitalis lanatanot rated, Central Valleyno Central Valley ratingSunset FoxgloveDigitalis obscuranot rated, Central Valleyno Central Valley ratingMale FernDryopteris filix-masnot rated, Central Valleyno Central Valley ratingAlpine Sea HollyEryngium alpinumnot rated, Central Valleyno Central Valley ratingPurple SpurgeEuphorbia dulcisnot rated, Central Valleyno Central Valley ratingQueen of the MeadowFilipendula ulmarianot rated, Central Valleyno Central Valley ratingDropwortFilipendula vulgaris (Filipendula hexapetala)not rated, Central Valleyno Central Valley rating
Minutes for your sprinklers

Turn this into minutes on your water days

Every city page has a calculator that takes Chilean rhubarb, 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 Chilean rhubarb in summer?

In July, established Chilean rhubarb in loam needs a deep watering 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 Chilean rhubarb need per day?

In July on the north-central coast, established Chilean rhubarb needs about 0.3 gallons a day for a plant 2 feet across and about 1.0 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 Chilean rhubarb change across California?

Yes. WUCOLS rates Chilean rhubarb separately for each of the six California climate zones: high water in the North-Central Coastal zone, not evaluated in the Central Valley zone, high water in the South Coastal zone, high 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.

Is Chilean rhubarb invasive in California?

Cal-IPC lists it on its watch list, and it occurs in the central coast ranges. It spreads by seed and rhizomes, and birds and water carry the seeds. It is banned from sale in the UK.

How big does Chilean rhubarb get?

Its leaves alone can reach 3 to 6 feet across. It spreads into dense clumps. Give it lots of room or choose a smaller plant.

Can Chilean rhubarb grow in a dry garden?

No, growth is poor on dry soils. It needs permanently damp ground. It is not a fit for dry gardens.

Does Chilean rhubarb need sun?

It prefers sun or light shade. Growth is poor in deep shade. In sun, keep the soil wet at all times.

How do I stop Chilean rhubarb from spreading?

Cut flower spikes before seeds ripen. Dig out rhizomes that stray. Keep it far from creeks and wetlands.

More plant watering guides

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Sources