WateringTimesWatering plan, $19
Saccharum ravennae (Erianthus ravennae), WUCOLS IV

How often to water plume grass in California

In July on the south coast, established plume grass needs about 0.6 gallons a week for a plant 2 feet across. Plume grass, also called Ravenna grass, is a big warm-season clumping grass from the Mediterranean, 6 to 8 feet tall and 4 to 6 feet wide. Tall stems carry feathery plumes in late summer that turn silvery and then red-tinged in fall, staying showy into winter. It self-sows, especially in damp spots, and its leaves have sharp edges.

Ornamental grassRated for 2 of 6 zones

How often to water plume grass, 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 plume grass 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 6 inches down beside the clump in summer means plume grass can take a deep drink
  • Leaves curling tightly during a long hot spell suggest thirst
  • Floppy, leaning stems in moist, rich soil point to too much water and fertility
  • A dead center in an old clump is normal aging, not a water problem

How to water it

  • Water deeply and infrequently, letting the soil dry between soakings
  • Plant in full sun in dry to medium, well-drained soil
  • Avoid moist, fertile spots where it flops and spreads
  • Cut it to the ground in late winter or early spring
  • Remove seed heads before they shed if seedlings appear

Through the seasons

Water new plants regularly until roots establish. Once settled, it is drought tolerant and needs only deep, occasional water, more in desert heat. It grows through the warm months, plumes in late summer and looks good into winter before the late-winter cutback. WUCOLS rates plume grass low water on the south coast. In the high desert it carries a moderate water rating. WUCOLS has not evaluated it for the north-central coast, the Central Valley, South Inland or the low desert.

In pots

Plume grass is large for a pot, but a young clump can grow in a big, heavy container, which also keeps seedlings in check. Use a lean, well-drained mix. Water when the top few inches are dry, until it drains through. In summer heat, check every few days. Keep the saucer empty. Wear gloves and cut it back to the base in late winter. In winter, water only if the mix dries out.

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

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

Monthly water need by climate zone

Plume Grass: gallons per square foot per month, by WUCOLS climate zone

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan––0.31–0.74–
Feb––0.32–0.93–
Mar––0.46–1.46–
Apr––0.56–1.89–
May––0.64–2.39–
Jun––0.69–2.85–
Jul––0.79–3.04–
Aug––0.74–2.79–
Sep––0.6–2.14–
Oct––0.46–1.46–
Nov––0.33–0.93–
Dec––0.26–0.65–
Year––6.2–21.27–

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 8

Rated not evaluated in the Central Valley, like plume grass. Plants that drink alike can share one valve and one schedule.

Clublawn GrassCorynephorus canescensnot rated, Central Valleyno Central Valley ratingBlue Hair GrassKoeleria glaucanot rated, Central Valleyno Central Valley ratingGolden Wood MilletMilium effusumnot rated, Central Valleyno Central Valley ratingCommon ReedPhragmites australisnot rated, Central Valleyno Central Valley ratingSand RyegrassLeymus arenariusnot rated, Central Valleyno Central Valley ratingGolden Meadow FoxtailAlopecurus pratensis 'Aureus'not rated, Central Valleyno Central Valley ratingTufted FescueFestuca amethystinanot rated, Central Valleyno Central Valley ratingVariegated Water GrassGlyceria maxima 'Variegata'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 plume grass, 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 water does plume grass need per day?

In July on the south coast, established plume grass needs about 0.1 gallons a day for a plant 2 feet across and about 0.3 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 plume grass change across California?

Yes. WUCOLS rates plume grass separately for each of the six California climate zones: not evaluated in the North-Central Coastal zone, not evaluated in the Central Valley zone, low water in the South Coastal zone, not evaluated in the South Inland zone, moderate water 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 plume grass invasive?

It self-sows and can be invasive, especially in damp locations. Remove seed heads if seedlings appear. Keep it away from wildlands and creeks.

When should I cut back plume grass?

Cut it to the ground in late winter or early spring. The center of the clump tends to die out otherwise. Wear gloves, since the leaves are sharp.

Why is my plume grass flopping?

It does not thrive in moist or fertile soil, where stems often need support. Water less and skip fertilizer. Full sun helps.

Are plume grass plumes good for arrangements?

Yes, the plumes are excellent fresh or dried. Cut them as they open. They hold color into winter.

Is plume grass hard to remove?

It can be aggressive and difficult to remove once established. Plant it where you want it to stay. Dig out seedlings early.

More plant watering guides

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Sources