WateringTimesWatering plan, $19
Juncus aquatic spp. (native and non-native spp.), WUCOLS IV

How often to water rush in California

In July in the Central Valley, established rush in loam needs a deep watering about every 3 days: about 1.5 gallons each time for a plant 2 feet across, about 3.0 gallons a week. Rushes are grass-like plants with round, upright stems that form clumps or slowly spreading colonies. This WUCOLS group covers the aquatic kinds used at pond edges and in wet ground. Many are evergreen and hold small brown flower clusters below the stem tips. Some native rushes handle everything from fairly dry soil to shallow standing water.

PerennialCalifornia nativeRated for 5 of 6 zones

How often to water rush, 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 rush 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 out at the surface around the clump in summer means rush needs water
  • Stem tips browning and the clump thinning in a dry spell point to too little moisture
  • Old stems browning in the center of a clump is normal aging
  • Stems flopping and the clump looking unruly can be fixed with a hard spring cutback

How to water it

  • Keep the soil moist to wet, especially in the warm months
  • Plant at pond edges, in rain gardens or in wet swales
  • Grow it in sun or part shade
  • Cut clumps back hard in spring to renew them
  • Use it in containers set in shallow water if you like

Through the seasons

Water new plantings often to keep the soil wet while roots establish. Established rushes want steady moisture, highest in the inland valleys, and they should never dry out in summer. Many are evergreen, and a hard cutback in spring refreshes worn clumps. WUCOLS rates rush high water on the north-central coast and in the Central Valley. On the south coast, in South Inland and in the low desert it carries a moderate water rating. WUCOLS has not evaluated it for the high desert.

In pots

Rushes grow well in containers and even in pots set at the edge of a pond, where they add tall green lines. Use a heavy, moisture-holding mix. Keep it moist, watering as soon as the surface starts to dry, which in summer can be daily. A deep saucer kept filled helps a pot that sits in full sun. Cut back tired stems in spring. In winter, keep the mix damp.

1 Your climate zone six WUCOLS zones, each from its own reference city
4.27gal per sq ft in JulyHigh water use in the Central Valley zone
A year
27.38 gal per sq ft
Reference
Sacramento climate table
Counts
Plant need, before sprinkler losses
1.12.13.24.30.64JAN1.04FEB1.74MAR2.43APR3.32MAY3.97JUN4.27JUL3.82AUG2.88SEP1.88OCT0.89NOV0.55DEC1.12.13.24.30.64JFM2.43AMJ4.27JAS1.88OND
Gallons per square foot per month, Central Valley. Peak 4.27 in Jul, 27.38 a year.

Monthly water need by climate zone

Rush: gallons per square foot per month, by WUCOLS climate zone

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.60.640.780.78–0.78
Feb0.841.040.810.87–0.93
Mar1.391.741.151.3–1.52
Apr1.882.431.41.61–1.95
May2.333.321.611.95–2.45
Jun2.583.971.742.29–2.79
Jul2.584.271.982.51–2.85
Aug2.383.821.862.33–2.6
Sep1.982.881.491.86–2.08
Oct1.391.881.151.33–1.49
Nov0.740.890.840.9–0.96
Dec0.50.550.650.68–0.68
Year19.227.3815.518.41–21.08

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 high water in the Central Valley, like rush. Plants that drink alike can share one valve and one schedule.

Japanese Sweet FlagAcorus gramineushigh water, Central Valley4.27 gal/sq ft in JulyRed GingerAlpinia purpuratahigh water, Central Valley4.27 gal/sq ft in JulyShell GingerAlpinia zerumbethigh water, Central Valley4.27 gal/sq ft in JulySiberian BuglossBrunnera macrophyllahigh water, Central Valley4.27 gal/sq ft in JulyMarsh MarigoldCaltha palustrishigh water, Central Valley4.27 gal/sq ft in JulyUmbrella Sedge and PapyrusCyperus spp. (CA native and non-native species)high water, Central Valley4.27 gal/sq ft in JulyUmbrella PlantDarmera peltata (Peltiphyllum)high water, Central Valley4.27 gal/sq ft in JulyFoxgloveDigitalis purpurea cvshigh water, Central Valley4.27 gal/sq ft in JulyLeopard PlantFarfugium japonicum cvs. (Ligularia tussilaginea cvs.)high water, Central Valley4.27 gal/sq ft in JulyTransvaal DaisyGerbera jamesonii & hybridshigh water, Central Valley4.27 gal/sq ft in JulyGiant GunneraGunnera manicatahigh water, Central Valley4.27 gal/sq ft in JulyWhite Ginger LilyHedychium coronariumhigh water, Central Valley4.27 gal/sq ft in JulyJapanese IrisIris ensatahigh water, Central Valley4.27 gal/sq ft in JulyCardinal FlowerLobelia cardinalis hybrids and cvs. (CA native and non-native spp.)high water, Central Valley4.27 gal/sq ft in JulyBananaMusa spp. (shade in low desert)high water, Central Valley4.27 gal/sq ft in JulySensitive FernOnoclea sensibilishigh water, Central Valley4.27 gal/sq ft in July

Similar plants that need less water 16

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

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
Minutes for your sprinklers

Turn this into minutes on your water days

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

In July, established rush in loam needs a deep watering about every 3 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 rush need per day?

In July in the Central Valley, established rush needs about 0.4 gallons a day for a plant 2 feet across and about 1.7 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 rush change across California?

Yes. WUCOLS rates rush separately for each of the six California climate zones: high water in the North-Central Coastal zone, high water in the Central Valley zone, moderate water in the South Coastal zone, moderate water in the South Inland zone, not evaluated 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 rushes grow in a pond?

Many aquatic rushes grow at pond edges and some in shallow water. California gray rush, for example, grows from dry shade to a few inches deep in a pond. Check the kind you buy.

Are rushes native to California?

This WUCOLS group includes both native and non-native rushes. Natives such as soft rush and California gray rush are available. Ask which kind you are buying.

How do I renew an old rush clump?

Cut it back hard in spring. Keep the soil wet as it regrows. Divide very large clumps.

Do rushes need full sun?

They grow in sun or part shade. Shade slows drying. Pick a spot that stays moist.

Are rushes the same as grasses?

No, rushes have round stems and belong to a different family. They look grassy. Their care leans wetter than most grasses.

More plant watering guides

Lacecap HydrangeaJapanese IrisBrazilian Plume FlowerCardinal FlowerBananaSensitive FernRoyal FernRedwood Sorrel

Sources