WateringTimesWatering plan, $19
Carex flacca (Carex glauca), WUCOLS IV

How often to water blue sedge in California

In July in the Central Valley, established blue sedge in loam needs a deep watering about every 5 days: about 1.5 gallons each time for a plant 2 feet across, about 1.9 gallons a week. Blue sedge is a low evergreen sedge from southern Europe and North Africa, 6 to 10 inches tall, with narrow silvery blue leaves. It spreads by rhizomes into a soft groundcover 2 to 3 feet wide, slowly with little water and much faster with more. It grows in sun or light shade in almost any soil and even accepts periodic flooding.

PerennialRated for 3 of 6 zones

How often to water blue sedge, 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 blue sedge 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 around the clumps in summer heat means it is time to water, especially in full sun
  • Runners racing beyond the bed edge point to generous water and fertilizer, which speed its spread
  • Tired, flattened foliage calls for a trim to about 4 inches, which keeps the planting vigorous, rather than extra water
  • Thin, stressed patches in hot afternoon sun point to a site that needs some afternoon shade

How to water it

  • Water evenly over the planting with drip or a low sprinkler, wetting the top 6 inches
  • Let the top inch or two dry between waterings, and give less water where you want slower spread
  • Plant in cool sun or light shade, with afternoon shade in hot inland gardens, in almost any soil
  • Mow or trim at about 4 inches a few times a year to keep it neat and vigorous
  • Edge the planting to contain the runners

Through the seasons

Water new plantings regularly until they root in. This cool-season evergreen keeps its blue color all year, and inconspicuous flower stems appear in early summer. In full sun it needs average to occasional water through summer, while part shade lets it get by on less. Winter rain usually covers it on the coast and in the Central Valley. WUCOLS rates blue sedge moderate water on the north-central coast and in the Central Valley, and low water on the south coast. WUCOLS has not evaluated it for South Inland, the high desert or the low desert.

In pots

Blue sedge grows well in containers, and it can even sit in a water garden with its pot up to 2 inches below the surface. In an ordinary pot, use a moisture-holding mix and a container with drainage holes. During summer heat, feel the mix every other day and water when the top inch has dried. Let excess drain, then empty the saucer. Trim tired leaves in spring, and in winter water only when the mix dries.

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
0.671.32.02.70.4JAN0.65FEB1.09MAR1.52APR2.08MAY2.48JUN2.67JUL2.39AUG1.8SEP1.18OCT0.56NOV0.34DEC0.671.32.02.70.4JFM1.52AMJ2.67JAS1.18OND
Gallons per square foot per month, Central Valley. Peak 2.67 in Jul, 17.11 a year.

Monthly water need by climate zone

Blue Sedge: gallons per square foot per month, by WUCOLS climate zone

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.370.40.31–––
Feb0.530.650.32–––
Mar0.871.090.46–––
Apr1.181.520.56–––
May1.462.080.64–––
Jun1.612.480.69–––
Jul1.612.670.79–––
Aug1.492.390.74–––
Sep1.241.80.6–––
Oct0.871.180.46–––
Nov0.470.560.33–––
Dec0.310.340.26–––
Year1217.116.2–––

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 moderate water in the Central Valley, like blue sedge. Plants that drink alike can share one valve and one schedule.

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

Similar plants that need less water 16

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

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 blue sedge, 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 blue sedge in summer?

In July, established blue sedge in loam needs a deep watering about every 5 days in the Central Valley and about every 18 days on the south coast. 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 blue sedge need per day?

In July in the Central Valley, established blue sedge 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 blue sedge change across California?

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

It spreads steadily by rhizomes, and it has naturalized in wildlands in parts of the northeastern United States and Canada. In California's dry summers it has rarely reseeded, and not outside irrigated areas. Keep water and fertilizer modest to slow its spread.

Can blue sedge replace a lawn?

It makes a soft, low groundcover that takes some foot traffic. Mowing at about 4 inches a few times a year keeps it neat. It will not take the heavy wear a lawn does.

Can blue sedge grow in water?

Yes. It accepts periodic flooding, and it can be planted in a water garden up to 2 inches below the surface. It also grows in ordinary garden soil.

Is Carex glauca the same as blue sedge?

Yes. The plant long sold as Carex glauca is correctly named Carex flacca. Both names still appear on nursery labels.

Why is my blue sedge spreading so fast?

Ample water and fertilizer make it spread much faster than it does in a lean, dry bed. Cut back on both, and edge the planting where you want it to stop.

More plant watering guides

Oriental PoppyEmpress TreeMartha Washington PelargoniumMoss PinkChinese PhotiniaNorway SpruceAlberta SpruceColorado Spruce

Sources