WateringTimesWatering plan, $19
Juncus acutus, WUCOLS IV

How often to water spiny rush in California

In July in the Central Valley, established spiny rush 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. Spiny rush is a California native that grows in dense clumps of rigid, cylindrical green stems, each ending in a sharp, stiff point. Clumps reach 3 feet or more, with glossy brown seed capsules in summer. In the wild it lines brackish marsh edges, streams and drainages, so a damp, low spot in the garden suits it.

PerennialCalifornia nativeRated for 3 of 6 zones

How often to water spiny 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 spiny 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 dry 3 inches down in the middle of the clump during summer signals that spiny rush needs water
  • Stem tips browning and the whole clump turning dull and straw colored can indicate a long dry spell
  • New shoots failing to appear from the base in late spring can follow a dried-out root zone
  • Stagnant water sitting around the clump for days, breeding mosquitoes, means irrigation is running longer than needed

How to water it

  • Water around the base of the clump with drip or a bubbler, keeping hands clear of the sharp tips
  • Soak the root zone deeply and recheck once the top few inches begin to dry
  • Group it with other moisture lovers at the low point of a swale or rain garden
  • Choose a low, moist spot, since it grows wild along drainages and brackish marsh edges
  • Widen the watered area as the clump thickens and new stems rise around its edge

Through the seasons

Keep a new spiny rush moist through its first summer while roots spread into the surrounding soil. Established clumps take deeper soaks with drier gaps, though they never want bone dry ground. Flowering and fruiting run into summer, when its seed capsules ripen. Winter rain covers the cool months on the coast and in the Central Valley. WUCOLS rates spiny rush moderate water in the Central Valley, on the south coast and in South Inland. WUCOLS has not evaluated it for the north-central coast, the high desert or the low desert.

In pots

Spiny rush can live in a large, heavy pot, though its sharp tips make it a poor choice beside a seat or path. Check the mix 2 inches down and water when it starts to dry, which may be every few days in hot inland weather. Water until it drains, then empty the saucer. In winter, let rain carry most of the load. Repot or divide when stems crowd the rim.

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

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

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan–0.40.780.78––
Feb–0.650.810.87––
Mar–1.091.151.3––
Apr–1.521.41.61––
May–2.081.611.95––
Jun–2.481.742.29––
Jul–2.671.982.51––
Aug–2.391.862.33––
Sep–1.81.491.86––
Oct–1.181.151.33––
Nov–0.560.840.9––
Dec–0.340.650.68––
Year–17.1115.518.41––

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 spiny rush. 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 spiny rush 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 spiny 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 spiny rush in summer?

In July, established spiny rush in loam needs a deep watering about every 5 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 spiny rush need per day?

In July in the Central Valley, established spiny rush 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 spiny rush change across California?

Yes. WUCOLS rates spiny rush separately for each of the six California climate zones: not evaluated in the North-Central Coastal zone, moderate 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, 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 spiny rush dangerous to touch?

Yes, the rigid stems end in sharp, stiff points that can jab skin and eyes. Plant it away from paths, play areas and seating. Wear gloves and eye protection when you divide or trim it.

Can spiny rush grow in salty soil?

It grows naturally along brackish marsh borders and salt marsh edges near the coast. Salty coastal ground is part of its home range. Keep it watered while it settles in.

Is spiny rush native to California?

Yes, the native form grows along the coast, in places such as Upper Newport Bay. It is uncommon overall and sits on a California Native Plant Society watch list. Buy plants from a nursery rather than digging them from the wild.

Can spiny rush go in a rain garden?

Yes, it fits the low, wet center of a rain garden or swale. It grows wild along small streams and drainages. Make sure water drains away within a few days after storms.

What were spiny rush stems used for?

Native Americans used the stems in basket making. The stems are stiff and long, which suits weaving. Harvest only from garden plants you own.

More plant watering guides

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Sources