WateringTimesWatering plan, $19
Ruta graveolens, WUCOLS IV

How often to water rue in California

In July in the Central Valley, established rue in loam needs a deep watering about every 8 days: about 8.8 gallons each time for a plant 4 feet across, about 7.6 gallons a week. Rue is a short-lived, shrubby herb with bluish gray-green foliage divided into lobed leaflets and small summer flowers. It handles dry, rocky soil well once established and self-sows to renew the planting over the years. Its sap can irritate skin in sunlight, so handle the foliage with care while watering or pruning nearby.

ShrubRated for 4 of 6 zones

How often to water rue, month by month

Your city
Plant width
4 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 rue 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 1.5 feet 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 several inches down around an established rue plant signals it needs a soak
  • Dull rue foliage in hot weather warrants checking the soil instead of judging moisture by its blue-green color
  • Dark, soft stems at a rue crown need inspection, especially where the ground remains wet
  • An older rue plant can decline with age, but inspect a sparse plant before deciding it has reached the end of its life
  • Volunteer seedlings appearing nearby show normal self-sowing, not a sign the parent plant is struggling

How to water it

  • Soak the root zone of rue with drip or a slow hose rather than wetting the foliage
  • Let the top few inches of soil dry before watering an established plant again
  • Use fast-draining, rocky or sandy soil, since standing water encourages root rot
  • Wear gloves and long sleeves when watering near or trimming the foliage in bright sun
  • Cut plants back to older wood in early spring to renew growth rather than relying on extra water

Through the seasons

Give newly planted rue regular moisture through its first summer while roots settle into the ground. Mature rue tolerates drought, but most of its evaluated California regions carry moderate water ratings. It stays evergreen in mild winters; short-lived older plants can be replaced by self-sown seedlings. WUCOLS rates it moderate water on the north-central coast, in the Central Valley and in South Inland. It rates low water on the south coast. WUCOLS has not evaluated it for the high desert or the low desert. Coastal and valley winter rain can cover part of the cool season for this plant.

In pots

Rue grows well in a container with gritty, fast-draining mix and a pot with room for its root ball. Check the top two inches often during California summer heat and water when that layer is dry. Let water run through the drainage holes, then empty the saucer so roots do not sit wet. Handle potted rue with gloves, since brushing bare skin against the foliage in sunlight can cause irritation. In winter, water only when the mix has dried, since growth and water use slow considerably.

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

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

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.370.40.310.78––
Feb0.530.650.320.87––
Mar0.871.090.461.3––
Apr1.181.520.561.61––
May1.462.080.641.95––
Jun1.612.480.692.29––
Jul1.612.670.792.51––
Aug1.492.390.742.33––
Sep1.241.80.61.86––
Oct0.871.180.461.33––
Nov0.470.560.330.9––
Dec0.310.340.260.68––
Year1217.116.218.41––

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 rue. Plants that drink alike can share one valve and one schedule.

RosesRosa hybrids..bushmoderate water, Central Valley2.67 gal/sq ft in JulyAzaleasRhododendron spp. (CA native and non-native spp.)moderate water, Central Valley2.67 gal/sq ft in JulyCamelliasCamellia japonica (SHADE IN DESERT)moderate water, Central Valley2.67 gal/sq ft in JulyGardeniasGardenia spp. & cvs.moderate water, Central Valley2.67 gal/sq ft in JulyBird of ParadiseStrelitzia reginae (shade in desert)moderate water, Central Valley2.67 gal/sq ft in JulyHibiscusHibiscus rosa-sinensismoderate water, Central Valley2.67 gal/sq ft in JulySago PalmCycas revolutamoderate water, Central Valley2.67 gal/sq ft in JulyStar JasmineTrachelospermum jasminoides and cvs.moderate water, Central Valley2.67 gal/sq ft in JulyArborvitaeThuja occidentalis ssp. & cvs.moderate water, Central Valley2.67 gal/sq ft in JulyBambooBambusa spp.moderate water, Central Valley2.67 gal/sq ft in JulyLilacsSyringa hybrids (including Descanso hybrids)moderate water, Central Valley2.67 gal/sq ft in JulySpireaSpiraea spp. (CA native and non native spp.)moderate water, Central Valley2.67 gal/sq ft in JulyButterfly BushBuddleja davidii and hybridsmoderate water, Central Valley2.67 gal/sq ft in JulySageSalvia officinalis and cvs.moderate water, Central Valley2.67 gal/sq ft in JulyRed BuckeyeAesculus paviamoderate water, Central Valley2.67 gal/sq ft in JulyWestern ServiceberryAmelanchier alnifoliamoderate water, Central Valley2.67 gal/sq ft in July

Similar plants that need less water 16

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

LavenderLavandula spp. & cvs.low water, Central Valley1.07 gal/sq ft in JulyRosemaryRosmarinus officinalislow water, Central Valley1.07 gal/sq ft in JulyBougainvilleaBougainvillea & spp. & cvs.low water, Central Valley1.07 gal/sq ft in JulyOlive TreesOlea europaea ssp. & cvs.low water, Central Valley1.07 gal/sq ft in JulyCrape MyrtleLagerstroemia spp., hybrids & cvs.low water, Central Valley1.07 gal/sq ft in JulyLantanaLantana camara ssp. & cvs.low water, Central Valley1.07 gal/sq ft in JulySalviaSalvia greggii ssp., cvs. & hybridslow water, Central Valley1.07 gal/sq ft in JulyAloeAloe spp. & cvs.low water, Central Valley1.07 gal/sq ft in JulySucculentsEcheveria spp. & cvs.low water, Central Valley1.07 gal/sq ft in JulyJunipersJuniperus spp. & cvs.low water, Central Valley1.07 gal/sq ft in JulyRussian SagePerovskia spp. & cvs.low water, Central Valley1.07 gal/sq ft in JulySagebrushArtemisia spp. (shrubby)low water, Central Valley1.07 gal/sq ft in JulyWild PrivetLigustrum vulgarelow water, Central Valley1.07 gal/sq ft in JulyCoralberrySymphoricarpos orbiculatus (SHADE)low water, Central Valley1.07 gal/sq ft in JulySydney Golden WattleAcacia longifolialow water, Central Valley1.07 gal/sq ft in JulyBlue Leaf WattleAcacia salignalow 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 rue, 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 rue in summer?

In July, established rue in loam needs a deep watering about every 8 days in the Central Valley, about every 27 days on the south coast and about every 9 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 rue need per day?

In July in the Central Valley, established rue needs about 1.1 gallons a day for a plant 4 feet across and about 4.3 gallons a day for a plant 8 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 rue change across California?

Yes. WUCOLS rates rue 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, 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 it safe to touch rue while watering nearby plants?

Brushing bare skin against rue in sunlight can cause irritation similar to a sunburn or rash. Wear gloves and long sleeves when working close to it. Water around the plant rather than handling its foliage directly.

Why does rue keep reseeding in my garden?

Rue produces volunteer seedlings when its seed is allowed to ripen and fall. Remove spent flower clusters if fewer seedlings are wanted. Check each retained seedling's soil while it establishes instead of assigning it the parent plant's watering routine.

How long does a rue plant typically live?

Rue is short-lived, commonly lasting about five years. It can replace itself through self-sowing if seedlings are allowed to grow. Check a declining plant for drainage problems as well as age instead of assuming extra water will restore it.

Can rue grow in part shade instead of full sun?

Rue accepts both full sun and partial shade. Use a draining site in either exposure, and check the soil before watering. Shade tolerance does not mean its roots should remain saturated.

Why are the stems at the base of my rue turning black?

Rue can develop root rot in poorly drained soil, so persistent wetness deserves attention. Dark stem bases alone do not establish that diagnosis. Inspect the crown and improve drainage if water is collecting there.

More plant watering guides

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Sources