WateringTimesWatering plan, $19
Buddleja davidii and hybrids, WUCOLS IV

How often to water butterfly bush in California

In July in the Central Valley, established butterfly bush 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. Butterfly bush grows quickly into a loose shrub with long flower spikes on new wood. Its soft leaves flag in heat, but drooping alone does not establish thirst. Keep the root zone moist during growth and bloom, allowing the surface to dry between deep soakings.

ShrubRated for 6 of 6 zones

How often to water butterfly bush, 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 butterfly bush 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 2 to 3 inches down under the outer branches signals that an established butterfly bush needs water
  • Soft shoot-tip leaves still limp in the morning over dry soil can indicate thirst
  • Flower spikes that brown early can accompany dry soil during bloom, so check beneath the branches
  • Lower leaves yellowing and falling over soggy ground can indicate drainage trouble
  • Blackened, wilting shoot bases after wet weather warrant a check for water collecting around the crown

How to water it

  • Water a wide ring beneath the outer branches while keeping the woody crown clear
  • Soak about a foot deep around an established shrub, then let the soil surface dry
  • Use drip emitters or a slow hose at soil level to keep the flower spikes dry
  • Mulch beneath butterfly bush, leave its woody crown clear, and use a raised mound where water collects
  • Move emitters outward as new growth widens the shrub after its late-winter cutback

Through the seasons

Keep a new butterfly bush root ball evenly moist through its first summer while roots spread. Established shrubs can take deeper, less frequent soakings. Water matters most from late spring through early fall, when new wood grows and carries flower spikes. Reduce irrigation as growth slows and leaves fall. Winter rain can supply dormant shrubs on the coast and in the Central Valley; check desert soil through long dry spells. WUCOLS rates butterfly bush moderate water in all six climate zones.

In pots

Dwarf butterfly bushes are the ones that suit containers, and they dry out fast in California heat. Once the plant is in leaf and blooming, check the top couple of inches of mix every few days. Water until it runs from the drainage holes. Tip out any saucer that holds standing water, because the roots rot quickly in a pot that never drains. After the leaves drop the plant is dormant and needs far less: keep the mix barely damp through winter, and move the pot out of the path of roof runoff.

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
0.761.52.33.00.4JAN0.65FEB1.09MAR1.52APR2.08MAY2.48JUN2.67JUL2.39AUG1.8SEP1.18OCT0.56NOV0.34DEC0.761.52.33.00.4JFM1.52AMJ2.67JAS1.18OND
Gallons per square foot per month, Central Valley. Peak 2.67 in Jul, 17.11 a year.

Monthly water need by climate zone

Butterfly Bush: gallons per square foot per month, by WUCOLS climate zone

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.370.40.780.780.740.78
Feb0.530.650.810.870.930.93
Mar0.871.091.151.31.461.52
Apr1.181.521.41.611.891.95
May1.462.081.611.952.392.45
Jun1.612.481.742.292.852.79
Jul1.612.671.982.513.042.85
Aug1.492.391.862.332.792.6
Sep1.241.81.491.862.142.08
Oct0.871.181.151.331.461.49
Nov0.470.560.840.90.930.96
Dec0.310.340.650.680.650.68
Year1217.1115.518.4121.2721.08

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 moderate water in the Central Valley, like butterfly bush. 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 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 JulyJapanese AucubaAucuba japonica (SHADE)moderate water, Central Valley2.67 gal/sq ft in July

Similar plants that need less water 16

Rated lower than butterfly bush 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 butterfly bush, 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 butterfly bush in summer?

In July, established butterfly bush in loam needs a deep watering about every 8 days in the Central Valley, about every 11 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 butterfly bush need per day?

In July in the Central Valley, established butterfly bush 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 butterfly bush change across California?

Yes. WUCOLS rates butterfly bush separately for each of the six California climate zones: moderate water 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, moderate water 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.

How do I water a newly planted butterfly bush?

Check the nursery root ball separately from the soil around it. That small area can dry while nearby ground still feels damp. Direct water over it at first and expand the ring as the shrub establishes.

How long should I run drip on butterfly bush?

Run drip until soil is moist about a foot down across the butterfly bush's established root area. Winter pruning does not shrink that root system.

Do dwarf butterfly bushes need less water?

Their smaller spread means a smaller area to soak. Match emitter coverage to the branches rather than reducing the depth of each soaking. A dwarf still needs soil checks during growth and flowering.

Why is my butterfly bush wilting?

Compare afternoon drooping with the foliage in the cool morning. If the leaves recover, heat alone may explain the change. Persistent wilt over wet soil calls for a drainage check before more irrigation.

Why is my butterfly bush not blooming?

Flower spikes grow on new wood. A late-winter cutback and steady moisture during new growth support bloom. Remove spent spikes as they fade to encourage another round.

More plant watering guides

Greater MasterwortJapanese AucubaBrazilian Butterfly TreeHardy BegoniaWax BegoniaEnglish DaisyHyacinth OrchidJapanese Boxwood

Sources