WateringTimesWatering plan, $19
Delphinium non-native spp., WUCOLS IV

How often to water delphinium in California

In July in the Central Valley, established delphinium 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. Delphinium is a tall perennial grown for vivid flower spikes in early summer, and the tallest garden kinds reach about 6 feet. Most plants sold are complex hybrids. It likes fertile, well-drained soil, full sun and cool summers, with afternoon shade where summers are hot. It needs steady moisture, and the plant is highly poisonous.

PerennialRated for 4 of 6 zones

How often to water delphinium, 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 delphinium 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

  • Delphinium leaves wilting in afternoon heat while the soil is dry an inch or two down mean it needs water
  • Lower leaves yellowing in soggy soil point to poor drainage
  • White powdery patches on the leaves point to powdery mildew, not thirst
  • Ragged holes in spring shoots point to slugs and snails

How to water it

  • Keep the soil damp but not soggy through the growing season
  • Plant in full sun in fertile, well-drained soil enriched with compost
  • Give it afternoon shade in hot-summer areas
  • Stake tall stems and shelter them from wind
  • Cut spent spikes back to the base leaves to encourage a second bloom

Through the seasons

Water new plants regularly through their first summer so the roots stay moist. Established plants still need extra summer water to keep the soil damp but not soggy. Main bloom comes in early summer, and cutting back can bring more flowers in late summer or fall. The plants die back in winter, and soggy winter soil can rot them. WUCOLS rates delphinium moderate water on the north-central coast, on the south coast and in South Inland. The Central Valley carries a high water rating. WUCOLS marks it as not suited to the high desert or the low desert.

In pots

Shorter delphiniums grow well in large containers. Use a fertile, well-drained mix. Water whenever the top inch dries, and never let the pot dry out completely. In summer heat, check daily and give afternoon shade. Empty the saucer so roots do not sit wet. Cut spent spikes for more flowers. In winter, move the pot into a rain shadow by a wall so it stays drier.

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

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

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.370.640.780.78––
Feb0.531.040.810.87––
Mar0.871.741.151.3––
Apr1.182.431.41.61––
May1.463.321.611.95––
Jun1.613.971.742.29––
Jul1.614.271.982.51––
Aug1.493.821.862.33––
Sep1.242.881.491.86––
Oct0.871.881.151.33––
Nov0.470.890.840.9––
Dec0.310.550.650.68––
Year1227.3815.518.41––

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 high water in the Central Valley, like delphinium. 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 JulyRushJuncus aquatic spp. (native and non-native spp.)high 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 July

Similar plants that need less water 16

Rated lower than delphinium 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 delphinium, 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 delphinium in summer?

In July, established delphinium 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 delphinium need per day?

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

Yes. WUCOLS rates delphinium separately for each of the six California climate zones: moderate 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 suited to this region in the High and Intermediate Desert zone, not suited to this region in the Low Desert zone. The monthly table above shows how the same rating translates into different gallon amounts as reference evapotranspiration changes.

Is delphinium poisonous?

Yes, delphinium is highly poisonous. Keep it away from children and pets. Wash your hands after handling it.

Do delphiniums need staking?

Tall kinds need stakes or sturdy supports. Spikes can bend or break in wind and rain. Set supports in spring before the stems grow tall.

Will delphinium bloom again?

Yes, cut spent spikes back to the base leaves after the first bloom. Many will flower again in late summer or fall. Keep watering after the cut.

Why are my delphiniums short-lived?

They are often short-lived perennials, and they struggle in hot summers. Afternoon shade and steady moisture help. Soggy winter soil also kills them.

What eats delphinium shoots?

Slugs and snails devour young growth in spring. Check new shoots after rain. Protect them early.

More plant watering guides

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Sources