WateringTimesWatering plan, $19
Echinops exaltatus, WUCOLS IV

How often to water tall globe thistle in California

In July in the Central Valley, established tall globe thistle 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. Tall globe thistle is a big, clump-forming perennial in the daisy family, often 5 to 8 feet tall. Pale, silvery-blue balls of flowers ride on branched stems above thistle-like leaves through summer and fall. It does best in lean, well-drained soil and full sun. An established clump takes some dryness, yet it still wants deep soaks through a California summer.

PerennialRated for 3 of 6 zones

How often to water tall globe thistle, 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 tall globe thistle 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 4 inches down beside the clump while it is in bloom means it is time for a deep soak
  • Lower leaves that brown and wither early in summer, over dry soil, point to a clump short of water
  • Leaves that yellow while the soil stays wet for days show the ground is too soggy for this lean-soil plant
  • Sticky clusters of small insects on stems and flower heads are likely aphids, which watering will not fix
  • Bare, brown stems from late fall through winter are normal dieback, not drought damage

How to water it

  • Water at the base of the clump with drip or a slow hose, keeping spray off the tall flower stems
  • Soak until the soil is wet about a foot down, then let the top several inches dry before watering again
  • Plant in full sun in lean, fast-draining soil, and skip the rich amendments that keep a root zone damp
  • Use gravel or a thin bark mulch around the clump, kept clear of the crown
  • Move the drip line outward as the clump widens over its first few years

Through the seasons

Water a new clump deeply through its first summer, until its roots run well into the surrounding soil. After that, deeper and more widely spaced soaks suit it. New leaves rise in spring, and the round flower heads open through summer into fall. The top dies back in winter, when its water use is low. Winter rain covers the cool months on the coast and in the Central Valley. WUCOLS rates it moderate water on the north-central coast, in the Central Valley and on the south coast. WUCOLS has not evaluated it for South Inland, the high desert or the low desert.

In pots

Tall globe thistle grows too tall and wide for most containers. A young plant or a fresh division can spend a season in a deep pot before it goes in the ground. Use a gritty mix and a pot with open drainage holes. In summer heat, check the mix 2 inches down every couple of days. Water until it drains from the holes, then empty the saucer. Once the top dies down in late fall, water only when the mix is dry well below the surface.

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

Tall Globe Thistle: gallons per square foot per month, by WUCOLS climate zone

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.370.40.78–––
Feb0.530.650.81–––
Mar0.871.091.15–––
Apr1.181.521.4–––
May1.462.081.61–––
Jun1.612.481.74–––
Jul1.612.671.98–––
Aug1.492.391.86–––
Sep1.241.81.49–––
Oct0.871.181.15–––
Nov0.470.560.84–––
Dec0.310.340.65–––
Year1217.1115.5–––

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 tall globe thistle. 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 tall globe thistle 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 tall globe thistle, 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 tall globe thistle in summer?

In July, established tall globe thistle in loam needs a deep watering about every 5 days in the Central Valley and about every 7 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 tall globe thistle need per day?

In July in the Central Valley, established tall globe thistle 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 tall globe thistle change across California?

Yes. WUCOLS rates tall globe thistle 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, 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 tall globe thistle drought tolerant?

An established clump copes with some dryness, and British garden references list it as drought resistant. Where WUCOLS has rated it in California, it rates moderate, so it still needs deep soaks through the dry season. Treat it as a plant that likes lean soil, not as a no-water plant.

How tall does tall globe thistle get?

It usually reaches 5 to 8 feet, with a spread of 3 to 5 feet. It takes two to five years to reach full size. Plant it at the back of a border, where its height will not shade smaller plants.

Will globe thistle spread by seed?

Yes, it can self-sow. Cut off the flower heads as they fade to prevent seedlings. Leave a few only where new plants are welcome.

Can I cut globe thistle for vases?

Yes. The round, silvery-blue heads are grown as cut flowers. Cut them in the cool of the morning, after the clump has had a deep soak the day before.

How do I divide a tall globe thistle?

Divide the clump in spring or fall. Water it a day or two before you dig, and keep the divisions moist until new growth starts. Root cuttings taken in winter are another way to make new plants.

What are the bugs on my globe thistle?

They are most likely aphids, which gather on stems and buds and leave sticky honeydew. A strong stream of water knocks many off sturdy plants, and lady beetles and other natural enemies help. They are not a sign that the soil is too wet or too dry.

More plant watering guides

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Sources