WateringTimesWatering plan, $19
Glaucium flavum, WUCOLS IV

How often to water yellow horned poppy in California

In July in the Central Valley, established yellow horned poppy in loam needs a deep watering about every 14 days: about 1.5 gallons each time for a plant 2 feet across, about 0.8 gallons a week. Yellow horned poppy is a short-lived perennial with a low rosette of fuzzy, silvery gray-green leaves. The leaves are deeply cut and wavy at the edges. From spring into midsummer, silky golden flowers open on branched stems, followed by long, curved, horn-like seedpods. A seaside plant of lean, salty soils, it needs little water and rots in wet, heavy ground.

PerennialRated for 4 of 6 zones

How often to water yellow horned poppy, 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 yellow horned poppy 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 around a young plant in its first summer signals that it can use a soak
  • Gray leaves wilting flat during a long summer drought point to an established plant running dry
  • A rosette collapsing and rotting at the base after a wet winter in clay points to soggy soil
  • Seedlings springing up around the parent are normal, since the plant reseeds to carry on
  • An old plant fading after two or three years reflects its natural short life, not a watering failure

How to water it

  • Water at the base of the rosette, keeping the fuzzy leaves dry
  • Soak the soil about a foot down, then let it dry deeply before watering again
  • Plant in full sun in sandy or gravelly soil that drains quickly, or on a mound above heavy clay
  • Use gravel or bare soil around the crown instead of organic mulch so the base stays dry in winter
  • Keep the watered area tight and pull seedlings that stray, especially near beaches and wild land

Through the seasons

A new yellow horned poppy needs occasional soaks in its first summer while its roots settle, and then little more. It flowers from early spring into midsummer, and the pods ripen and scatter seed in late summer. Soggy winter soil, especially in clay, can rot the crown. Rain usually covers the cool months on the coast and in the Central Valley, so skip irrigation then. WUCOLS rates yellow horned poppy very low water on the south coast. It rates low water on the north-central coast, in the Central Valley and in South Inland. WUCOLS has not evaluated it for the high desert or the low desert.

In pots

Yellow horned poppy grows well in a pot of sandy, fast-draining mix, which keeps winter wet off its crown. Water when the mix is dry 2 inches down, which may take several days in mild weather. Let the excess run out freely and leave no water in the saucer. Set the pot in full sun. In a rainy winter, move it under an eave so the mix does not stay soggy. Snip seedpods before they split if you do not want seedlings.

1 Your climate zone six WUCOLS zones, each from its own reference city
1.07gal per sq ft in JulyLow water use in the Central Valley zone
A year
6.84 gal per sq ft
Reference
Sacramento climate table
Counts
Plant need, before sprinkler losses
0.270.540.801.10.16JAN0.26FEB0.43MAR0.61APR0.83MAY0.99JUN1.07JUL0.95AUG0.72SEP0.47OCT0.22NOV0.14DEC0.270.540.801.10.16JFM0.61AMJ1.07JAS0.47OND
Gallons per square foot per month, Central Valley. Peak 1.07 in Jul, 6.84 a year.

Monthly water need by climate zone

Yellow Horned Poppy: gallons per square foot per month, by WUCOLS climate zone

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.150.160.080.31––
Feb0.210.260.080.35––
Mar0.350.430.110.52––
Apr0.470.610.140.64––
May0.580.830.160.78––
Jun0.640.990.170.92––
Jul0.641.070.21––
Aug0.60.950.190.93––
Sep0.50.720.150.74––
Oct0.350.470.110.53––
Nov0.190.220.080.36––
Dec0.120.140.070.27––
Year4.86.841.557.37––

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 low water in the Central Valley, like yellow horned poppy. Plants that drink alike can share one valve and one schedule.

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 yellow horned poppy, 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 yellow horned poppy in summer?

In July, established yellow horned poppy in loam needs a deep watering about every 14 days in the Central Valley, about once a month or less on the south coast and about every 14 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 yellow horned poppy need per day?

In July in the Central Valley, established yellow horned poppy needs about 0.1 gallons a day for a plant 2 feet across and about 0.4 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 yellow horned poppy change across California?

Yes. WUCOLS rates yellow horned poppy separately for each of the six California climate zones: low water in the North-Central Coastal zone, low water in the Central Valley zone, very low water in the South Coastal zone, low 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 yellow horned poppy poisonous?

Yes. Its yellow sap contains an alkaloid, and all parts are poisonous if eaten, especially the roots. Keep it away from children and pets that chew plants.

Why did my horned poppy die after a few years?

It is short-lived and often lasts only two or three years. Reseeding keeps it going in the garden. Wet winter soil in clay can end it sooner.

Can yellow horned poppy grow at the beach?

Yes, it is a natural seaside plant of lean, salty soils and does well in coastal gardens. It can also escape into sandy wild areas, so avoid planting it next to dunes or wildlands.

When does yellow horned poppy bloom?

Mature plants flower from early spring through midsummer. Each golden flower drops its petals quickly as the horn-shaped pod grows. Plants raised from seed often bloom in their first year.

Can I use horned poppy seedpods in arrangements?

Yes. The long, horn-shaped capsules are used in dried arrangements. Cutting them before they split also stops the plant from reseeding.

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Sources