WateringTimesWatering plan, $19
Hedychium gardnerianum, WUCOLS IV

How often to water Kahili ginger in California

In July on the north-central coast, established Kahili ginger in loam needs a deep watering about every 9 days: about 1.5 gallons each time for a plant 2 feet across, about 1.1 gallons a week. Kahili ginger is a tall ginger from the region between Nepal and Indochina, growing from thick rhizomes. Its stems reach 5 to 8 feet, with broad gray-green leaves that are powdery white beneath. In late summer and early fall, spikes of fragrant lemon-yellow flowers with long red stamens open at the stem tips. It wants regular water and humus-rich soil through the warm months.

PerennialRated for 3 of 6 zones

How often to water Kahili ginger, 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 Kahili ginger 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 2 inches down under the mulch around the clump, during summer growth, means it needs water
  • Leaves that droop or roll in afternoon heat and stay limp by evening, over dry soil, point to a thirsty clump
  • Crisp brown leaf edges on a plant in a hot, sunny spot point to soil drying out too fast for that exposure
  • Yellowing, collapsing stems while the soil stays waterlogged point to poor drainage around the rhizomes
  • Leaves blackened after a frost are normal winter damage, since the foliage freezes back in cold weather, and do not mean it is dry

How to water it

  • Water around the base of the clump with drip or a soaker hose, covering the soil over the spreading rhizomes
  • Soak until water reaches about a foot down, then water again once the top 2 inches have dried
  • Spread a deep mulch of compost or shredded bark over the rhizomes to hold soil moisture
  • Plant in humus-rich soil that holds moisture but drains, in light shade or part sun
  • Extend the watered area as the rhizomes widen the clump

Through the seasons

Water a new planting steadily through its first summer while the rhizomes settle. New stems grow through spring and summer, and flowers open in late summer and early fall, so keep the soil moist through that whole stretch. At the end of the season, cut back the old flower spikes and spent foliage. In mild coastal gardens the leaves can stay green through winter, but a freeze knocks them down to the rhizomes. Winter rain covers the cool months along the coast. WUCOLS rates Kahili ginger moderate water on the north-central coast. It rates high water on the south coast and in South Inland. WUCOLS marks it as not suited to the Central Valley, the high desert or the low desert.

In pots

Kahili ginger grows well in a large, deep pot filled with a humus-rich mix that drains. Its tall stems and big leaves pull water from a pot fast in warm weather. Check the mix 2 inches down every few days in summer, and daily during South Inland heat. Water until it drains from the holes, then empty the saucer. Keep the pot in light shade. Once the stems are cut back at the end of the season, let the mix dry more between waterings until new growth starts. Divide crowded rhizomes in spring.

1 Your climate zone six WUCOLS zones, each from its own reference city
Not ratedWUCOLS does not rate Kahili Ginger for the Central Valley zone
A year
no figure
Reference
Sacramento climate table
Counts
Plant need, before sprinkler losses

WUCOLS lists Kahili Ginger as not suited to this region for the Central Valley zone, so no monthly figure is computed here.

Monthly water need by climate zone

Kahili Ginger: gallons per square foot per month, by WUCOLS climate zone

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.37–1.241.24––
Feb0.53–1.291.39––
Mar0.87–1.842.08––
Apr1.18–2.232.58––
May1.46–2.583.12––
Jun1.61–2.783.67––
Jul1.61–3.174.02––
Aug1.49–2.983.72––
Sep1.24–2.382.98––
Oct0.87–1.842.13––
Nov0.47–1.341.44––
Dec0.31–1.041.09––
Year12–24.829.46––

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 10

Rated not suited to this region in the Central Valley, like Kahili ginger. Plants that drink alike can share one valve and one schedule.

Desert RoseAdenium obesumnot rated, Central Valleyno Central Valley ratingAlpine ToadflaxLinaria alpinanot rated, Central Valleyno Central Valley ratingSkunk CabbageLysichiton americanusnot rated, Central Valleyno Central Valley ratingEgyptian Star FlowerPentas lanceolatanot rated, Central Valleyno Central Valley ratingSwedish IvyPlectranthus verticillatusnot rated, Central Valleyno Central Valley ratingSolomon's SealPolygonatum odoratum (japonicum)not rated, Central Valleyno Central Valley ratingPainted DaisyTanacetum coccineum (Pyrethrum roseum)not rated, Central Valleyno Central Valley ratingWandering JewTradescantia fluminensis (SHADE)not rated, Central Valleyno Central Valley ratingMoses-in-the-CradleTradescantia spathacea (Rhoeo spathacea)not rated, Central Valleyno Central Valley ratingHeath-Leafed BanksiaBanksia ericifolianot rated, Central Valleyno Central Valley rating
Minutes for your sprinklers

Turn this into minutes on your water days

Every city page has a calculator that takes Kahili ginger, 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 Kahili ginger in summer?

In July, established Kahili ginger in loam needs a deep watering about every 5 days on the south coast and about every 4 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 Kahili ginger need per day?

In July on the north-central coast, established Kahili ginger needs about 0.2 gallons a day for a plant 2 feet across and about 0.7 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 Kahili ginger change across California?

Yes. WUCOLS rates Kahili ginger separately for each of the six California climate zones: moderate water in the North-Central Coastal zone, not suited to this region in the Central Valley zone, high water in the South Coastal zone, high 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 Kahili ginger invasive?

It has escaped from gardens and become a serious pest in Hawaii, New Zealand, the Azores and several other regions. It is listed among the world's 100 worst invasive alien species. Cut off spent flower spikes before the seed capsules ripen, and keep the clump away from wild land.

Should I cut back Kahili ginger after it flowers?

Yes. Cut the old flower spikes and the spent foliage at the end of the season. New stems grow from the rhizomes the following year.

Can Kahili ginger take full sun?

It grows in sun or part shade, but it prefers light shade. Full sun dries the soil faster. In hot weather, check the soil more often in a sunny spot.

Is Kahili ginger frost hardy?

It is hardy to roughly 10 to 20 degrees F. Frost kills the foliage back, and the plant regrows from its rhizomes. A deep mulch over the rhizomes helps in colder spots.

When should I divide Kahili ginger?

Divide crowded clumps in spring. Replant pieces that carry healthy rhizome, and water them in well. Keep the soil evenly moist while the new pieces root.

Are Kahili ginger flowers fragrant?

Yes. The lemon-yellow flowers are fragrant, with long red stamens. They open in late summer and early fall on dense spikes at the tops of the stems.

More plant watering guides

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Sources