WateringTimesWatering plan, $19
Banksia integrifolia, WUCOLS IV

How often to water tree banksia in California

In July on the north-central coast, established tree banksia in loam needs a deep soak only about once a month or less: about 55 gallons each time under a 10 foot canopy. Tree banksia, also called coast banksia, is a fast-growing evergreen tree from the coastal dunes and mountains of eastern Australia, 20 to 45 feet tall. Its dark green, lance-shaped leaves are silvery gray underneath. From fall to spring, upright, cylinder-shaped cones of pale yellow flowers stand among the leaves, then turn into woody seed clusters.

ShrubTreeRated for 3 of 6 zones

How often to water tree banksia, month by month

Your city
Canopy width
10 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 tree banksia 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 under the branches, 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 canopy width

A tree with its canopy width marked across the widest branches and the circle under it shaded blue

Measure across the branches, from the tips of the outer leaves on one side to the tips on the other. A tape works, or pace it out.

Water the whole circle under the branches, shown in blue. The gallons here cover that circle.

A wider canopy means more gallons each watering, not more waterings. While the tree is young, measure again each spring.

How to tell it needs water

  • A spade pushed in beside a first-year tree turning up dusty soil means tree banksia is due a slow, deep drink
  • Yellow leaves and dying twigs where sprinklers keep the ground wet point to roots that are drowning
  • Leaves on a sapling curling in a dry east wind can mean it went too dry
  • Spent flower cones turning into woody seed clusters is normal

How to water it

  • Build a basin and fill it slowly for a young tree, then let it drain and dry
  • Near the coast, an established tree needs only an occasional soak; inland it needs a bit more
  • Give it sun or part shade and almost any soil that drains
  • It handles salt wind on the coast, where it grows wild on dunes
  • Give it space for a broad crown

Through the seasons

Give a young tree deep water through its first summers while roots spread. After that, it needs only an occasional soak near the coast and a little more inland. The cylinder-shaped flower cones appear from fall to spring. Tree banksia carries a low water rating from WUCOLS on the north-central coast and the south coast. For South Inland the rating is moderate water. WUCOLS marks it as not suited to the Central Valley or the high desert. The low desert has no WUCOLS evaluation for it.

In pots

Tree banksia grows fast, so a container suits only a young plant for a season or two. Choose a deep pot and a lean, gritty mix. Soak it whenever the upper few inches have dried, and let all the water run out. Summer heat calls for a check twice a week. Tip out any water left below the pot. Move it into the ground early, in a sunny spot with room for a tree.

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

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

Monthly water need by climate zone

Tree Banksia: gallons per square foot per month, by WUCOLS climate zone

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.15–0.310.78––
Feb0.21–0.320.87––
Mar0.35–0.461.3––
Apr0.47–0.561.61––
May0.58–0.641.95––
Jun0.64–0.692.29––
Jul0.64–0.792.51––
Aug0.6–0.742.33––
Sep0.5–0.61.86––
Oct0.35–0.461.33––
Nov0.19–0.330.9––
Dec0.12–0.260.68––
Year4.8–6.218.41––

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

Chenille PlantAcalypha hispidanot rated, Central Valleyno Central Valley ratingCopperleafAcalypha wilkesiananot rated, Central Valleyno Central Valley ratingSugar MapleAcer saccharumnot rated, Central Valleyno Central Valley ratingQueensland KauriAgathis robustanot rated, Central Valleyno Central Valley ratingCherimoyaAnnona cherimolanot rated, Central Valleyno Central Valley ratingYellow Bell BauhiniaBauhinia tomentosanot rated, Central Valleyno Central Valley ratingPurple Orchid TreeBauhinia variegata (purpurea)not rated, Central Valleyno Central Valley ratingToogBischofia javanicanot rated, Central Valleyno Central Valley ratingMagic FlowerCantua buxifolianot rated, Central Valleyno Central Valley ratingClustered Fishtail PalmCaryota mitisnot rated, Central Valleyno Central Valley ratingWhite SapoteCasimiroa edulisnot rated, Central Valleyno Central Valley ratingHawaiian TiCordyline fruticosa (Cordyline terminalis)not rated, Central Valleyno Central Valley ratingFilbertCorylus maximanot rated, Central Valleyno Central Valley ratingSpotted GumCorymbia maculata (Eucalyptus maculata)not rated, Central Valleyno Central Valley ratingDove TreeDavidia involucratanot rated, Central Valleyno Central Valley ratingRoyal PoincianaDelonix regianot 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 tree banksia, 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 tree banksia in summer?

In July, established tree banksia in loam needs a deep watering about every 27 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 tree banksia need per day?

In July on the north-central coast, established tree banksia needs about 1.6 gallons a day under a 10 foot canopy and about 6.5 gallons a day under a 20 foot canopy. Give it in deep waterings spread days apart rather than a little every day, so the whole root zone gets wet.

Does watering for tree banksia change across California?

Yes. WUCOLS rates tree banksia separately for each of the six California climate zones: low water in the North-Central Coastal zone, not suited to this region in the Central Valley zone, low 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 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 tree banksia good near the ocean?

Yes, it is native to coastal dunes in eastern Australia. It is adaptable to most soils. It suits coastal gardens.

When does tree banksia bloom?

Pale yellow flower cones appear from fall to spring. Woody seed clusters follow. The cones stand upright among the leaves.

How big does tree banksia get?

It grows fast to 20 to 45 feet tall and 15 to 30 feet wide. It can be shrubby when young. Give it room.

What soil does tree banksia need?

It is adaptable to most soils. Drainage matters more than fertility. Skip heavy feeding.

Why are the leaves silver underneath?

The leaves are dark green above and silvery gray beneath. They flash silver in wind. That is normal.

More plant watering guides

Monterey PineSwedish IvySolomon's SealQuaking AspenShaving Brush TreeCommon GuavaFlame VineNikau Palm

Sources