WateringTimesWatering plan, $19
Olea africana, WUCOLS IV

How often to water African olive in California

In July on the north-central coast, established African olive in loam needs a deep soak only about once a month or less: about 55 gallons each time under a 10 foot canopy. African olive is a dense evergreen tree, a small-fruited wild relative of the common olive that grows across Africa and into Asia. Its leaves are green with a gold cast above and grayish beneath, and foliage stays thick to the ground. Once established it is very drought tolerant, which makes it a sturdy large screen.

TreeRated for 2 of 6 zones

How often to water African olive, 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 African olive 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

  • Soil dry 4 to 6 inches down at the edge of a young tree's root ball means it is time for a deep soak
  • Wilting shoot tips on a young tree in its first summers, with dry soil below, can mean the root ball dried too far
  • An established tree that stays full and green through a dry summer needs no extra water, since it is very drought tolerant
  • Yellowing leaves over soil that stays wet for days point to poor drainage, since African olive wants well-drained ground

How to water it

  • Water a young African olive over its root ball and a band of soil beyond it, widening the band as the canopy spreads
  • Soak slowly until water reaches about 18 inches down, then let the soil dry well before the next soak
  • Plant in full sun in deep, well-drained soil, where the tree looks its best
  • Spread a thick layer of leaf or wood chip mulch over the root zone, kept clear of the trunk
  • Site the tree well away from walls, patios and pools, since its roots can be aggressive

Through the seasons

Give a new African olive deep soakings through its first summers while its roots spread. Once established, it is very drought tolerant and needs little help. This evergreen holds its leaves all year. Tiny, fragrant flowers open in late winter to spring, and clusters of small round fruits follow. Winter rain covers the cool months on the north-central coast and the south coast, where WUCOLS rates African olive low water. WUCOLS has not evaluated it for the Central Valley, South Inland, the high desert or the low desert. Check young trees during long dry spells in any season.

In pots

African olive is a tree for open ground, though it is also trained as bonsai and can spend its early years in a large pot. Check the mix 2 inches down every few days in summer, and more often in hot, windy weather. Water until it drains from the holes, then empty the saucer. Let the mix dry partly between soakings so the roots never stay soggy. A bonsai in a shallow dish dries fastest and needs a daily look in summer heat. In winter, water only when the mix is dry below the surface.

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

WUCOLS lists African Olive as not evaluated for the Central Valley zone, so no monthly figure is computed here.

Monthly water need by climate zone

African Olive: gallons per square foot per month, by WUCOLS climate zone

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.15–0.31–––
Feb0.21–0.32–––
Mar0.35–0.46–––
Apr0.47–0.56–––
May0.58–0.64–––
Jun0.64–0.69–––
Jul0.64–0.79–––
Aug0.6–0.74–––
Sep0.5–0.6–––
Oct0.35–0.46–––
Nov0.19–0.33–––
Dec0.12–0.26–––
Year4.8–6.2–––

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 evaluated in the Central Valley, like African olive. Plants that drink alike can share one valve and one schedule.

Hawthorn MapleAcer crataegifoliumnot rated, Central Valleyno Central Valley ratingMountain MapleAcer glabrumnot rated, Central Valleyno Central Valley ratingMiyabe MapleAcer miyabeinot rated, Central Valleyno Central Valley ratingEverglades PalmAcoelorraphe wrightiinot rated, Central Valleyno Central Valley ratingPink CedarAcrocarpus fraxinifoliusnot rated, Central Valleyno Central Valley ratingYellowwoodAfrocarpus falcatus (Podocarpus falcatus)not rated, Central Valleyno Central Valley ratingNew Caledonian PineAraucaria columnaris (A. cookii)not rated, Central Valleyno Central Valley ratingFormosa Sugar PalmArenga englerinot rated, Central Valleyno Central Valley ratingNeemAzadirachta indicanot rated, Central Valleyno Central Valley ratingBismarck PalmBismarckia nobilisnot rated, Central Valleyno Central Valley ratingAmerican HornbeamCarpinus caroliniananot rated, Central Valleyno Central Valley ratingJapanese HornbeamCarpinus japonicanot rated, Central Valleyno Central Valley ratingAmerican YellowwoodCladrastis kentukeanot rated, Central Valleyno Central Valley ratingPagoda DogwoodCornus alternifolianot rated, Central Valleyno Central Valley ratingGiant DogwoodCornus controversanot rated, Central Valleyno Central Valley ratingButterfly PalmDypsis lutescens (Areca)not 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 African olive, 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 much water does African olive need per day?

In July on the north-central coast, established African olive 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 African olive change across California?

Yes. WUCOLS rates African olive separately for each of the six California climate zones: low water in the North-Central Coastal zone, not evaluated in the Central Valley zone, low 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.

How is African olive different from a regular olive?

It is a small-fruited subspecies of the common olive. Its flowers and fruits are smaller, its leaves carry a gold cast, and it keeps dense foliage to the ground on a more upright frame. It is grown mainly as a screen.

How big does African olive get?

Expect a dense tree about 20 to 30 feet tall and 15 to 25 feet wide. It grows slowly, so a screen takes years to fill in. Leave room for its full spread at planting.

How much cold can African olive take?

It is rated hardy to about 15 to 20 degrees F. In its South African range it is known as a frost resistant tree.

Are African olive roots invasive?

The roots can be aggressive, so do not plant it close to walls, patios or swimming pools. Give it open ground where a wide root system can spread.

Does African olive grow near the beach?

Yes. It is described as a good seaside plant and a dense screen, and it resists wind. Plant it in full sun and well-drained soil.

Do birds eat African olive fruit?

Yes. In its native range many birds and animals feed on the small fruits, which ripen purple-black. The fruits form in clusters after the tiny flowers.

More plant watering guides

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Sources