WateringTimesWatering plan, $19
Acer japonicum, WUCOLS IV

How often to water fernleaf maple in California

In July in the Central Valley, established fernleaf maple in loam needs a deep watering about every 8 days: about 55 gallons each time under a 10 foot canopy, about 47 gallons a week. Fernleaf maple is the deeply cut, fernlike form of fullmoon maple. That slow-growing deciduous tree or large shrub comes from the mountains of Japan, Korea and Manchuria. It often grows several trunks with smooth gray bark, and its leaves turn yellow and red in fall. It wants cool summers, dappled shade and soil that stays moist but drains.

TreeRated for 2 of 6 zones

How often to water fernleaf maple, 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 fernleaf maple 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 3 inches down under the canopy in summer signals that fernleaf maple needs a deep soak
  • Leaf edges browning and curling in hot sun or dry wind point to scorch, which shade and steady moisture help prevent
  • Leaves wilting by midafternoon and still limp the next morning point to a root zone that has dried too far
  • Yellowing leaves in early summer over soil that stays soggy point to poor drainage rather than thirst

How to water it

  • Water slowly over the root zone out to the edge of the canopy with drip or a soaker hose
  • Soak the soil 12 to 18 inches deep, then let the top few inches dry before the next soak
  • Plant in dappled or afternoon shade, sheltered from strong wind, in moist, well-drained soil
  • Keep 2 to 3 inches of shredded bark over the roots to hold moisture and keep them cool, clear of the trunks
  • Extend the watered area outward as the canopy widens over the years

Through the seasons

A new fernleaf maple needs evenly moist soil through its first two summers while roots spread. Established trees still need deep soakings through the dry season, since heat and dry soil can scorch the leaves. Flowers open in early spring before the leaves, and fall brings yellow and red color before leaf drop. Winter rain covers the dormant months on the north-central coast and in the Central Valley. WUCOLS rates fernleaf maple moderate water on the north-central coast and in the Central Valley. It is marked not suited to South Inland and the low desert. WUCOLS has not evaluated it for the south coast or the high desert.

In pots

Fernleaf maple grows slowly and can live for years in a large, wide container, which suits small gardens. Check the mix 2 inches down every few days in summer, and daily in a heat wave. Water until it flows from the drainage holes, then empty the saucer. Keep the pot in afternoon shade and out of drying wind. In winter the leafless tree needs only enough water to keep the mix from drying out.

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

Fernleaf Maple: gallons per square foot per month, by WUCOLS climate zone

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.370.4––––
Feb0.530.65––––
Mar0.871.09––––
Apr1.181.52––––
May1.462.08––––
Jun1.612.48––––
Jul1.612.67––––
Aug1.492.39––––
Sep1.241.8––––
Oct0.871.18––––
Nov0.470.56––––
Dec0.310.34––––
Year1217.11––––

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 fernleaf maple. Plants that drink alike can share one valve and one schedule.

Citrus TreesCitrus spp.moderate water, Central Valley2.67 gal/sq ft in JulyJapanese MapleAcer palmatummoderate water, Central Valley2.67 gal/sq ft in JulyAvocado TreesPersea americanamoderate water, Central Valley2.67 gal/sq ft in JulyMagnolia TreesMagnolia grandiflora ssp. & cvs.moderate water, Central Valley2.67 gal/sq ft in JulyPalm TreesSyagrus romanzoffiana (Arecastrum romanzoffianum)moderate water, Central Valley2.67 gal/sq ft in JulyApple TreesMalus spp. (edible) e.g, 'Anna' (low chill variety for low desert)moderate water, Central Valley2.67 gal/sq ft in JulyPeach TreesPrunus spp. ediblemoderate water, Central Valley2.67 gal/sq ft in JulyPersimmon TreesDiospyros kakimoderate water, Central Valley2.67 gal/sq ft in JulyAmur MapleAcer ginnalamoderate water, Central Valley2.67 gal/sq ft in JulyBox ElderAcer negundomoderate water, Central Valley2.67 gal/sq ft in JulyNorway MapleAcer platanoidesmoderate water, Central Valley2.67 gal/sq ft in JulyRed MapleAcer rubrummoderate water, Central Valley2.67 gal/sq ft in JulyChinese MapleAcer truncatummoderate water, Central Valley2.67 gal/sq ft in JulyRed BuckeyeAesculus paviamoderate water, Central Valley2.67 gal/sq ft in JulyRed HorsechestnutAesculus x carneamoderate water, Central Valley2.67 gal/sq ft in JulyItalian AlderAlnus cordatamoderate water, Central Valley2.67 gal/sq ft in July

Similar plants that need less water 16

Rated lower than fernleaf maple in the Central Valley. Worth a look for a new bed or a lawn replacement.

Olive TreesOlea europaea ssp. & cvs.low water, Central Valley1.07 gal/sq ft in JulyFig TreesFicus carica ssp. & cvs.low water, Central Valley1.07 gal/sq ft in JulyCrape MyrtleLagerstroemia spp., hybrids & cvs.low water, Central Valley1.07 gal/sq ft in JulyAloeAloe spp. & cvs.low water, Central Valley1.07 gal/sq ft in JulyPomegranate TreesPunica granatumlow water, Central Valley1.07 gal/sq ft in JulyEucalyptusEucalyptus polyanthemoslow water, Central Valley1.07 gal/sq ft in JulyPine TreesPinus canariensislow water, Central Valley1.07 gal/sq ft in JulyJunipersJuniperus spp. & cvs.low water, Central Valley1.07 gal/sq ft in JulyTexas Red OakQuercus buckleyilow water, Central Valley1.07 gal/sq ft in JulyPortuguese OakQuercus faginealow water, Central Valley1.07 gal/sq ft in JulySoapbark TreeQuillaja saponarialow water, Central Valley1.07 gal/sq ft in JulyNecklace TreeSophora affinislow water, Central Valley1.07 gal/sq ft in JulyBailey AcaciaAcacia baileyanalow water, Central Valley1.07 gal/sq ft in JulySilver WattleAcacia dealbatalow water, Central Valley1.07 gal/sq ft in JulyGreen WattleAcacia decurrenslow water, Central Valley1.07 gal/sq ft in JulySydney Golden WattleAcacia longifolialow 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 fernleaf maple, 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 fernleaf maple need per day?

In July in the Central Valley, established fernleaf maple needs about 6.8 gallons a day under a 10 foot canopy and about 27 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 fernleaf maple change across California?

Yes. WUCOLS rates fernleaf maple separately for each of the six California climate zones: moderate water in the North-Central Coastal zone, moderate water in the Central Valley zone, not evaluated in the South Coastal zone, not suited to this region in the South Inland zone, not evaluated 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.

Why are my fernleaf maple leaves scorching?

Hot sun, dry wind or a dry root zone can brown the finely cut leaves. Give the tree afternoon shade and shelter from wind, and check the soil a few inches down. Scorched leaves stay brown, but next spring's leaves can come in clean.

Can fernleaf maple grow in full sun?

It tolerates full sun where summers stay cool. In hot inland summers the leaves may scorch, so dappled or afternoon shade is safer there.

How big does fernleaf maple get?

It grows slowly into a small tree or large shrub, often with several trunks. The species can reach 15 to 30 feet in time. Plan its watering ring for that mature spread.

When does fernleaf maple bloom?

Small purplish-red flowers hang in clusters in early spring, before the leaves open. They are easy to miss. Start checking soil moisture as the new leaves unfold.

Should I stake a young fernleaf maple?

Staking a young tree helps it grow more upright. Loosen and remove the ties once the trunk can stand on its own. Staking does not change how you water it.

More plant watering guides

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Sources