WateringTimesWatering plan, $19
Acer macrophyllum, WUCOLS IV

How often to water big leaf maple in California

In July in the Central Valley, established big leaf maple in loam needs a deep watering about every 5 days: about 55 gallons each time under a 10 foot canopy, about 76 gallons a week. Big leaf maple is a native deciduous tree of moist woods and streamsides in the coast ranges and northern Sierra. It is the most massive maple in North America, commonly 40 to 75 feet tall and wide, with huge leaves that cast deep shade. It prefers moist, well-drained soil and cool summers, and its shallow roots can crack paving.

TreeCalifornia nativeRated for 4 of 6 zones

How often to water big leaf 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 big leaf 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 a foot down under the canopy in summer signals big leaf maple needs a deep soak
  • Large leaves browning at the edges in hot weather can indicate drought stress or heat
  • Leaves dropping early in late summer can follow a long dry spell
  • Yellowing leaves and thin growth over waterlogged soil suggest poor drainage

How to water it

  • Water broadly under the canopy and beyond with soakers, not just at the trunk
  • Soak 18 inches deep, then let the top few inches dry before the next soak
  • Plant in moist, slightly acidic, well-drained soil in sun or part shade
  • Keep it well away from sidewalks, drives and foundations
  • Mulch the root zone and widen watering as the crown grows

Through the seasons

Water a young big leaf maple deeply through its first summers. Established trees still want moisture through summer, since they come from streamsides and moist woods. It is deciduous, dropping its large leaves in fall and resting through winter, when rain covers its needs. WUCOLS rates big leaf maple moderate water on the north-central coast and the south coast. In the Central Valley and South Inland it carries a high water rating. WUCOLS marks it as not suited to the high desert or the low desert.

In pots

Big leaf maple becomes a huge tree and only suits a container while very young. Grow a seedling in a deep pot of rich mix for a year or so. Water when the top inch or two dries and let it drain. In summer, a small pot may need water daily. Empty the saucer. After leaf drop, water lightly until spring. Plant it out early, since its roots spread wide and shallow.

1 Your climate zone six WUCOLS zones, each from its own reference city
4.27gal per sq ft in JulyHigh water use in the Central Valley zone
A year
27.38 gal per sq ft
Reference
Sacramento climate table
Counts
Plant need, before sprinkler losses
1.12.13.24.30.64JAN1.04FEB1.74MAR2.43APR3.32MAY3.97JUN4.27JUL3.82AUG2.88SEP1.88OCT0.89NOV0.55DEC1.12.13.24.30.64JFM2.43AMJ4.27JAS1.88OND
Gallons per square foot per month, Central Valley. Peak 4.27 in Jul, 27.38 a year.

Monthly water need by climate zone

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

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.370.640.781.24––
Feb0.531.040.811.39––
Mar0.871.741.152.08––
Apr1.182.431.42.58––
May1.463.321.613.12––
Jun1.613.971.743.67––
Jul1.614.271.984.02––
Aug1.493.821.863.72––
Sep1.242.881.492.98––
Oct0.871.881.152.13––
Nov0.470.890.841.44––
Dec0.310.550.651.09––
Year1227.3815.529.46––

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 16

Rated high water in the Central Valley, like big leaf maple. Plants that drink alike can share one valve and one schedule.

White AlderAlnus rhombifoliahigh water, Central Valley4.27 gal/sq ft in JulyRed AlderAlnus rubra (Alnus oregona)high water, Central Valley4.27 gal/sq ft in JulyRiver BirchBetula nigrahigh water, Central Valley4.27 gal/sq ft in JulyWater BirchBetula occidentalishigh water, Central Valley4.27 gal/sq ft in JulyEuropean White BirchBetula pendulahigh water, Central Valley4.27 gal/sq ft in JulyWhite-Barked Himalayan BirchBetula utilis var. jacquemontiihigh water, Central Valley4.27 gal/sq ft in JulyEuropean BeechFagus sylvaticahigh water, Central Valley4.27 gal/sq ft in JulyBlack CottonwoodPopulus trichocarpa (Populus balsamifera)high water, Central Valley4.27 gal/sq ft in JulyCarolina PoplarPopulus x canadensishigh water, Central Valley4.27 gal/sq ft in JulyWeeping WillowSalix babylonicahigh water, Central Valley4.27 gal/sq ft in JulyPeking WillowSalix matsudanahigh water, Central Valley4.27 gal/sq ft in JulyCoast RedwoodSequoia sempervirenshigh water, Central Valley4.27 gal/sq ft in JulyVine MapleAcer circinatumhigh water, Central Valley4.27 gal/sq ft in JulyHydrangeaHydrangea macrophylla & cvs.high water, Central Valley4.27 gal/sq ft in JulyBlueberriesVaccinium hybrids and cvs (CA native and non- native spp.)high water, Central Valley4.27 gal/sq ft in JulyShell GingerAlpinia zerumbethigh water, Central Valley4.27 gal/sq ft in July

Similar plants that need less water 16

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

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 JulyFernleaf MapleAcer japonicummoderate 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 July
Minutes for your sprinklers

Turn this into minutes on your water days

Every city page has a calculator that takes big leaf 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 often should I water big leaf maple in summer?

In July, established big leaf maple in loam needs a deep watering about every 5 days in the Central Valley, about every 11 days on the south coast and about every 5 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 big leaf maple need per day?

In July in the Central Valley, established big leaf maple needs about 11 gallons a day under a 10 foot canopy and about 43 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 big leaf maple change across California?

Yes. WUCOLS rates big leaf maple separately for each of the six California climate zones: moderate water in the North-Central Coastal zone, high water in the Central Valley zone, moderate 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.

Will big leaf maple roots crack my driveway?

They can. Its shallow, spreading roots can crack sidewalks and driveways. Plant it far from paving and water deeply.

How big does big leaf maple get?

It usually grows 40 to 75 feet tall and wide, making it the most massive North American maple. Plant it only in large yards or parks. Its leaves are very large.

Can big leaf maple handle hot summers?

It prefers cool summers like those of its native range. Hot inland summers stress it, so keep deep soaks steady. Young trees appreciate afternoon shade.

Is big leaf maple native to California?

Yes, it is native along the West Coast, from Alaska into California. Here it favors stream banks and moist woods at lower elevations. It suits native gardens with plenty of room.

Why is my maple covered in moss?

In moist coastal forests, its trunks often carry mosses, lichens and ferns. They do not harm the tree. Moss is a sign of humid air, not a watering problem.

More plant watering guides

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Sources