WateringTimesWatering plan, $19
Acer negundo, WUCOLS IV

How often to water box elder in California

In July in the Central Valley, established box elder 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. Box elder is a fast growing deciduous maple, usually 30 to 50 feet tall. Its compound leaves carry three to five leaflets instead of the familiar maple shape. A California form grows wild in the mountains of central and northern California, nearly always near water. It needs moisture while young and does best with deep soakings through dry summers.

TreeCalifornia nativeRated for 4 of 6 zones

How often to water box elder, 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 box elder 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 beneath the canopy edge signals that box elder needs a deep soak
  • Leaves scorching at the margins or dropping early in summer heat can indicate a dry root zone
  • Swarms of small bugs on seed bearing branches are usually boxelder bugs, which feed on seeds and do little other harm
  • A white powdery coating or spotted, browning leaves point to powdery mildew or anthracnose rather than thirst
  • Persistent yellowing in soil that stays soggy and airless can indicate poor drainage, despite its tolerance of seasonal flooding

How to water it

  • Water a young box elder over its root ball and the surrounding soil so the ball stays moist while roots spread
  • Shift water to the outer canopy and beyond as the tree grows, wetting the soil a foot or more deep
  • Spread leaf litter or wood chips over the root zone to hold the moisture it favors
  • Plant in anything from gravel to adobe clay, choosing a spot where runoff or a low swale adds moisture
  • Let the top few inches of soil dry between soakings once the tree is established

Through the seasons

A young box elder needs moisture at first, so keep its root area damp through the first summers. Established trees still want deep soakings through the dry months, since in the wild they grow near streams. WUCOLS rates box elder moderate water on the north-central coast, in the Central Valley, on the south coast and in South Inland. WUCOLS marks it as not suited to the high desert or the low desert. Leaves drop in fall, and winter rain usually covers the bare tree on the coast and in the Central Valley. Seasonal flooding does not trouble it, but strong wind can snap its weak branches.

In pots

Box elder grows fast, so a pot only suits a young tree for a season or two. Use a large container with drainage holes and a mix that holds moisture. In summer heat, check the mix often and water before it dries more than an inch or two down. Water until it drains, then tip out the saucer. After the leaves drop, water lightly but keep the mix from drying out. Plant it in the ground early, while its roots are still small.

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

Box Elder: gallons per square foot per month, by WUCOLS climate zone

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.370.40.780.78––
Feb0.530.650.810.87––
Mar0.871.091.151.3––
Apr1.181.521.41.61––
May1.462.081.611.95––
Jun1.612.481.742.29––
Jul1.612.671.982.51––
Aug1.492.391.862.33––
Sep1.241.81.491.86––
Oct0.871.181.151.33––
Nov0.470.560.840.9––
Dec0.310.340.650.68––
Year1217.1115.518.41––

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 moderate water in the Central Valley, like box elder. 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 JulyFernleaf MapleAcer japonicummoderate 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 box elder 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 box elder, 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 box elder in summer?

In July, established box elder in loam needs a deep watering about every 8 days in the Central Valley, about every 11 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 box elder need per day?

In July in the Central Valley, established box elder 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 box elder change across California?

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

What are the bugs all over my box elder?

They are most likely boxelder bugs, which feed on the seeds of female trees. They cause little damage to the tree itself. More water will not get rid of them.

Is box elder messy?

Female trees produce seeds that draw boxelder bugs, so male trees are tidier. Its fast growing wood is weak and brittle, and branches can break in strong wind. Plant it away from roofs and parking spots.

Is box elder a California native?

Yes. Its California variety is native to mountain areas from central to northern California, usually beside a stream or other water source. It tolerates sand, clay and seasonal flooding.

Why does my box elder look like poison ivy?

Its compound leaves often carry three leaflets, which can resemble poison ivy. Box elder is a tree, and its leaves sit opposite each other on the twigs. Check the leaf arrangement before pulling a seedling.

Can you overwater a box elder?

It tolerates seasonal flooding and prefers moist ground, so it handles more water than most trees. Still, soil that never drains can harm the roots. Let the surface dry slightly between deep soakings.

More plant watering guides

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Sources