WateringTimesWatering plan, $19
Alnus cordata, WUCOLS IV

How often to water Italian alder in California

In July in the Central Valley, established Italian alder 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. Italian alder is a fast-growing deciduous tree from Corsica and southern Italy, upright and pyramidal, usually 35 to 40 feet tall. It has shiny, deep green toothed leaves, long male catkins in winter and small woody cones. Like other alders it loves moisture, though its shallow roots are more restrained than those of the native white alder.

TreeRated for 4 of 6 zones

How often to water Italian alder, 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 Italian alder 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 several inches down under the canopy in summer means this moisture-loving tree is due for a deep soak
  • Roots surfacing in a lawn point to frequent shallow watering, since deep soaks keep alder roots lower
  • Puddles lingering for days at the base mean more water than the soil can absorb, even for a wet-tolerant alder
  • Leaf edges browning in a hot, dry spell can indicate the roots have dried out
  • Sticky leaves with small insects point to aphids or alder sucker rather than a watering problem

How to water it

  • Water deeply and less often, wetting the soil about 18 inches down so roots grow downward
  • Spread the water across the whole root zone with a soaker ring or a drip grid
  • Plant in sun or shade in moist soil, including clay and poorly drained spots
  • Keep it away from pipes and paving, since its shallow roots can still be invasive
  • Widen the watered area as the canopy spreads

Through the seasons

Water a young tree regularly through its first summers while roots spread. Leaves drop in fall, and catkins hang from the bare branches in winter. As a moisture-loving tree, it needs regular deep soaks through the dry season, and deep watering also keeps its roots from surfacing. On the coast and in the Central Valley, winter storms normally water the leafless tree. Italian alder carries a moderate water rating in four zones: the north-central coast, the Central Valley, the south coast and South Inland. WUCOLS marks it as not suited to the high desert or the low desert.

In pots

Italian alder grows quickly into a 35 to 40 foot tree, so a container suits only a young plant waiting to go in the ground. Use a deep nursery pot with drainage holes and a moisture-holding mix. On hot days, feel the mix every day and water before the top inch dries, since alders love moisture. Let the water drain, then empty the saucer. Plant it out within a season or two, before roots circle.

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

Italian Alder: 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 Italian alder. 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 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

Similar plants that need less water 16

Rated lower than Italian alder 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 Italian alder, 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 Italian alder in summer?

In July, established Italian alder 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 Italian alder need per day?

In July in the Central Valley, established Italian alder 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 Italian alder change across California?

Yes. WUCOLS rates Italian alder 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.

Do Italian alder roots cause problems?

Its roots are shallow and can be invasive, though more restrained than white alder's. Deep, less frequent watering helps prevent surface root problems. Keep it away from pipes, paving and foundations.

Can Italian alder grow in wet soil?

Yes. It thrives in moist soil and tolerates poor drainage, and it can make a fast-growing screen on wet sites. Alders are noted for handling poor, wet ground.

Is Italian alder a good screen tree?

Yes. Its upright, columnar shape and fast growth suit tall screens and hedges. Plant a row and water deeply while the trees establish.

How tall does Italian alder get?

In gardens it usually reaches 35 to 40 feet tall and 20 to 25 feet wide. It grows fast, so allow room for the mature size.

Can you overwater Italian alder?

Overwatering is less of a risk than drought for this moisture-loving tree. The bigger problem is frequent shallow watering, which pulls roots to the surface.

More plant watering guides

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Sources