WateringTimesWatering plan, $19
Populus alba 'Pyramidalis', WUCOLS IV

How often to water bolleana poplar in California

In July in the Central Valley, established bolleana poplar 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. Bolleana poplar is an upright, fast-growing form of white poplar with leaves that are dark green above and pale, felted white beneath, flashing silver in the wind. Its whitish bark resembles a birch trunk more than a typical poplar. Established trees tolerate moderate dry spells well outside the desert, but suckers freely from the roots and can colonize nearby ground.

TreeRated for 6 of 6 zones

How often to water bolleana poplar, 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 bolleana poplar 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 beneath an established bolleana poplar signals it needs a deep soak
  • A canopy flashing more of its pale undersides than usual and looking dull overall can accompany dry soil in summer heat
  • Stalled growth on a young tree through a hot season often traces back to a dry root zone
  • Soft bark and yellowing lower leaves on ground that stays soggy for days can point to root rot rather than a nutrient problem
  • A thick stand of new suckers at the base or in nearby lawn reflects this tree's spreading habit rather than a watering problem

How to water it

  • Water the ring of soil beneath the canopy and beyond the branch spread rather than close against the trunk
  • Soak the root zone deeply, then let the top several inches dry before watering again
  • Remove unwanted root suckers as they appear instead of trying to control them through less water
  • Keep mulch over the root zone to slow moisture loss, clear of the trunk
  • Give desert plantings more frequent deep soaking than those in milder zones, matching the higher WUCOLS rating there

Through the seasons

Give a newly planted bolleana poplar steady moisture through its first couple of summers while its fast-spreading roots establish. Established trees handle moderate dry stretches well in milder zones but need more frequent watering in desert heat. This deciduous poplar leafs out in spring and drops its leaves in fall, with water mattering most through the growing season. Winter rain can cover the cool months on the coast and in the Central Valley. WUCOLS rates bolleana poplar moderate water on the north-central coast, in the Central Valley, on the south coast and in South Inland. It rates high water in the high desert and the low desert.

In pots

Bolleana poplar is rarely kept in a container long term, since its vigorous, suckering roots quickly outgrow pot space. A young tree can be held briefly in a large nursery container before planting. Check the mix a couple of inches down often in summer heat and water when dry there, letting water drain fully through the holes. Shade the container from the hottest afternoon sun. Plan to move it into open ground within a season rather than leaving it potted.

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
1.22.43.64.90.4JAN0.65FEB1.09MAR1.52APR2.08MAY2.48JUN2.67JUL2.39AUG1.8SEP1.18OCT0.56NOV0.34DEC1.22.43.64.90.4JFM1.52AMJ2.67JAS1.18OND
Gallons per square foot per month, Central Valley. Peak 2.67 in Jul, 17.11 a year.

Monthly water need by climate zone

Bolleana Poplar: gallons per square foot per month, by WUCOLS climate zone

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.370.40.780.781.191.24
Feb0.530.650.810.871.491.49
Mar0.871.091.151.32.332.43
Apr1.181.521.41.613.033.12
May1.462.081.611.953.823.92
Jun1.612.481.742.294.564.46
Jul1.612.671.982.514.864.56
Aug1.492.391.862.334.464.17
Sep1.241.81.491.863.423.32
Oct0.871.181.151.332.332.38
Nov0.470.560.840.91.491.54
Dec0.310.340.650.681.041.09
Year1217.1115.518.4134.0333.73

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 bolleana poplar. 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 bolleana poplar 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 bolleana poplar, 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 bolleana poplar in summer?

In July, established bolleana poplar 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 bolleana poplar need per day?

In July in the Central Valley, established bolleana poplar 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 bolleana poplar change across California?

Yes. WUCOLS rates bolleana poplar 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, high water in the High and Intermediate Desert zone, high water in the Low Desert zone. The monthly table above shows how the same rating translates into different gallon amounts as reference evapotranspiration changes.

Why does my bolleana poplar need more water in the desert?

WUCOLS rates it high water in the high and low desert, compared with moderate water across the rest of the state. Desert heat and low humidity pull moisture from the wide canopy faster than coastal or valley conditions do. Plan on more frequent deep soaking in a desert planting.

How do I stop bolleana poplar from suckering everywhere?

Cut or mow unwanted suckers as they appear rather than letting them establish into new stems. Reducing water will not reliably stop this habit, since it is rooted in the tree's growth pattern.

Why do bolleana poplar leaves look silver in wind?

The leaf undersides have dense white hairs, which become visible as the foliage moves. This is a normal leaf feature and does not call for extra water.

Can bolleana poplar roots damage pipes or paving?

Its vigorous, wide-spreading roots are a common source of lifted pavement and invaded irrigation lines near the surface. Plant it well away from foundations, walkways and sewer lines. Roots already established nearby will not be redirected by a change in watering.

Is bolleana poplar a good windbreak or screen tree?

Yes, its fast growth and upright form make it a common choice for windbreaks and tall screens. That same density means a row planting needs the same per-tree root spread as a single specimen. Give each tree room, or expect heavier competition for water along the line.

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Sources