WateringTimesWatering plan, $19
Catalpa bignonioides, WUCOLS IV

How often to water bean tree in California

In July in the Central Valley, established bean tree 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. Bean tree, better known as southern catalpa, is a fast-growing deciduous shade tree with huge heart-shaped leaves. White trumpet flowers are followed by long, thin pods. It is tough about heat, cold and clay, and it copes with both wet and dry spells. It still does best with moderate, regular water and shelter from strong wind.

TreeRated for 4 of 6 zones

How often to water bean tree, 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 bean tree 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 inches down at the edge of a young catalpa's root ball means it is ready for a deep soak
  • Big leaves wilting by midafternoon and still limp in the evening point to a thirsty tree
  • Leaves yellowing over soil kept constantly wet can mean the roots are short of air, even for this flood-tolerant tree
  • Leaves stripped in summer by large caterpillars come from the catalpa sphinx moth, which rarely kills the tree
  • Torn, ragged leaves after a windy spell or hail are weather damage, not a watering problem

How to water it

  • Water a young bean tree deeply over the root ball and well beyond it, widening the ring each year
  • Give established trees regular deep soakings through summer, letting the top few inches dry between them
  • Plant in full sun or light shade, sheltered from strong wind that shreds the big leaves
  • Use almost any soil, from clay to sand, since this tree adapts widely
  • Spread mulch over the root zone, and rake fallen pods and leaves off the drip lines

Through the seasons

Water a new bean tree regularly through its first two summers, then switch to deep soakings timed to the soil drying. The big leaves come out in spring, white trumpet flowers open in late spring and early summer, and long, thin pods follow. Leaves drop in fall, and the bare tree needs little water through winter, when rain covers the coast and the Central Valley. Moderate water is its WUCOLS rating on the south coast, on the north-central coast, in South Inland and in the Central Valley. The low desert and the high desert have not been evaluated.

In pots

Bean tree grows fast into a big shade tree, so a pot only suits a young tree. A grafted dwarf standard of 'Nana' can stay in a large container much longer. In summer, check the mix 2 to 3 inches down every couple of days and water when it has dried to that depth. Let the water run out of the bottom, then pour off the saucer. The big leaves lose water fast in hot wind, so shelter the pot. In winter the bare tree needs little.

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

Bean Tree: 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 bean tree. 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 bean tree 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 bean tree, 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 bean tree in summer?

In July, established bean tree 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 bean tree need per day?

In July in the Central Valley, established bean tree 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 bean tree change across California?

Yes. WUCOLS rates bean tree 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 evaluated in the High and Intermediate Desert zone, not evaluated in the Low Desert zone. The monthly table above shows how the same rating translates into different gallon amounts as reference evapotranspiration changes.

Is bean tree the same as catalpa?

Yes. Bean tree, cigar tree and southern catalpa are all names for Catalpa bignonioides. The first two come from its long, thin seed pods.

What is eating my catalpa leaves?

Catalpa sphinx caterpillars can strip a tree in summer, though they rarely kill it. Pick them off small trees by hand. Watering changes will not stop them.

Why are my catalpa leaves torn?

Wind and hail shred the big leaves easily. Plant it where it is sheltered from strong wind. Torn leaves do not mean the tree needs more water.

Is bean tree messy?

Flowers, long pods and big leaves each drop in their season, and the winged seeds can sprout nearby. Plant it away from patios and pull seedlings while they are small.

Can bean tree handle wet soil?

Yes. It tolerates clay and both wet and dry conditions, even seasonal flooding, which suits it to rain gardens. Regular deep soakings still suit it best through dry summers.

More plant watering guides

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Sources