WateringTimesWatering plan, $19
Aesculus x carnea, WUCOLS IV

How often to water red horsechestnut in California

In July in the Central Valley, established red horsechestnut 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. Red horsechestnut is a slow-growing deciduous shade tree with large, hand-shaped leaves and upright pink to red flower clusters in mid-spring. It prefers moist, fertile soil with good drainage. Dry conditions scorch its leaves, so it needs steady deep soakings through the warm months.

TreeRated for 4 of 6 zones

How often to water red horsechestnut, 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 red horsechestnut 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

  • A trowel's depth of dry soil, 4 to 6 inches down near the canopy edge, means red horsechestnut needs a deep soak
  • Brown, crisp leaf edges in summer point to scorch from dry conditions
  • Large brown blotches on the leaves point to leaf blotch disease, which watering alone does not cure
  • Leaves wilting by midday over dry ground on a young tree warrant a check of the root ball
  • Pale, yellowing leaves while the ground stays soggy suggest the roots are short of air

How to water it

  • Water red horsechestnut across the root zone under the canopy and beyond it with drip or a slow soaker
  • Run water slowly until the soil is moist 18 inches down, then wait for the top few inches to dry
  • Spread wood chip mulch over the root zone to keep the soil cool, leaving the trunk flare clear
  • Plant in fertile soil with good drainage, avoiding spots where water stands after irrigation
  • Shift drip lines outward as the canopy widens, since feeding roots extend past the branch tips

Through the seasons

Keep a new red horsechestnut evenly moist through its first summers while roots spread, widening the wet area each year. Established trees still need deep soakings in dry weather, since dry soil causes leaf scorch. Leaves unfold in spring, flowers follow in mid-spring, and the tree drops its leaves in fall. Irrigation matters most from leaf out through the end of summer. Winter rain covers the dormant months on the coast and in the Central Valley in most years. WUCOLS rates red horsechestnut 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.

In pots

Red horsechestnut matures into a 30 to 40 foot tree, so a pot only works for a young tree before planting out. Use a deep container with drainage holes and check the mix 2 inches down every few days in summer heat. Water until excess runs from the bottom, then empty the saucer. A potted tree dries fast on a hot patio, and its leaves scorch quickly when the mix dries out. In winter the tree is leafless and needs only enough water to keep the root ball from drying.

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

Red Horsechestnut: 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 red horsechestnut. 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 JulyItalian AlderAlnus cordatamoderate water, Central Valley2.67 gal/sq ft in July

Similar plants that need less water 16

Rated lower than red horsechestnut 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 red horsechestnut, 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 red horsechestnut in summer?

In July, established red horsechestnut 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 red horsechestnut need per day?

In July in the Central Valley, established red horsechestnut 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 red horsechestnut change across California?

Yes. WUCOLS rates red horsechestnut 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.

Are red horsechestnut seeds poisonous?

Yes. The glossy nuts inside the brown husks are poisonous and can cause vomiting and diarrhea if eaten. Rake them up in fall where children and pets play.

Why are my red horsechestnut leaves brown at the edges?

Dry conditions commonly scorch its leaves. Check moisture well below the surface and soak deeply if it is dry. Leaf blotch, a fungal disease, causes larger brown patches and needs separate attention.

Does red horsechestnut attract hummingbirds?

Yes. Its pink to red spring flowers draw hummingbirds and bees. Spring rain often keeps the soil moist during bloom, so check before adding water.

How fast does red horsechestnut grow?

Slowly. It reaches about 30 to 40 feet tall and 25 to 35 feet wide over many years. Its root zone grows with it, so move irrigation outward as the canopy widens.

Can you overwater red horsechestnut?

Yes. It likes moist soil, but it also needs good drainage. Soil that stays saturated starves roots of air, so let the top few inches dry between soakings.

Is red horsechestnut messy?

Its seed pods drop in fall and can litter paths and patios. Plant it away from paving and keep the ground under it mulched. Raking the husks off the mulch is easier than off lawn.

More plant watering guides

Bushy ClematisHarlequin GlorybowerSakakiLily of the ValleyEddie's White Wonder DogwoodRed-Barked DogwoodBunchberryEvergreen Dogwood

Sources