How often to water Autumn Splendor horse chestnut in California
In July on the north-central coast, established Autumn Splendor horse chestnut in loam needs a deep watering about every 13 days: about 55 gallons each time under a 10 foot canopy, about 29 gallons a week. Autumn Splendor is a deciduous hybrid buckeye, a cross of yellow, Ohio and red buckeyes, sold under the horse chestnut name. Spring brings upright clusters of yellow flowers marked with red, and fall turns the leaves red to maroon. It wants moist, well drained soil and dislikes dry ground, though an established tree takes drier spells better than most buckeyes.
How often to water Autumn Splendor horse chestnut, month by month
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.
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.
How to tell it needs water
- On a young tree, soil that feels dry 4 inches below the mulch calls for a slow, deep soak
- Leaflets hanging limp late in the day and still soft the next morning point to a dry root zone
- Crisp brown edges on the leaflets in summer suggest too little water is reaching the leaves, since this cultivar normally resists scorch
- Leaves yellowing while the ground stays soggy for days point to poor drainage rather than thirst
How to water it
- Water a young tree over its root ball and a ring of soil just beyond it, widening the ring as the crown spreads
- Run water slowly so it sinks 12 to 18 inches, and feel the top 3 to 4 inches before giving more
- Keep wood chip mulch over the root zone to hold the even moisture this tree prefers, with bare soil left around the trunk
- Plant in well drained loam, never in a hollow where water stands after winter storms
- Move drip emitters out under the low outer branches as an older tree grows, rather than watering at the trunk
Through the seasons
Give a new tree deep soakings through its first two or three summers while roots spread past the planting hole. An established tree takes fewer, deeper waterings and copes with drier spells than other buckeyes, but it is not a dry garden tree. Flower clusters open in spring, and summer soil checks matter most. Fall brings red to maroon color and husked brown nuts, then the bare tree rests through winter. WUCOLS rates it moderate water on the north-central coast, where winter rain covers the cool months. WUCOLS has not evaluated it for the Central Valley, the south coast, South Inland, the high desert or the low desert.
In pots
Autumn Splendor grows into a rounded tree around 25 feet tall and wide, so a container is only a holding stage before planting. Check a nursery can 2 to 3 inches down every few days in summer, and daily during hot inland spells. Water until it drains from the bottom, then empty the saucer. Keep the can off hot paving, since a baked, dry root ball can brown the leaf edges. In winter the bare tree uses little water, so let the mix dry somewhat between waterings.
- A year
- no figure
- Reference
- Sacramento climate table
- Counts
- Plant need, before sprinkler losses
WUCOLS lists Autumn Splendor Horse Chestnut as not evaluated for the Central Valley zone, so no monthly figure is computed here.
Monthly water need by climate zone
Autumn Splendor Horse Chestnut: gallons per square foot per month, by WUCOLS climate zone
| Month | N. Coast | C. Valley | S. Coast | S. Inland | Hi Desert | Lo Desert |
|---|---|---|---|---|---|---|
| Jan | 0.37 | – | – | – | – | – |
| Feb | 0.53 | – | – | – | – | – |
| Mar | 0.87 | – | – | – | – | – |
| Apr | 1.18 | – | – | – | – | – |
| May | 1.46 | – | – | – | – | – |
| Jun | 1.61 | – | – | – | – | – |
| Jul | 1.61 | – | – | – | – | – |
| Aug | 1.49 | – | – | – | – | – |
| Sep | 1.24 | – | – | – | – | – |
| Oct | 0.87 | – | – | – | – | – |
| Nov | 0.47 | – | – | – | – | – |
| Dec | 0.31 | – | – | – | – | – |
| Year | 12 | – | – | – | – | – |
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 not evaluated in the Central Valley, like Autumn Splendor horse chestnut. Plants that drink alike can share one valve and one schedule.
Hawthorn MapleAcer crataegifoliumnot rated, Central Valleyno Central Valley rating
Mountain MapleAcer glabrumnot rated, Central Valleyno Central Valley rating
Miyabe MapleAcer miyabeinot rated, Central Valleyno Central Valley rating
Everglades PalmAcoelorraphe wrightiinot rated, Central Valleyno Central Valley rating
Pink CedarAcrocarpus fraxinifoliusnot rated, Central Valleyno Central Valley rating
YellowwoodAfrocarpus falcatus (Podocarpus falcatus)not rated, Central Valleyno Central Valley rating
New Caledonian PineAraucaria columnaris (A. cookii)not rated, Central Valleyno Central Valley rating
Formosa Sugar PalmArenga englerinot rated, Central Valleyno Central Valley rating
NeemAzadirachta indicanot rated, Central Valleyno Central Valley rating
Bismarck PalmBismarckia nobilisnot rated, Central Valleyno Central Valley rating
American HornbeamCarpinus caroliniananot rated, Central Valleyno Central Valley rating
Japanese HornbeamCarpinus japonicanot rated, Central Valleyno Central Valley rating
American YellowwoodCladrastis kentukeanot rated, Central Valleyno Central Valley rating
Pagoda DogwoodCornus alternifolianot rated, Central Valleyno Central Valley rating
Giant DogwoodCornus controversanot rated, Central Valleyno Central Valley rating
Butterfly PalmDypsis lutescens (Areca)not rated, Central Valleyno Central Valley ratingTurn this into minutes on your water days
Every city page has a calculator that takes Autumn Splendor horse chestnut, 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 much water does Autumn Splendor horse chestnut need per day?
In July on the north-central coast, established Autumn Splendor horse chestnut needs about 4.1 gallons a day under a 10 foot canopy and about 16 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 Autumn Splendor horse chestnut change across California?
Yes. WUCOLS rates Autumn Splendor horse chestnut separately for each of the six California climate zones: moderate water in the North-Central Coastal zone, not evaluated in the Central Valley zone, not evaluated in the South Coastal zone, not evaluated 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 Autumn Splendor a buckeye or a horse chestnut?
It is sold under both names, and both groups belong to the genus Aesculus. Botanically it is a selection of Arnold buckeye, a hybrid that arose at the Arnold Arboretum in Massachusetts. Its flowers and husked nuts look much like a horse chestnut's.
Is Autumn Splendor poisonous?
Yes. It is listed as poisonous to people, dogs, cats and horses, from saponins that include aesculin. Symptoms include severe vomiting and diarrhea. Keep children and pets from chewing the leaves or the fallen nuts.
Why are the leaf edges on my buckeye turning brown?
This cultivar was chosen partly because it resists the summer leaf scorch common on buckeyes. When edges still brown, look for dry soil or salt buildup, since scorch comes from anything that limits water reaching the leaves. Deep, thorough soaks are the main remedy.
Does Autumn Splendor need full sun?
It grows in full sun or part shade. A tree in full sun dries its soil faster, so check under the mulch more often in an open spot. In part shade, check the soil before each soak, since it may still be damp.
How big does Autumn Splendor get?
Expect a rounded, low branched tree about 25 feet tall with a similar spread, though sources give a range of 15 to 35 feet. Give it room away from walks, since the branches sit low. The watered area should grow with the canopy.
Can Autumn Splendor grow in a lawn?
Yes, it is used as a lawn and street tree. Turf sprinklers wet only the upper few inches, which leaves its deeper roots short in dry spells. Give the tree its own slow soak and keep grass pulled back from the trunk.
More plant watering guides
Sources
- WUCOLS IV plant water use classification for Aesculus x arnoldiana 'Autumn Splendor', the University of California survey California agencies use for landscape plan reviewRead August 23, 2026 on wucols.ucdavis.edu
- Model Water Efficient Landscape Ordinance, adopted text and appendices, effective 2025-01-02 · monthly reference evapotranspiration per city, Appendix CRead August 23, 2026 on water.ca.gov/-/media/DWR-Website/Web-Pages/Programs/Water-Use-And-Efficiency/MWELO-Rulemaking/Final-MWELO-Text-and-Appendices_20250103.pdf
- UC Statewide IPM Program, irrigation scheduling using evapotranspirationRead September 30, 2026 on ipm.ucanr.edu/PMG/GARDEN/ENVIRON/evap.html
- Shaw and Pittenger, Landscape Irrigation System Evaluation and Management, UC Cooperative Extension, 2009Read September 30, 2026 on ucanr.edu/sites/default/files/2013-02/160836.pdf
- Pittenger, Water Management in Gardens and Landscapes, UC Riverside, 2017Read September 30, 2026 on ucanr.edu/sites/default/files/2017-03/258022.pdf