California Buckeye or California Horse-chestnut is a species in the Sapindaceae family that is endemic to California, and the only buckeye native to the state. It is found over a large part of the state. It is a large shrub or small tree growing to 4-12 meters tall, with gray bark often coated with lichens or mosses. It typically is multi-trunked with a crown as broad as it is high. The leaves are dark green with five (rarely seven) leaflets, each leaflet 6-17 centimeters long, with a finely toothed margin and (particularly in spring) downy surfaces. The leaves are tender and prone to damage from both spring freezing or snow and summer heat and desiccation. It tends to drop its leaves readily. Caution should be exercised in using this plant in the garden because the fruits are toxic.
This plant is very drought tolerant, but looks better with some water. Native (white flowered) varieties seem to have lower water requirements. Tolerant of recycled water. To learn more, visit the Jepson Herbarium’s YouTube channel and watch a short video about this species: https://www.youtube.com/watch?v=uvYzsuUOaWc
Calscape website has more information: https://calscape.org/loc-California/Aesculus-californica-(California-Buckeye)?srchcr=sc603bc715acaa6
Sun: Full Sun, Part Shade
Moisture: Moderate – Low, Very Low
Summer Irrigation Max 2x / month once established
Ease of Care: Very Easy
Cold Tolerance: Tolerates cold to -5° F
Soil Drainage: Medium, Slow
Soil Description: Tolerates a variety of soils including clay. Tolerates Serpentine Soil. Soil PH: 4.0 – 8.0
Common uses: Hedges, Bank Stabilization, Deer Resistant, Butterfly Gardens
Companion Plants: Western Serviceberry (Amelanchier pallida or utahensis), Manzanita (Arctostaphylos sp.), Milkweed (Asclepias sp.), Spicebush (Calycanthus occidentalis), Ceanothus sp., Larkspur (Delphinium sp.), Buckwheat (Erogonum sp.), Coffeeberry (Frangula californica), White Pitchersage (Lepechinia calycina), Sticky Monkeyflower (Mimulus aurantiacus), Chokecherry (Prunus virginiana), Oak (Quercus sp.), Redberry (Rhamnus crocea), Currant (Ribes sp.), Hummingbird Sage (Salvia spathacea), Blue-eyed Grass (Sisyrinchium bellum), as well as numerous annual wildflowers. Sunset Zones: 3, 4, 5, 6, 7*, 8*, 9*, 10, 14*, 15*, 16*, 17*, 18*, 19*, 20*, 21*, 22*, 23*, 24*
Site Type: Dry slopes, canyons or stream edges, most often in the Coast Ranges or Sierra foothills.
Climate: Annual Precipitation: 5.8″ – 109.8″