Illustration
Mexican Buckeye
Ungnadia speciosa
Also called monilla
Also comes in purple.
Mexican Buckeye blooms from March through June.
Months here are Northern Hemisphere months; in the Southern Hemisphere, shift them by six months.
Growing Mexican Buckeye
Plant it in full sun. It prefers low water. It is hardy in USDA zones 7–9. Expect it to reach about 18 ft tall and 13 ft wide at maturity, in roughly 12 years (a house reading).
Pets
- Not yet checked for pets.
Lists differ and none is complete. If a pet eats a plant and seems unwell, call a veterinarian or a pet poison helpline.
No toxicity note is on file for Mexican Buckeye. That is not a clearance: check its safety for people and pets before planting.
What was checked
Nine facts were checked against named botanical sources, each recorded beside the sources that carried it: mature height and spread, hardiness zones, sun, water, bloom months and color, the trait tags, and years to mature size, which rests on a recorded house rule where no publisher states one and is marked so. Soil, diseases, pests, toxicity and the plant's own names have not yet been read for this plant, and its trait tags are the ones a feature uses rather than every word a page prints. Each fact above carries its own mark. The planting, spacing and size sections are derived from these checked facts by a fixed rule, not checked separately, and the plant type is the library's own classification.
When to plant Mexican Buckeye
Plant Mexican Buckeye in early spring as soon as the soil is workable, or in early fall at least six weeks before your first frost, so roots establish in cool weather. In zone 8, the middle of its hardy zones 7 to 9, spring means February to April and fall means September or October. Once settled, it blooms from March to June.
Month-by-month timing for your zone is on the planting calendar; if you garden near zone 8, the middle of this plant's hardy range, start with zone 8 in February. Derived from the plant's category, zones and bloom months plus typical zone frost dates, not checked separately.
How big does Mexican Buckeye get?
18 fttall5 ft 7 inan adult13 ftwideSee Mexican Buckeye in a garden plan: the planner shows it in 3D beside everything else you add, growing toward this size over the years.
How far apart to plant Mexican Buckeye
Derived from the mature spread above by a fixed rule, not checked separately: spacing is the spread, center to center.
Give Mexican Buckeye about 13 ft of clear ground in every direction, measured from its center. It is one plant with room around it, not a row, and a raised bed is too small for it.
Add Mexican Buckeye to a garden plan and the planner draws it at its full width, so you see the spacing before you buy.
Where these facts come from
Mexican Buckeye's height, spread, hardiness zones, sun, water, bloom months and color and trait tags were checked against 8 published sources on October 25, 2026. Each one is linked below with every fact it carried, which can include a fact this page still marks as not yet checked, because a source carrying a value is not the same as the value being held to the standard. Facts not in that list, and the planting, spacing and size sections, are not covered by these sources.
- tree-land.comTreeland Nurseryheight, spread, hardiness zones, water, bloom months and color and trait tags
- apps.cals.arizona.eduUniversity of Arizona Campus Arboretumheight, spread, sun, water and bloom months and color
- depts.ttu.eduTexas Tech Universityheight, hardiness zones, water, bloom months and color and trait tags
- Lady Bird Johnson Wildflower Centerheight, sun, water, bloom months and color and trait tags
- research.fs.usda.govUSDA Forest Service, Fire Effects Information Systemheight, sun, bloom months and color and trait tags
- spadefootnursery.comSpadefoot Nurseryheight, sun, water and bloom months and color
- plantlist.ose.nm.govNew Mexico Office of the State Engineerheight, spread and water
- texastreeplanting.tamu.eduTexas A&M Forest Servicewater and bloom months and color
How the checking works, and what each standard covers, is on the verified plants page.
Where it grows wild
Native to 2 states
United States: New Mexico, Texas
Recorded growing wild in 48 counties.
Also grows wild, but is not native, in Arkansas.
Range data from the World Checklist of Vascular Plants, Royal Botanic Gardens, Kew (CC BY 4.0, adapted) and USDA PLANTS. How the native range is credited.
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Design a garden with this
Drop this plant onto a 3D plan, see how it fills in, and watch your whole garden bloom across the year.