Illustration
Arnold Promise
Hamamelis × intermedia 'Arnold Promise'
Arnold Promise blooms from February through March.
Months here are Northern Hemisphere months; in the Southern Hemisphere, shift them by six months.
Growing Arnold Promise
Plant it in part sun. It prefers moderate water. It is hardy in USDA zones 5–8. Expect it to reach about 11 ft tall and 10 ft wide at maturity, in roughly 6 years (not yet checked).
No toxicity note is on file for Arnold Promise. That is not a clearance: check its safety for people and pets before planting.
What was checked
Mature height and spread, hardiness zones, sun and the trait tags were checked against named botanical sources for this plant. The bloom months and water need on this page were not, and each fact above says which. 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 Arnold Promise
Plant Arnold Promise 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 6, the middle of its hardy zones 5 to 8, spring means March to May and fall means August or September. Once settled, it blooms from February to March.
Month-by-month timing for your zone is on the planting calendar; if you garden near zone 6, the middle of this plant's hardy range, start with zone 6 in March. Derived from the plant's category, zones and bloom months plus typical zone frost dates, not checked separately.
How big does Arnold Promise get?
11 fttall5 ft 7 inan adult10 ftwideSee Arnold Promise 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 Arnold Promise
Derived from the mature spread above by a fixed rule, not checked separately: spacing is the spread, center to center.
Give Arnold Promise about 10 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 Arnold Promise 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
Arnold Promise's height, spread, hardiness zones, sun and trait tags were checked against 7 published sources on July 29, 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.
- Fine Gardeningplant guideheight, spread, hardiness zones, sun and trait tags
- Missouri Botanical Gardenheight, spread, hardiness zones, sun and trait tags
- Nature Hills Nurseryheight, spread, hardiness zones, sun and trait tags
- Clemson Home and Garden Information CenterClemson Cooperative Extension HGIChardiness zones, sun and trait tags
- Oregon State UniversityLandscape Plantshardiness zones, sun and trait tags
- brokenarrownursery.comBroken Arrow Nurseryhardiness zones and trait tags
- NC State ExtensionPlant Toolboxhardiness zones and sun
How the checking works, and what each standard covers, is on the verified plants page.
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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.