Illustration
Purple Emperor
Hylotelephium 'Purple Emperor'
Purple Emperor blooms from August through September.
Months here are Northern Hemisphere months; in the Southern Hemisphere, shift them by six months.
Growing Purple Emperor
Plant it in full sun. It prefers low water. It is hardy in USDA zones 3–9. Expect it to reach about 16 in tall and 20 in wide at maturity, in roughly 2 years (a house reading).
Pets
- Not yet checked for pets.
- Listed as poisonous to people by NC State Extension.
Lists differ and none is complete. If a pet eats a plant and seems unwell, call a veterinarian or a pet poison helpline.
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 Purple Emperor
Plant Purple Emperor 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 3 to 9, spring means March to May and fall means August or September. Once settled, it blooms from August to September.
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 Purple Emperor get?
16 intall5 ft 7 inan adult20 inwideSee Purple Emperor 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 Purple Emperor
Derived from the mature spread above by a fixed rule, not checked separately: spacing is the spread, center to center.
Space Purple Emperor about 20 in apart, center to center, so each plant has room to reach its full width.
Add Purple Emperor 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
Purple Emperor's height, spread, hardiness zones, sun, water, bloom months and color and trait tags were checked against 8 published sources on October 24, 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.
- Missouri Botanical Gardenheight, spread, hardiness zones, sun, water, bloom months and color and trait tags
- conservationgardenpark.jvwcd.govConservation Garden Parkheight, spread, hardiness zones, sun, water and bloom months and color
- Perennials.com (Heritage Perennials)Heritage Perennials (Valleybrook)height, spread, hardiness zones, sun and water
- nvknurseries.comNVK Nurseriesheight, spread, water and trait tags
- Plant Delights Nurseryheight, spread, hardiness zones and trait tags
- bethchatto.co.ukThe Beth Chatto Gardensheight, spread and sun
- RHSRoyal Horticultural Societyheight, sun and trait tags
- NC State Extensionsun
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.