Illustration
Castle Rouge Blue Holly
Ilex × meserveae 'Hach 1'
Also called castle rouge holly and heckenblau
Castle Rouge Blue Holly blooms from April through May.
Months here are Northern Hemisphere months; in the Southern Hemisphere, shift them by six months.
Growing Castle Rouge Blue Holly
Plant it in full sun. It prefers moderate water. It is hardy in USDA zones 5–7. Expect it to reach about 6.5 ft tall and 4.5 ft wide at maturity, in roughly 10 years (a house reading).
Is Castle Rouge Blue Holly toxic to dogs or cats?
- Listed as toxic to dogs and cats by Pet Poison Helpline.
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
Mature height and spread, hardiness zones, sun, water, bloom months and color and the trait tags were checked against named botanical sources for this plant, with what the sources could not settle written down; years to mature size rests on a recorded house rule where no publisher states one, and is marked so; its common name and alternate names have not been checked yet. 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 Castle Rouge Blue Holly
Plant Castle Rouge Blue Holly 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 7, spring means March to May and fall means August or September. Once settled, it blooms from April to May.
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 Castle Rouge Blue Holly get?
6.5 fttall5 ft 7 inan adult4.5 ftwideSee Castle Rouge Blue Holly 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 Castle Rouge Blue Holly
Derived from the mature spread above by a fixed rule, not checked separately: spacing is the spread, center to center.
Space Castle Rouge Blue Holly about 4.5 ft apart, center to center, so each plant has room to reach its full width.
Add Castle Rouge Blue Holly 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
Castle Rouge Blue Holly's height, spread, hardiness zones, sun, water, bloom months and color, trait tags, soil, diseases, pests and toxicity were checked against 10 published sources on October 13, 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.
- Plant AddictsCastle Rouge Blue Holly, own product pageheight, spread, hardiness zones, sun, water, bloom months and color, trait tags and soil
- US plant patent (Google Patents)Google Patents HTMLheight, hardiness zones, bloom months and color, trait tags, diseases and toxicity
- Proven WinnersCastle Rouge, HACH1, PP25,475; one voice with Spring Meadowheight, spread, sun, bloom months and color and trait tags
- springmeadownursery.comSpring Meadow Nursery (Castle Rouge, HACH1, PP25,475)height, spread, hardiness zones, water and bloom months and color
- NC State ExtensionIlex x meserveae, speciessun, trait tags, diseases, pests and toxicity
- plantdatabase.uconn.eduUniversity of Connecticut Plant Database, Mark H. Brand (Ilex x meserv...sun, water and bloom months and color
- woodyplants.cals.cornell.eduCornell University Woody Plants Database (Ilex x meserveae, species)sun, water, soil and pests
- edepot.wur.nlP. Goossens, PCS Destelbergen, Belgium, Sortimentsmogelijkheden voor g...soil and pests
- hachmann.deHachmann Baumschulen (introducer, Heckenblau own product 2598)height
- pridescorner.comPrides Corner Farms (Castle Rouge, HACH1; documented Proven Winners re...height
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.