Hibiscus 'Holy Grail' (Rose Mallow)
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Hibiscus 'Holy Grail' (Rose Mallow)

Rose Mallow 'Holy Grail', Hardy Hibiscus 'Holy Grail', Summerific Collection


Noted for its dark foliage and long blooming season, Hibiscus 'Holy Grail' (Rose Mallow) is a compact, well-branched, herbaceous perennial with extremely large, deep red flowers, up to 9 in. across (22 cm). The eye-catching blossoms open from abundant flower buds which cover the plant all the way up the stems, making it bloom for much longer than most Hibiscus. Blooming continuously from midsummer to fall, each flower lasts about one day and stands out against the incredibly near-black foliage of beautiful, oval-shaped leaves. As an added bonus, once the flowers are finished, their bright green calyxes starkly contrast with the dark foliage. Perfect backdrop or centerpiece for a sunny border. Great for containers too.

  • Typically grows up to 4-5 ft. tall and wide (120-150 cm).
  • Thrives in full sun in average, medium to wet soils. Tolerates some light shade but best flower production and disease resistance occur in full sun.
  • Prefers consistently moist, organically rich soils. Keeping this hibiscus watered will result in larger flowers and lush foliage. 
  • Site in locations protected from wind to minimize the risk of wind burn.
  • Plant in perennial borders for dramatic summer blooms. Great along streams or ponds, in bog gardens or in rain gardens.
  • Keep an eye out for blight, canker, rust, leaf spots, aphids, scale, whiteflies and Japanese beetle. Deer resistant.
  • Deadhead spent flowers to maintain a neat appearance.
  • Cut down in spring before new growth appears.
  • It is best to plant Hibiscus in the garden before the heat of the summer arrives, and should be heavily mulched the first winter.

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Requirements

Hardiness 4 – 9
Climate Zones 2, 2A, 2B, 3, 3A, 3B, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, H1
Plant Type Perennials
Plant Family Hibiscus
Exposure Full Sun
Season of Interest Summer (Mid,Late)
Fall
Height 4' – 5' (120cm – 150cm)
Spread 4' – 5' (120cm – 150cm)
Spacing 60" (150cm)
Water Needs Average, High
Maintenance Low
Soil Type Clay, Loam
Soil pH Acid, Alkaline, Neutral
Soil Drainage Moist but Well-Drained, Moisture Retentive
Characteristics Showy
Tolerance Deer, Wet Soil
Attracts Butterflies, Hummingbirds
Garden Uses Beds and Borders, Bog Gardens, Patio and Containers, Ponds and Streams, Rain Gardens
Garden Styles Informal and Cottage

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Photo courtesy of Walters Gardens Inc

While every effort has been made to describe these plants accurately, please keep in mind that height, bloom time, and color may differ in various climates. The description of these plants has been written based on numerous outside resources.


Requirements

Hardiness 4 – 9
Climate Zones 2, 2A, 2B, 3, 3A, 3B, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, H1
Plant Type Perennials
Plant Family Hibiscus
Exposure Full Sun
Season of Interest Summer (Mid,Late)
Fall
Height 4' – 5' (120cm – 150cm)
Spread 4' – 5' (120cm – 150cm)
Spacing 60" (150cm)
Water Needs Average, High
Maintenance Low
Soil Type Clay, Loam
Soil pH Acid, Alkaline, Neutral
Soil Drainage Moist but Well-Drained, Moisture Retentive
Characteristics Showy
Tolerance Deer, Wet Soil
Attracts Butterflies, Hummingbirds
Garden Uses Beds and Borders, Bog Gardens, Patio and Containers, Ponds and Streams, Rain Gardens
Garden Styles Informal and Cottage

Great Plant Combination Ideas with Hibiscus

Guides with Hibiscus

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