Summerific® 'Holy Grail' Rose Mallow (Hibiscus hybrid)
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How Does Proven Winners® Measure Plant Sizes?
We list our plants by container size, which reflects the amount of soil and root growth each plant has when it ships. Actual plant height and width vary by variety and season, and many plants grow quickly as the weather warms.
To help you understand what to expect, refer to our size guide below. You can also find each plant’s approximate arrival size and mature size on its product page.
How Does Proven Winners® Measure Plant Sizes?
How Does Proven Winners® Measure Plant Sizes?
Plant Height By Container Size
This chart highlights the typical heights for each size category while also showing how container sizes compare, giving you a clear, straightforward way to understand plant size at arrival and choose the best fit for your gardening needs.
This chart shows typical plant heights and compares container sizes, helping you quickly understand arrival size and choose the best fit.
Soil Volume By Container Size
This chart shows the typical soil volume for each container size, listed in both imperial and metrics units for easy comparison.
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Introducing Summerific® 'Holy Grail' – a true garden treasure that combines stunning beauty with striking contrasts. This incredible plant boasts deep, near-black foliage with oval-shaped leaves that exude elegance and drama. The rich, deep red flowers, reaching an impressive 8-9" across, perfectly complement the dark leaves, creating a captivating visual harmony. As a bonus, once the blooms fade, the bright green calyxes stand out against the dark foliage, adding even more dimension and interest to your garden. A North American native, 'Holy Grail' brings massive, tropical-looking flowers to gardens as far north as zone 4. Though it emerges a little later in spring than other perennials, its fast-growing nature ensures it quickly establishes itself, with up to an inch of new growth a day. Perfect for areas with consistent moisture, use this striking hibiscus as a focal point to build your garden around and enjoy its beauty well into the fall.
- 48-54 inches tall and 54-60 inches wide at maturity
- Hardy in zones 4-9, be sure to check your USDA zone to ensure success
- Plant in part to full sun (4+ hours daily)
- Space plants 54-60 inches apart for best results
- Produces deep red flowers from midsummer to fall
- Maintains near black foliage from late spring to frost
- Great for borders, landscapes and focal point
- Attracts butterflies and bees while resisting deer
- Bog plant, fall interest, long blooming, native to North America
Care: Hibiscus love the sun and need moist, well-drained soil. Keeping these plants watered will result in larger flowers and lush foliage. Deadheading will improve the appearance of the plant, but is not necessary for continued bloom. It is best to plant Hibiscus in the garden before the heat of the summer arrives, and should be heavily mulched the first winter. In spring, cut back any remaining stems before new growth appears. Do not trim back in fall. A strong pair of loppers or a saw will be necessary to cut this plant back. Be advised that Hibiscus is always one of the last perennials to emerge in spring. Be patient, even if you think it is dead, it most likely isn't. Its vigorous growth rate more than makes up for this late start, however. Japanese beetles find these plants especially delicious. Fertilize with Proven Winners® Continuous Release Plant Food in spring and midsummer.
Shipping Info:
- Enjoy free shipping on orders over $175
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Size at shipping varies by season, plant, and trimming schedules
- Quart perennials are 5-8" tall at shipment
- 2 Gallon perennials are 18-28" tall at shipment