Perennial hibiscus put on quite the show

Rob Zimmer

One of my favorite flowering plants of the whole year is the incredible, show stopping hardy hibiscus, also known as rose mallow. Hybrids of native rose mallow found right here in Wisconsin, hardy hibiscus, believe it or not, are perennials here in this state.

Unlike tropical hibiscus, perennial hibiscus returns year after year, growing larger and larger, putting on a spectacular and flamboyant dance from the middle of July all the way through October.

Perennial hibiscus can grow quite large, reaching a height of 5-6 feet or more in three or four years. While they reach an incredible size and appear shrublike, perennial hibiscus technically are not woody plants. Growing on fresh, semi-soft, green stems or canes each year, these prolific bloomers can be cut to the ground each year following their flowering stage.

Each year, more and more varieties of hardy hibiscus are introduced to gardeners. Most of these bloom in shades of pink, red, white and fuchsia, sometimes swirled together like peppermint candy.

What gardeners love about these perennial beauties is the sheer size of the spectacular, papier-mâché blooms. In some varieties, these blooms may reach 8-10 inches across, with a dozen or more in bloom at the same time on peak days.

Nothing makes a statement in the late summer garden like hardy hibiscus in full, glorious bloom.

Hardy hibiscus are notoriously late to emerge in the spring. Often, we do not see signs of them until Memorial Day, or even after June 1. This is normal for these plants. Unfortunately, many gardeners who are out in their gardens working in April and May see no growth coming from the plant and incorrectly assume it’s dead. Then, they dig it up and toss it. Be patient with these giant floral beauties.

Once they begin to emerge in early June, they quickly grow — their canes rising dramatically and budding in the middle of July. By August and September, the show has begun.

In addition to their massive blooms, many people enjoy growing hardy hibiscus for their stunning foliage. Some varieties feature roundish leaves, others feature heavily forked or palmated leaves. The leaves may be bright green, variegated green and white, or rich, dark purple or maroon in color.

The combination of foliage and flowers make hardy hibiscus a choice perennial for your garden.

Check the plant tag closely on the varieties that you choose. Some hardy hibiscus grow well to Zone 5; others can be grown in Zone 4 gardens. All varieties should be protected in winter to ensure their survival and their return the following year. Simply covering them with leaves or mulch is all that is needed.

I often recommend gardeners allow their hardy hibiscus to remain standing all winter and wait until spring to cut it back. This is because of its late emergence during the spring season. By leaving the stems standing, you can see where the new growth will appear, even after the rest of the garden has flushed out.

Rob Zimmer is a nature and garden author, public speaker and radio show host on WHBY. Readers can find him on Facebook at