Love them or hate them, hardy hibiscus can’t be ignored

There are some plants that elicit strong reactions, and you’ll know almost immediately if you love them or detest them. And hardy hibiscus is one of those plants.

Also known as swamp rose mallow (Hibiscus moscheutos), these large-flowered show-offs are either delightfully standout-ish or a bit garish, depending on your perspective, but there is no doubt that they are memorable.

Blooming in shades from white to red (with at least one purple variety on the horizon), the flowers can be up to 10 inches across. They masquerade as tropicals and look like something you’d see on a Hawaiian island, but they are actually native to eastern North America and are hardy to zone 5.

They are also the darlings of plant breeders, who for several years have been creating bold, new cultivars that are hybrids of several native species.

The newer varieties focus not only on flowers — bigger and more floriferous generally being the goal — but also on foliage, which has lead to several interesting dark-foliage varieties. Since they don’t generally bloom until the hottest part of summer, having interesting foliage is a boon.

One of the best dark-foliage varieties is ‘Dark Mystery,’ which sports reddish-chocolate colored leaves and icy white flowers with a cherry-colored throat. It was a top pick in a Chicago Botanic Garden evaluation.

There are several red varieties that sport the truest red you can probably find in a garden. Others, like ‘Heartthrob,’ skew toward burgundy.

If you’re really going for that tropical feel, ‘Evening Rose’ and Head Over Heels Adore, with corally pink and purplish pink flowers, respectively, look like they are just waiting to be tucked behind an ear.

These hibiscus grow to be quite large plants, over 5 feet tall and wide or bigger, and as much as they look like shrubs, they are true perennials that will die back to the ground in winter. And that may be the biggest challenge in growing them, because they are very late to emerge in spring, which can be frustrating to gardeners who are forced to play the “is it alive game” sometimes into June.

In addition to a sunny spot, they demand a good deal of moisture, as their swamp rose mallow common name would suggest. They can do well even in slightly boggy areas, but will be fine in a moderate moisture area as well. Just don’t try to grow them anywhere dry.

Unfortunately hibiscus are not without pest problems. Japanese beetles favor them almost as much as roses, and flea beetles and sawfly larvae can create unsightly holes in those pretty leaves. Usually the damage is tolerable, but bad infestations can nearly defoliate a plant.

And yet a spectacular flower show can make up for any pest-related unsightliness. The flowers last for just a day or two, but dozens of buds line up waiting for their turn to shine.

Hardy hibiscus won’t appeal to every gardener, but everyone will notice them when they put on an exuberant flower show.