When I first started working with plants, I learned a lot in a short amount of time.
I was selling plants and seed at a retail garden shop and customers would continuously educate me about what they were buying.
This would often result in productive, but sometimes awkward conversations.
During my first summer at the shop, a customer walked in and asked for “Althea.” I told her there was no one named ‘Althea’ that worked there.
Ultimate gardening fail.
I was swiftly ridiculed. The customer then informed me that she was looking for a hibiscus shrub and not an employee named Althea.
I ate a lot of crow that first season. I occasionally still do.
Bloom and grow
Twenty years later, though, I know more about hibiscus.
Summer is a high time for hibiscus, so I thought it a good opportunity to explore the species’ diversity, including my friend, “althea.”
Hibiscus plants are members of the mallow family, which also includes hollyhock, okra and cotton. There are three common types of flowering hibiscus that are grown in our area — rose-of-Sharon hibiscus, hardy hibiscus and tropical hibiscus.
There is also Confederate rose hibiscus, but it’s not common in our area, as it’s better adapted to coastal climate.
Hibiscus syriacus is a common landscape shrub, often referred to as rose-of-Sharon or Althea. Rose of Sharon is a Biblical reference, specific to the Book of Solomon and also an epithet for Christ. ‘Sharon’ translated from Hebrew means ‘plain’ in the geographical sense.
So a Rose of Sharon refers to the floral beauty of this specific region, at least in a botanical sense. How it trickled down to a widely-recognized name for Hibiscus syriacus, I couldn’t say. As for the nickname Althea, it seems to be traced to its definition as a dried root of marshmallow.
Hibiscus syriacus is an old-fashioned shrub or small tree, native to Asia. It was widely planted generations ago, and gradually fell out of favor as more flowering shrubs became available. There are now lots of new cultivars on the market, and it has become popular once again.
Althea’s growth habit is pretty consistent. It grows to approximately 10 feet tall and 8 feet wide.
It is a multi-stem shrub, but can be limbed up for a more formal, treelike appearance. Blooms are abundant, usually starting in June and lasting through the summer. Flowers range in color, including purple, lavender, white, pink and blue. Common cultivars include Minerva, Diane and Blue Bird. A few newer cultivars include purple and white pillar (columnar) and the chiffon series.
Hibiscus syriacus is notorious for reseeding, and has been placed on the invasive list in some states. Improved cultivars are often touted as sterile, though. Keep this in mind when shopping for Althea, as it keeps you from plucking seedlings at a later date.
Hibiscus moscheutos is also known as hardy hibiscus is considerably different than rose-of-sharon. This species has a wide range of common names as well, including mallow, rose mallow, marsh hibiscus and swamp hibiscus. According the NC State Extension, that list is even longer — including wild cotton, crimson-eyed rose mallow and swamp rose.
I grew up calling it mallow, which is what my grandmother called it. She grew a towering clump of crimson red moscheutos off the corner of her front porch, a place that stayed wet when the gutters would overflow. Hardy hibiscus and rose mallow seem to be the most common names I hear these days, though, despite the convoluted nomenclature.
Hardy hibiscus is an herbaceous perennial that thrives in wet areas. Native throughout the Eastern United States, it’s often found in or around swamps, wetlands, marshes, floodplains and riverbanks. It thrives in hot, full sun and has an upright, almost columnar habit.
The quintessential hardy hibiscus is a red variety called Lord Baltimore, which reaches 5 to 6 feet tall. Another common variety is Luna Red, which stays shorter, usually maxing out at 30 inches. Both have a striking red color with dinner-plate-sized blooms. As an ornamental accent plant, hardy hibiscus makes a bold statement in the summer garden.
Hardy hibiscus comes in a range of color. The Bethabara wetlands in Winston-Salem is home to an ivory native marsh hibiscus that is blooming now, all along the edges of the wetlands.
Hibiscus rosa-sinensis or tropical hibiscus is also widely grown in our area — albeit seasonally. Tropical hibiscus is what its name implies — tropical and not hardy for our winter climate. This species is also referred to as Chinese hibiscus, although it is most always just called tropical hibiscus.
Hardy in zones 9 to 11, tropical hibiscus grace our porches, patios and sun rooms with a swath of color during our warmest months. Better suited in the wild to tropical Asia and Hawaii, rosa-sinensis is a plant that demands sun and humidity. Tropical hibiscus make a great patio plant, and can bring an exotic vibe to an outdoor seating area.
Over the course of a season, tropical hibiscus can grow to around 5 feet tall, blooming continuously if kept happy. Potting mixture should be well-drained and consistent, and an even level of moisture is important. Maintaining humidity is also paramount, so misting and placing the potted plant on a bed of pebbles is often suggested.
Tropical hibiscus can be overwintered inside in two ways. If you have a warm sun room, they can overwinter with ease if you monitor the humidity level. To allow a tropical hibiscus to slip into a dormant stage, you can store it in a cool garage or basement, with minimal watering. They will shed leaves and generally pout until spring arrives.
So there you have it, a breakdown on the summer-loving hibiscus that grace our gardens.