Carol O’Meara – Colorado State University Extension
BOULDER COUNTY – Every so often a plant stops me in my tracks, either with beautiful foliage or gorgeous flowers. My spouse is used to me saying “wait a minute – stop, stop the car. Back up a little.” He’ll wait patiently as I crane my neck looking at the plant, getting out of the car if needed to get closer. If the curtains in the house twitch from the owner watching the crazy lady staring at their yard, I’ll wave and point at the plant in hopes that they come out to talk about it.
What captured my eye this summer is a gigantic beauty, the Hardy Hibiscus (Hibiscus moscheutos). The big, tropical flowers and colorful foliage are a double whammy that demand attention and make you dream of being in paradise.
Hardy hibiscuses are shrubs with an upright, mounding habit and dark green foliage. Some are large – up to five feet tall – while others stay small enough to fill large containers or center of the perennial bed. Once established, get ready for a show: they’ll sport huge, ruffled, crepe-paper like, seven-inch blooms which open wide to show off the anthers and stamen. Each stem can produce single or multiple flowers.
The plant will need staking and protection against high winds. Perennial hibiscus plants have no severe pest of disease problems.
Because the plant is big, plant it in a site where it can grow to four foot tall and three foot wide. Choose a location with full sun to part shade, and amend the soil with organic matter. Though they love heat, this isn’t a xeric plant, and does best in moist, organically-rich soils. Water it daily for two weeks to help it establish, then wean it back to irrigation levels that keep the soil moist but not soggy.
In fall, cut the plant back to a foot tall after the first frost – hibiscus blooms on new wood and this ensures a dazzling display every year. Mulch it with a four to five inch layer of wood chips to protect it from warming during winter. If it doesn’t pop up in early spring, don’t worry; the plant is slow to appear in the spring, nosing up after the soil warms to at least 70 degrees.
Once it appears in spring, prune off the remaining stems from last year and apply a time-released, balanced fertilizer.
Stop feeding after June to ensure that flower production is not impeded by the excess nitrogen.
Ready to choose your plant? You’ll find hardy hibiscus in deep reds, bright pinks, white with red throats, burgundy, blue, striped or solid. Plant a large with two smaller hibiscus to add drama to the planting.
Vegetable gardeners, don’t forget to come out to the Taste of Tomato event on Saturday, Aug. 27, 10 a.m. to 1 p.m. at Gateway Fun Park, 4800 N. 28th St. in Boulder. Sample tomatoes, mingle, and talk about the love apple in this homegrown event. Entry is free if you bring three tomatoes to share (ten cherry tomatoes), otherwise entry is $5 per adult, and children get in free.
For details, visit harlequinsgardens.com.
Colorado State University Extension, together with Boulder County Parks and Open Space, provides unbiased, research-based information about consumer and family issues, horticulture, natural resources, agriculture and 4-H youth development. For more information contact Extension at the Boulder County Fairgrounds, 9595 Nelson Rd., Box B, Longmont, 303.678.6238, or visit ext.colostate.edu/boulder.
By Carol O’Meara, Colorado State University Extension, Boulder County
