The coleus craze continues

What else can be said about coleus? They are a colorful addition to the garden, easy to grow and continue to become more commercially available in a wide range of colors and forms. Admittedly, I am addicted to this fascinating plant and have positive and memorable experiences with utilizing coleus in the public garden realm as well as my home garden. While I have little grower or retail sales experience with coleus, I view them as a self-important plant that does much of its own marketing on the bench with unparalleled vim and vigor. These plants almost sell themselves, and successful examples of coleus used in container arrangements, combinations and bedding schemes in shade all the way to full sun further extols the merit of this plant as indispensable for the gardening customer looking for success and pizzazz!

Coleus, also called “painted nettle,” is thought to originate in Southeast Asia. While there is some debate as to when it arrived in Europe, Dutch botanist Karl Ludwig Blume is credited with naming and introducing the plant in mid-19th-century England. This member of the mint family (Lamiaceae), featuring the traditional square stems and opposite leaves, comes in an astounding range of foliage colors, patterns, textures and forms. During my time in botanic gardens, proper nomenclature and labeling was important, and I recall coleus bouncing between the genera of Coleus, Plectranthus and Solenostemon over the years. For the sake of this article, I’ll simply refer to coleus, which is a name that has heft and recognition for new and experienced gardeners alike.

The primary ornamental feature of coleus is obviously the foliage, which can be represented by green, pink, yellow, orange, red, dark maroon (near black), brown, cream and white. The range of shades for these colors and the possible combinations is seemingly limitless. The intensity of coloration for the same variety in a sunnier location versus a shadier location can also be notably different. With some varieties of coleus, the underside of the leaf has a different color that contributes ornamentally as well (‘Henna’ is my favorite for this effect!). I’ve also taken to really examining the size and shape of the oppositely paired leaves, which might feature extreme indentations, very linear shape, scalloping, ruffles, etc. The edges of some varieties may also exhibit a different coloration that is noteworthy. While some gardeners will leave the small flowers, it’s recommended that you pinch these off and back to a leaf node to encourage more energy into stem and foliage growth. Coleus left to flower may lose vigor as the plant puts energy into seed production. I religiously pinch off flowers as they form.

When first exposed to mixed flats of seed-grown coleus over 35 years ago, the guidance I was given was to put them in shade and keep them watered. While they added some interest, I never felt they enjoyed the deep shade, and now I don’t even consider them a shade annual. Given decent soil, ample moisture (not wet feet) and some degree of sunlight, coleus should thrive. I like to fertilize my coleus every three weeks over the growing season and am not shy about pinching them back to control size.

Coleus do benefit from some degree of sunlight, and we’ve all now heard the term “sun coleus,” which truly opened up another realm of potential in the garden. Recent breeding for sun tolerance has brought so many wonderful coleus varieties out into our sunnier combinations. Breeding efforts and trialing further promotes bright, stable foliage coloration, superior vigor, more prolific branching, delayed flowering and some super cool forms (leaf shape and habit). I’m amazed by the scale and scope of coleus breeding at the University of Florida and have been equally entranced by a memorable visit with Chris Baker at Baker’s Acres (Alexandria, Ohio) to see his coleus creations. Clicking through the coleus offerings from Rosy Dawn Gardens (Michigan) is equally exciting. So many selections are available to the consumer, and well-grown and displayed coleus don’t linger overly long on the bench.

So many current varieties are fine in full sun (given ample moisture), while many of the classic seed series (Wizard, Fairway, Superfine Rainbow and Kong) can tolerate quite a bit of shade. Other seed series include Giant Exhibition, Premium Sun, Versa, Jazz and more. When I was at Rotary Botanical Gardens (Janesville, Wisconsin), we sourced seed for over 60 varieties of coleus still being offered and planted a fun and amazing collection.

While I’m not seeing as many flats and multi-pack offerings of coleus at local growers, the range of vegetative options that are available in 4-inch pots is astounding. The higher price point for larger, more established coleus in pots doesn’t seem to thwart brisk sales. Over the years, I’ve explored the wide range of vegetative offerings from series such as Stained Glassworks, Main Street, Under the Sea, ColorBlaze, FlameThrower and many more. There are also some trailing and semi-trailing forms that are excellent in the basket, trailing over container edges or as groundcovers. It’s important to convey mature size, habit, form and sunlight preferences for all coleus selections through proper labeling and interpretation, as these nuances may vary significantly between varieties.

Article brevity limits space for all my favorites, but I’ve been specifically entranced by the orange and red range of coleus that has exploded onto the scene with varieties that will get the size of small shrubs in the summer. Selections such as ‘Inferno’, ‘Campfire’, ‘Redhead’, ‘Ruby Slippers’ and ‘Beale Street’, to name a few, are vivid mounds of warm color that are excellent as accents or in groupings. They can dominate a smaller container but certainly can be nestled into larger groupings and combinations. I also adore chartreuse and golden selections like ‘Wasabi’, ‘Electric Lime’, ‘Wizard Golden’ and ‘Chartres Street’. I do like to give these varieties a bit of afternoon shade to minimize any leaf scorching. They add a palpable “glow” in any container or combination.

I can wax poetic about the hundreds of varieties of coleus that I’ve grown and observed, but suffice it to say, there is a coleus for everyone! The large, vivid varieties can be those “55 mph plants,” while the subtleties and nuances of leaf shape, color, texture and pattern for other varieties might be best appreciated from closer proximity in the container or nearby garden bed. In terms of customer interest and appeal, coleus have a strong future in the garden and will continue to flow from breeders to growers to retailers and through the checkout aisle to the gardener.

Mark Dwyer is currently the garden manager for the Edgerton Hospital Healing Garden in Wisconsin. For 21 years, he served as director of horticulture at Rotary Botanical Gardens in Janesville, Wisconsin. He also operates Landscape Prescriptions by MD, a landscape design and consultation business. mcdwyer@zoho.com