February 2002

Plectranthus: Coleus’ Cousin By Richard Schoellhorn

With all the well-deserved attention that coleus hybrids arereceiving for their landscape and interiorscape performance, it seems like a good time to take a look at some of the closer relatives of coleus that have the same strong characteristics and solid performance.

As with coleus, plectranthus are fast-crop annuals; salablealmost as soon as they are rooted and tolerant of a variety of productionconditions. As the primary interest is foliage, plants can remain in goodcondition on retail shelves for longer periods of time. Use plectranthus as youwould coleus, although since leaf colors aren’t as vivid, plectranthuswill sell best as accent crops, foliage filler and mixed container materials.With the flowering types of plectranthus, schedule to make the most of the seasonand use for color and as value-added hanging baskets. In spring 2000,plectranthus was one of the plants of focus at the University of Florida trialsand showcased at the annual May field day.

Plectranthus are like coleus and salvia, members of the mintfamily, with rapid growth, aromatic foliage and a variety of shapes and sizes.Like coleus, these plants will do well in the irrigated landscape, containergardens and indoor situations as long as light levels are high. In fact, manyof the best known plectranthus are for the indoor market. Most plectranthus areused for foliage interest and have insignificant flowers, with a few notableexceptions.

With all the interest in new crops, groups of plectranthusare coming onto the market with profuse and very attractive flowers and green,aromatic foliage. The flowering plectranthus group is predominantly from SouthAfrica, where they are used as bedding and flowering hedge material. While theflowering mechanism is still being worked out, they appear to flower best inlate summer as nights cool and day length begins to shorten, which in northFlorida, is around October first. Timing schedules for the floweringplectranthus are still a bit sketchy, but the industry should be able to get awinter/spring flowering crop and perhaps another in the late summer and fall.

Suggested Varieties

The best-known flowering form in our industry is ‘MonaLavender’ from Ball Floraplant. This plant has a great form forcontainers and hanging baskets. Mona forms a low mound, requires a pinch inproduction to get the best shape and flowers profusely fromall nodes. While Mona has deservedly the best recognition of the floweringtypes, there are many other notable varieties. Some other forms currently insouthern region trade include plectranthus ecklonii, which reaches a height of4-5 feet and flowers with a rich, blue-purple, 6-inch spike from all terminals,and plectranthus ecklonii ‘Erma’, a pink flowered form. Both plantsare annuals, even in north Florida, but add strong color to the fall landscape.They can tolerate full sun, but foliage is best when some protection fromstrong sun is provided. As a side note, the “fragrance” of thefoliage is probably a bit of an exaggeration; stench might be more accurate. Wenicknamed these plants “Smelly Dog Plant”, as the foliage odor waspretty close that of a wet dog. However, this name actually stimulated interestin the plant; it was one of the most popular plants in the Milton trials.

Foliage types of plectranthus vary a lot in growth habit andform but are predominantly colored in shades of green, gray-green to silver andwhite, the most common of these forms being plectranthus amboinicus —Cuban Oregano. While this is not a “true” oregano, the foliage ishighly aromatic, and the leaves are generally white edged with green centers.Growth habit for Cuban Oregano is loosely upright or mounding, reaching aheight of 24 inches in the landscape. This plant will sport back to a solidgreen form, so propagators need to keep an Á eye on stock plants as thegreen form is much more vigorous than the variegated form. Allan Armitage, andthe University of Georgia, released ‘Athens Gem’, a tri-colorvariegation that is quite nice. Try using Cuban Oregano in mixed containers forsturdy summer foliage color, as an annual in the landscape and pared with herbs(although few cooks use it twice…).

A close companion to Cuban Oregano is plectranthus forsteri’albo-marginatus’, Forster’s plectranthus. This is also agreen-white variegated form but with larger leaves, a more upright growth habitand a more refined look to the plant. Leaves are corrugated olive green with aclean white border. Plants rarely flower and have a better growth habit in thelandscape than Cuban oregano.

Plectranthus argentatus is a strong, upright, solid gray species. This is a horsylarge plant with matt silver foliage, similar to ‘Dusty Miller’,though not as bright a gray. The plant lends itself to landscape use verynicely in much the same way as Dusty Miller but with larger and faster growing.In mixed containers, this plant will take over if you don’t use vigorousplants in the mix with it.

For hanging basket culture, there are quite a fewplectranthus to choose from and all of these work equally well in mixedcontainers. Most of these plants flower sporadically in late summer, but theyhold onto their leaves, so flowering is a good thing in this case, unlikecoleus.

Plectranthus australis (verticillatus), Swedish Ivy, is anold standard houseplant and hanging basket plant that has literally beenhanging around for years — and for good reasons; it holds up well withthe average consumer’s care or lack thereof. Consider working this plantinto your hanging basket and mixed container schedules; it is fast, has glossygreen leaves, takes shade and always looks good. This is definitely one toavoid full hot sun, as the leaves will scorch.

Plectranthus oertendahlii, Creeping Coleus, and plectranthusfruticosus are two plectranthus with purple-toned foliage. In the industry,these two plants are often confused with one another and sold synonymously.However, P. oertendahlii is a smaller leaved plant with prominent silver veinson a purple-green leaf, and P. fruticosus has larger leaves and a more generalpurple tone overall. Both are strong hanging basket plants and add purple tonesto mixed containers.

Plectranthus madagascariensis, Variegated Mint Leaf, isanother old time plant making a come back because it takes bright light, growsfast and easy, and has an arching, creeping growth habit that works in bothbaskets and mixed containers. Green leaves reach up to 1 inch in diameter withclear white margins, and the plant will grow to 3 feet in diameter in a season.It is a strong performer in the southern landscape as well as in containers.Unlike many of the other plectranthus, which can be gangly without a pinch,this plant has a good, dense growth habit and looks good all the time.

The variety of textures, colors and forms available togrowers make plectranthus a crop we should all consider adding this spring.

Why Weeds?

In our industry, things are changing very quickly asfloriculture adjusts to becoming a commodity to the American consumer.It’s really only beginning — we have a long way to go. In my view,the future of the greenhouse business looks a lot like the history of theAmerican farmer, but nurseries have an advantage. We watched what happened tothe small farmer; we know what is needed to make the transition; and we haveexcellent examples of successful small farmers around us today. So as we facethe same forces shaping our industry, we can avoid a lot of the pitfalls thatthe small farmer faced.

This stuff has all been written before. Increasing marketpressures will force the formation of major nurseries; thesemega-nurseries’ sole purpose will be to supply the demand for flowers atthe retail level. As these large corporations grow, the small local nurseriesare going to need to change as well. Small nurseries are going to need todevelop specialized products and services that separate them from the mega-nursery.If they fail to do this, they will disappear because, to the consumer, theywill become invisible. Quality won’t be enough to save the small nursery;it wasn’t enough to save the small farmer. The average consumercan’t tell the difference between an average and a superiorproduct…unless you are there to tell them the difference.

Don’t get the wrong impression; the formation ofmega-nurseries isn’t evil; it is a fact of life for our industry, as isthe development of the big box garden center. This is our future, it is thecost of becoming something Americans feel is a necessary part of life. Imaginehow the corner market felt when the first supermarket came along —probably a bit like the smaller nursery feels today. The message is change; themedium is plant materials and services, and the whole thing is progress whetherit seems like it right now or not.

So why a column on a bunch of weird crops that have smallmarket share? Because they offer something different; they give smalleroperations an edge in the market, and honestly, because I love these plants.While all these giant operations are forming and learning how to control bigmarkets, there is a lot of money to be made by personalizing what you do. Ithink a conservative adoption of new crops is a good first step indifferentiating your nursery from your competition. It’s only a stepthough, because you’ll need to know how to use these plants, how topresent them differently and how to provide services that augment your originalcrops.

So this column is here to promote new crops. Not all of themwill work for you, but some will, and by carrying them as part of your cropmix, perhaps you’ll attract a few new customers. New crops are always acomplicating factor in nursery production. They cause problems; they sometimesfail; but every production nursery should develop a crop experiment program,because it keeps you thinking about change. Also, getting new crops out in thepress raises the awareness of our industry’s plant breeders.

This column will also promote the new markets that arealways coming along and offer ideas to nurserymen looking for niche markets. SoI hope you enjoy this concept column, and I’ll try to make somethingproductive out of my 15 minutes of fame by giving you some ideas — somereminders — that there’s always something new coming down thepipes. If there’s a group of plants you’d like to hear more about,please contact me, and I’ll work on getting some of the basics out toyou.