The Year of the Coleus – Part II

Multiplying Coleus

Carol Ullerich, Master Gardener

Last week I introduced you to the beauty and versatility of coleus, an ornamental annual being promoted in 2015 by the National Garden Bureau.  This week I’ll share with you tips for propagating coleus—allowing you to save, or purchase, one plant and turn your initial investment into many plants. 

(Photo courtesy of National Garden Bureau)

From Seed

Begin sowing coleus seed 8-12 weeks from last frost date.  Coleus seed is small; mixing it with sand may promote more even distribution of the seed during sowing.  Sow in three inches of moistened growing medium—and cover the container—maintaining a constant 70 degrees.  Sow lightly as seed requires light to germinate.  Seedlings should appear in about two weeks.  As seedlings emerge, remove cover, but don’t allow potting medium to dry out.

From Cuttings

I collected and overwintered coleus that performed well in our trial beds at the UK Demonstration & Trial Garden in 2014.  I liked the varieties well enough to give them a chance to shine in my garden in 2015.  In February, I began propagating new plants from the “mother plants” I had saved.  I snipped several 2” lengths, (some sources recommend beginning with 4” – 6” lengths), removed the lowest set of leaves, lightly dipped the lower end in rooting hormone (including the now bare leaf nodes) and placed the segment in moistened potting soil (about 2” deep) inside a clear clamshell container.  I closed the container, creating a mini-greenhouse, and placed it in a sunny window with indirect light.  (If you don’t have clamshell containers, use a pot and place it inside a clear baggie or cover the pot with plastic wrap—the tops of the seedlings should not touch the top of the container or plastic wrap).  Roots should form in two to three weeks.

(Photos by Carol Ullerich)

After about six weeks, I’ll transplant the “babies” from the clamshell containers into individual pots.  TIPS:  While a 2” segment works well, more important than the length of the segment is that your cutting have at least two sets of leaves because you will remove the two bottom leaves and it is those nodes you’ll dip into the rooting hormone. 

(Photos by Carol Ullerich)

(Photos by Carol Ullerich)

Too much rooting hormone is not a good thing.  After dipping the segment’s end into the hormone, lightly tap the segment to remove any excess powder, leaving only a very light dusting on the segment.  (Rather than dipping directly into the jar of rooting hormone, put a small amount of powder into an empty pill bottle or film container into which you’ll dip your segments.  This keeps the hormone in the original container unadulterated).  Use a pencil to create several small planting holes in the moistened potting soil, otherwise you’ll knock off the hormone when you insert the segment into the clamshell container.  

Pinch the top out of your cutting to promote growth rather than flowering, leaving at least one set of leaves for photosynthesis. 

(Photo by Carol Ullerich)

Keep new cuttings moist (not wet) and maintain high humidity—you should see condensation on the lid of the closed clamshell container.  (The clamshell containers I use are recycled from take-out salads).  

In Water

Coleus may also be propagated by starting segments in water and then transferring them to potting soil once roots have formed.

Enjoy the beauty, durability and reliability of coleus this summer.  2015 is, after all, the Year of the Coleus!  And next fall, save some mother plants to get a head start on your 2016 garden.

2015 the Year of the Coleus!

(part 1)
Planning Your Garden 
Carol Ullerich, Master Gardener

Do you dream of coming home to an impressive swath of color like this?

(Photo provided by National Garden Bureau)

Perhaps you’d like to flank the entrance to your home with matching urns of these neon beauties?

(Photo provided by National Garden Bureau)

                                      

If I've struck a chord with you—or perhaps given you a theme for plantings along your driveway or sidewalk, you are in luck!  The National Garden Bureau has declared 2015 the Year of the Coleus!  While blossoms certainly catch the eye in any landscape, it’s foliage that creates the backdrop and allows those showy blooms to shine.  This year, make coleus your “go to” annual for colorful foliage, durability and a wide variety of leaf textures and plant shapes. 

Thought to have originated in Southeast Asia, Dutch botanist, Karl Ludwig Blume, is credited with naming and introducing coleus to England in the mid-19^th century.  Its square stems and opposite leaves confirm its place in the mint family and explain why this herbaceous perennial grows so consistently and reliably.

(Photo provided by National Garden Bureau)

Also known as flame nettle or painted nettle, over time coleus has fallen in and out of favor with gardeners.  Its heyday may have come during the Victorian era when coleus was used to create vivid, intricate bedding designs known as “carpet gardening” and even launched a frenzy among gardeners known as “coleus fever.” 

Since the 1980s, new coleus varieties have been introduced annually.  Hybridizers continue bringing new leaf shapes and color combos to market, but they are keenly aware of our desire for more sun tolerant varieties.  No longer reserved for shade-only gardens, in sunny areas, plant any of these coleus series:  Stained Glassworks; Wizard; Versa and Marquee; or any variety with the word “sun” in its name.  Coleus planted in direct sun will probably require more water, so be prepared to supplement with moisture.  As a rule, darker cultivars are more sun tolerant, while lighter-colored varieties appreciate morning sun and dappled afternoon shade.  Too much sun can result in leaf scorching; too little light results in weak stems, reduced vigor and less than desirable color.

                                        

(Photo provided by National Garden Bureau)

Most gardeners consider the dainty flowers produced by coleus to be insignificant and routinely pinch them out to promote bushier plants.  The most common colors found in coleus are green, pink, yellow, orange, red, dark maroon (almost black), brown, cream and white—with many shades of each.  Color patterns feature splashes, blotches, streaks, flecks, margins and veins.

There are three basic forms of coleus—upright, rounded or trailing.  Snip, pinch or trim plants every few weeks to prevent flower formation and promote bushier plants.  Pinch just above a set of leaves or branching junction for the best appearance (avoid leaving a stub).  Consider planting a trailing form as a groundcover or “living mulch” to add interest to beds, shade soil to retain moisture and suppress weeds.

In part shade/part sun areas, try these series:  ColorBlaze, Fairway, Superfine Rainbow, Main Street and Kong.  Coleus generally thrive so long as air temperature remains between 55 and 95 degrees F.  Plant once danger of frost passes, soil temperature is warm, and evening temperatures are above 60 degrees.  Strive for consistently moist soil, avoiding ground that is too wet or too dry.  Fertilize lightly every two weeks.
Part 2 next week.