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.
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| (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.
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| (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)
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| (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.
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| (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.
