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GARDEN TOPICS
Coleus
Instead of colorful flowers, coleus
offers incredibly colorful foliage
in a variety of interesting shapes
and sizes. Coleus reached its first
peak of popularity during the
Victorian era, but fell into disfavor
when the greenhouse industry
began to produce it from seeds
instead of cuttings. While seedgrown coleus has it place in the
garden, the varieties produced
from cuttings offer better-behaved
plants.
Coleus is currently enjoying a
revival due to the appearance of
wonderful new varieties bred by
crossing the best of the old
Victorian varieties with their near
cousins from Asia and Africa. The
new varieties are often referred to
as Sun Coleus. So much has
changed about coleus that it is not
surprising that their botanical
name has changed too. We don't
know taxonomists were thinking
when they changed it to
Solenostemon scutellarioides, but
as long as coleus remains its
common name, we will all know
what we are talking about!
There are some advantages and
disadvantages to seed-grown
coleus varieties: They are
inexpensive and widely available.
They also offer consistency in size
and shape. Unfortunately, seedgrown varieties flower vigorously,
though not handsomely, and once
they flower, they tend to decline.
The new hybrids are more sun
tolerant and vigorous than their
Victorian ancestors. They also
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sport some incredible new color
combinations. Cutting-grown
coleuses are more varied in plant
habit, leaf form and size than their
seed grown brethren. Best of all,
they rarely flower. But they are
also more expensive than seed
coleus because the stock plants
need to be maintained disease and
insect free from one year to the
next.
The cutting coleus are seldom
tagged with their names, but are
almost always sold as individual
41/2-inch plants or large tubs and
baskets. If they are tagged, many
of them have wonderful names
like 'Duck's Foot', 'Pistachio
Nightmare', 'Inky Fingers', 'Flirtin'
Skirts', 'India Frills', 'Kiwi Fern'
and 'Dada Daddy'. Many of the
exciting new coleus have been
developed right here in Minnesota.
Coleus can be used for mass
plantings, backgrounds, accents
and fillers.
They will also act as color referees
for difficult combinations of
flowers. The most limiting factor
in using coleus is your
imagination. Coleuses planted in
containers and baskets make
outstanding displays; just be sure
to select varieties with habits that
match your needs. Some can get
very tall; others are more compact;
and others cascade over the pot.
You can find varieties that are
sturdily upright and will reach 2+
feet tall. Other varieties of coleus
will billow and trail at less than a
foot high.
In Minnesota, the new cutting
grown varieties will handle full
sun well unless we have a scorcher
of a summer. As a rule of thumb,
the red varieties are the most suntolerant.
Some of the new red varieties of
coleus have better color in the sun,
but most are just as brilliant in
high shade. Slugs may attack
coleus when the weather is wet.
Indoors they may have problems
with mealy bugs.
When you are transplanting a
coleus plant, ease it out of its
container, being careful not to
break up the root mass. With
properly prepared beds or
containers, about the only thing
that coleus demands is good
drainage. If you have a heavy clay
soil or your soil stays damp, grow
them in raised beds or containers.
In containers, use a loose peatbased potting mix
Before planting, work a general
purpose, slow-release fertilizer
such as Start-n-Grow or an
organic one like SustainTM into
the bed. Since coleuses are grown
for their foliage not their flowers,
use a water-soluble fertilizer
higher in nitrogen and lower in
phosphorus. acid formula is a
good choice. If you are using an
organic fertilizer, top-dress with
blood meal in mid-summer.
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Coleus propagates very easily from
stem cuttings. Take a three- to fourinch cutting from the tip of the stem,
remove any leaves that will be
beneath the soil and put the cuttings
in a clean pot of potting soil. Water
the cuttings well and enclose the pot
in a clear plastic bag to minimize
evaporation. Keep the cuttings in
high light, but out of direct sunlight.
In about two weeks the cuttings will
have rooted. Remove the bag and
grow them as a potted plant for the
winter, then plant them outside
when the temperatures warm in the
spring. Coleus will also root in a
glass of water; just take a cutting
and strip off the lower leaves. Place
the cutting in water and after about
three weeks roots will form. Once
rooted, transplant into soil.
Seed-grown coleus varieties need
shade in the afternoon and pinching
to prevent blooming. When you see
a flower head forming, just pinch it
off above the next set of leaves.
Coleus is relatively easy to start
from seed, though the seed is very
small. They germinate in 10-12 days
at 70o, so it's best to start them
indoors. Plant the seeds in midMarch. They germinate best with
light, so don't bury the seed; just
press them into the surface of the
soil.
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