Ornamental Sweetpotatoes for the Home Landscape

Meri Reeber, NC State University
Ornamental Sweetpotatoes
for the Home Landscape
Ornamental sweetpotatoes (Ipomoea batatas: ih-po-mee΄-a ba-ta΄-tas) are extremely heattolerant, tropical, perennial vines grown as annuals in North Carolina. They look great covering annual beds, hanging over walls, or trailing from containers of all sizes. Ones with brightly
colored foliage can be used to form large swaths in the landscape. Those with more muted colors
look great as a backdrop to vibrant flowers. Good companions for ornamental sweetpotatoes
include calibrachoa, coleus, cordyline, dragon wing begonia, elephant ears, lantana, petunias,
spike dracaena, ornamental grasses, verbena, zinnia, and many other heat-tolerant annuals.
Ornamental sweetpotato leaves vary in shape
from cultivar to cultivar. They may be heartshaped, lobed like sycamore or maple leaves, or
deeply lobed like some Japanese maple leaves.
They are primarily foliage plants but will occasionally bloom in the landscape with pale lavender, morning-glory-like flowers. Most cultivars
can grow runners over 10 feet long, although
vines in the newly developed Sweet Caroline
series are more compact growers.
Keys to success with sweetpotato vine in the
landscape
1. The more sun they get the better.
2. Give them plenty of room. Some cultivars get quite large and need to be spaced
3 to 6 feet apart.
3. For containers, select cultivars that do
not produce large storage roots.
Photo courtesy Proven Winners
Photo courtesy Proven Winners
Sweet Caroline Light Green and Calibrachoa
Illusion Emerald Lace with Papyrus and
Diamond Frost
Ornamental Sweetpotatoes for the Home Landscape
Cultivars
Once there were only a handful of
cultivars available, but recent breeding efforts at NC State University
have more than doubled the number
of cultivars, expanding the ways
that sweetpotatoes can be used in
the landscape. The older varieties
tend to be vigorous growers that can
overwhelm a small bed or container.
They are great for large annual beds
and commercial sites, but they can
NC State Releases
Sweet Caroline Series
Cultivars: Bronze, Light Green, Raven, Red, and Green Yellow
Leaves: Moderately sized, threelobed, with the middle lobe much
longer
Growth: 2–4 feet
Habit: Mounding habit to slightly
trailing, depending on cultivar;
smaller root size; good choice for
containers
Disease Resistance: Nematodes
and fusarium
Sweet Caroline Sweetheart Series
Cultivars: Light Green, Purple, Red
Leaves: Heart-shaped
Growth: 2–4 feet
Habit: Mounding habit, more so
than the Sweet Caroline series
Disease Resistance: Nematodes
and fusarium
Sweet Caroline
Cultivars: Bewitched Improved
Leaves: Purple, uniquely shaped,
dentate edge
Growth: 1–2 feet
Habit: Bushy, compact, mounding
habit, smaller root size, good choice
for containers
Disease Resistance: Nematodes
and fusarium
Illusion Series
Cultivars: Emerald Lace, Garnet
Lace, Midnight Lace
Leaves: Moderately sized, deeply
lobed (fingerlike)
Growth: 2–4 feet
Habit: Mounding habit, excellent
choice for containers (Garnet Lace
has a slightly increased trailing
habit)
Disease Resistance: Nematodes
and fusarium
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produce large (basketball-sized) storage roots by the end of the season
that can push soil and plants out of
containers. The newer Sweet Caroline series releases are slower growing, more compact, and are ideal for
home gardeners and small to medium
containers. They do not form large
storage roots. There are many exciting cultivars under development in
NC State University’s sweetpotato
breeding program. In the future, look
for cultivars with finely divided or
lacelike leaves, a clumping (not vining) habit, and increased flowering.
How to select the plant
Meri Reeber, NC State University
Meri Reeber, NC State University
Ben Winslow, NC State University
Meri Reeber, NC State University
Select plants that are relatively compact, well colored, pest free, and
generally free of leaf damage. The
plants should fill out the pot but not
be overgrown. Leaves should be close
together on the stem. If plants were
grown in a shady greenhouse, the
color may not be fully developed,
but that will not affect the ultimate
landscape performance. You may
occasionally see a little leaf scalding
if the plant recently came from inside
a greenhouse. Neither of these things
will affect the plant in the landscape.
If you see any of the following indications of insect or disease problems,
however, don’t take the plants home,
as these problems could spread to
other plants in your landscape:
• Leaf stippling
• Fine webs
• Molds/fungi
• Sticky spots
• Many leaves missing
• Small white flies
• Small, green, soft-bodied
insects
• Small caterpillars
• Cottony substance in the joints
where the leaf joins the stem
Planting and soil preparation
Ornamental sweetpotatoes are not
cold tolerant and are grown as an
annual in North Carolina. Plant
them after the last frost date for your
Ornamental Sweetpotatoes for the Home Landscape
area. (See http://www.ces.ncsu.edu/
depts/hort/hil/hil-707.html for average last frost dates in North Carolina.) These plants grow best in the
heat and will not grow very quickly
until temperatures exceed 85°F. They
will grow well until the first hard
freeze, which will kill back the tops.
The roots may survive the first frost
but will not live through the winter.
If you are planting an entire bed
with them, space the vigorous varieties 3 to 6 feet apart, as they will fill
in the area quickly. Medium-size
plants should be spaced 2 to 4 feet
apart, and slow-growing or clumping
varieties should be placed 1 to 2
feet apart.
Sweetpotatoes grow well in a soil
amended with plenty of organic matter. They will not do as well in clay
soils or nutrient-poor soils. Monthly
applications of water-soluble fertilizer
will enhance growth.
Nutrition
Ornamental sweetpotatoes will do
best in fertile ground. Perform a
soil test and amend the garden as
recommended for vegetables.
Care throughout the growing
season
Ornamental sweetpotatoes are generally carefree plants. If they grow out
of bounds, you can prune them hard
and they will recover nicely. Irrigate
thoroughly and allow the plants to
Photo courtesy Proven Winners
Proven Winners Sweet Caroline
Bronze & Sweet Caroline Sweetheart
Light Green
dry down slightly between watering,
but avoid allowing the plants to wilt,
which can result in leaf loss. Also
avoid excess watering. A pH of 6.0 to
6.5 is best, but they will perform well
in a large range of soil pH levels. Ornamental sweetpotatoes perform best in
full sun. They can tolerate light shade,
but the colors may become less intense
and gain a green tinge.
Other Varieties
Cultivar: Margarita (Sometimes
labeled Marguerite, Margarite, or
Sulfur)
Leaves: Chartreuse, lobed
Growth: Will grow 8 feet or more in
one season
Habit: Very fast growing; forms large
storage roots late in the season
Disease Resistance: Susceptible to
fusarium and nematodes, although
healthy plants in the home landscape or containers are generally
not affected
Cultivar: Blackie
Leaves: Purple blush on dark green,
deeply lobed (fingerlike)
Growth: 8 feet or more
Habit: Very fast growing, very large
Disease Resistance: Susceptible to
fusarium and nematodes, although
healthy plants in the home landscape or containers are generally
not affected
Cultivar: Ace of Spades (a.k.a.
Black Heart)
Leaves: Purple, heart-shaped
Growth: 3–6 feet
Habit: Fast growing, large
Disease Resistance: Susceptible
to fusarium and nematodes, though
healthy plants in the home landscape or containers are generally
not affected
Cultivar: Tricolor (a.k.a. Pink Frost)
Leaves: Pink, green, and white variegated, three-lobed, smaller than
most (reversion to the straight green
leaf may occur; prune this portion off
to maintain variegation)
Growth: 1–2 feet
Habit: Small, slower growing
Disease Resistance: Fusarium and
nematodes
Ben Winslow, NC State University
Ben Winslow, NC State University
Ben Winslow, NC State University
Ben Winslow, NC State University
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Ornamental Sweetpotatoes for the Home Landscape
Insect Pests
Pest
Symptoms
Cucumber beetle
Management/Notes
Girdle stems, feeds on leaves,
stems, and fruit; larvae feed on
6 mm long, oblong-oval in shape, roots and tunnel through stems
beaded antennae, bright yellowgreen body. Spotted cucumber
beetle: 12 black spots on wings.
Striped cucumber beetle: 5 mm
long, pale yellow with 3 black
stripes.
Spread bacterial wilt disease as
well as mosaic virus.
• Cultural: Disturb soil to discourage egg laying, delay planting, seed heavily, cover plants,
select resistant varieties
• Chemical: Carbaryl, esfenvalerate, malathion
Flea beetle
• Cultural: Remove all leaf debris and weeds from the area.
Avoid placing plants near crucifers (e.g., cauliflower and broccoli). Install row covers. Time
plantings to avoid infestations.
Rotate crops.
• Biological:Bacillus thuringiensis var. san diego and var. tennebrionu
• Chemical: Carbaryl, cyfluthrin,
esfenvalerte, insecticidal soap,
malathion, permethin, spinosad
Small, circular holes or pits in
leaves
2.5–5.0 mm long, various colors;
enlarged hind legs allow them
Plant stunting (only if pests are
to jump considerable distances present in large numbers; this
when disturbed
can be particularly serious on
small plants)
Japanese beetle
Skeletonized leaves; large, irregular holes in leaves
1.27 cm long, shiny metallic
green body, bronze outer wings
Tortoise beetle
Leaves riddled with holes
Gold with black or red markings,
5–8 mm long, slightly flattened
and squared at the shoulders
Pests and Diseases
Pests and diseases are generally not
a problem in ornamental sweetpotatoes. In fact, they are even resistant to
grasshopper feeding.
Use integrated pest management
(IPM) strategies to manage potential
problems. IPM is based on using the
biology and behavior of plants and
their pests to effectively minimize
damage to plants, people, and the
environment. Begin with preventive
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Adult is visible in late spring and
early summer.
• Cultural: Keep plants healthy,
hand-pick beetles, cover rows
• Biological: Parasites, nematodes, fungi, Bacillus thuringiensis (Bt)
• Chemical: Esfenvalerte, permethrin
Not Effective: Traps frequently
attract more beetles than they
capture; milky spore treatment
Healthy plants are generally not
affected.
• Cultural: Adequate fertilizer,
good weed control, well-timed
planting
strategies and escalate through cultural, biological, and chemical options
as necessary.
• Preventive strategies include buying resistant varieties and keeping
them watered to prevent stress.
• Cultural strategies include modifying the planting area to make
it unattractive to pests by removing weeds or physically removing
pests.
Pictures
Susan Ellis
L. L. Berry
USDA/ARS
M. Shepare, G. R. Camer, &
P. A. C. Ooi.
• Biological strategies include welcoming insects that feed on the
pest, such as ladybird beetles and
lacewings.
• Chemical strategies include applying pesticides that may affect more
than just the target pest, so use
with caution. Read and follow the
product label.
Inspect plants regularly for
symptoms of damage, signs of pests,
Ornamental Sweetpotatoes for the Home Landscape
Animal Pests
Pest
Deer
Symptoms
Leaves eaten
Management/Notes
Pictures
• Cultural: Fencing, scare tactics
(must change regularly), shooting
• Biological: Predator urine (reapplied at regular intervals)
• Chemical: Repellents (reapplied at regular intervals)
Terry Spivey,
USDA Forest
Service
Rabbits
Leaves eaten
• Cultural: Fencing, removal of
habitat (brush piles, debris, and
other cover), trapping, shooting
• Chemical: Repellents
Alfred Viola,
North Eastern University
Vole
Plants girdled at the soil line,
damage below ground
(Meadow or Pine) 8.9 cm–12.7
cm
• Cultural: Mow to eliminate
habitat; till soil to eliminate burrows; trap
• Chemical: Rodenticide baits
Maja Jurc,
University of Ljubjana
and evidence of predators that may be
helping to keep populations in check.
Intervene early when problems appear.
The table above contains a list of the
most common problems.
Other pests that are rarely a problem in the landscape may become an
issue for sweetpotatoes grown as houseplants or in containers outside. Pests to
watch for include aphids, mealybugs,
mites, thrips, and whitefly. Manage
them as you would for other containergrown plants.
Are they edible?
The answer is yes, but you probably
will not like the taste. These plants are
the same species as the sweetpotatoes
grown for food, but they have been
bred for ornamental characteristics,
not culinary. They are likely to be
bland and mealy.
As an alternative to eating them,
try over-wintering them for replanting the next year. Dig them up in
the fall after the first hard frost and
store them in a cool place with some
slightly damp peat moss. If they do
not dry out over the winter, you can
replant them in the spring. Some cultivars, such as Margarita, will make
soccer-ball-sized sweetpotatoes under
ideal conditions. Other cultivars will
produce only small sweetpotatoes or
may not produce any at all.
Acknowledgments:
The authors wish to express appreciation to Benjamin Winslow, Meri
Reeber, Jarred Driscoll, Jo Cook, Mike
Munster, Barbara Fair, and Mark
Weathington for their assistance in
preparing this publication.
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Ornamental Sweetpotatoes for the Home Landscape
Diseases
Disease
Fusarium wilt
Fusarium oxysporum f.sp.
batatas
Symptoms
Leaves turn yellow and wilt or
may drop
Management/Notes
Pictures
More common in varieties grown
for food than in ornamentals
Cultural: Replace with cultivars
resistant to fusarium wilt
A soil-borne fungus that invades
roots
Charles Averre
Root-Knot Nematode
Meloidogyne incognita
Microscopic roundworm in the
soil
Stunted growth, leaf yellowing,
wilting during hottest part of the
day, galls on the roots; russetting, pimpling, and distortion of
roots
Cultural: Select resistant varieties that are certified as nematode free. Incorporate organic
matter. Rotate plantings with
oats, grass, or fallow land. Use
good cultural practices (mulching, watering, weeding, fertilizing) to minimize stress. Do NOT
move soil from an infected area
into a clean area. Discard seriously infected plants.
Biological: Grow a dense cover Jarred Driscoll,
NC State University
crop of African marigolds, Tagetes erecta, and till it into the soil.
Chemical: No chemical fumigants
or other pesticides are available.
Southern Blight
(Sclerotinium rolfsii)
Soft rot of the root, wilting and
death of leaves
Cultural: Purchase disease-free
plants of resistant varieties. Rotate planting to a different spot
each year. Allow 3-year gap between planting in the same spot.
Select well-drained site. Use
new soil in containers each year.
So far, this disease is limited to
large-scale industrial farming operations of food stock varieties.
Soil borne
Don Ferrin,
Louisiana State University
Common Problems and Disorders
Freeze Damage
Leaf damage, plant death
Sweetpotatoes are tropical
plants; freezing temperatures will
kill them.
Janice Kubo
Phosphorous Deficiency
Purple mottling on leaves
Continuous fertilization during
warm season will maintain optimum growth.
Brian Whipker,
NC State University
Magnesium Deficiency
Pale overall color; older leaves Sometimes seen in potted plants
are yellow but have green veins but rarely in plants grown in garden soil. Fertilize as needed.
Brian Whipker,
NC State University
6
NC STATE UNIVERSITY
Ornamental Sweetpotatoes for the Home Landscape
References:
Armitage, A. 2001. Armitage’s
Manual of Annuals, Biennials, and
Half-Hardy Perennials. Portland, OR:
Timber Press.
Bachman, G., W. Edgar. 2003.
“Ornamental Sweet Potato Response
to Bonzi and Sumagic.” SNA Research
Conference Vol. 48, Growth Regula-
tors Section.
Hamrick, D. (Ed.). 2003. Ball Redbook 17th Ed. Volume 2. Crop Production. Chicago: Ball Publishing.
Neal, J. 2006. “Bedding plant host
preference for dodder.” SNA Proceedings Vol. 51. Weed Control section.
Smith, T. 2007. Planning for
Spring: Production Guidelines for Four
Crops -- Osteospermum, Angelonia,
Calibrachoa & Ornamental Sweet
Potato (Ipomoea batatas). Amherst:
University of Massachusetts.
Zehnder, G. 1998. A Sweetpotato
Growers Guide to Insect Pest Management. Alabama Cooperative Extension document ANR-1104.
Prepared by
Dennis Carey, graduate student
Brian E. Whipker, Professor of Floriculture
Lucy K. Bradley, Extension Specialist, Urban Horticulture
Wayne G. Buhler, Professor and Extension Specialist
Department of Horticultural Science
North Carolina State University
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