Ornamental · Convolvulaceae
Cardinal Climber
Ipomoea × multifida
Set it in full sun and lean soil, and this fast vine sends up scarlet trumpets that draw hummingbirds through the whole summer.
Full sun
Every 3–7 days
50–95°F · 10–35°C
60–75 days
Overview
Cardinal climber is a fast twining annual that can clothe a trellis or fence within one season. A member of the morning-glory family, it arose from crossing cypress vine with red morning glory, a pairing that gave it deeply cut, palmate green leaves and small, brilliant red trumpet flowers. Those blooms pull hummingbirds in reliably.
Climbing vigorously, the vine reaches 6 to 15 feet (1.8 to 4.5 m) over a warm summer, so it needs something to grip from the moment it goes in. It behaves as a perennial only in the warmest zones; nearly everywhere else it is treated as an annual and sown fresh each spring once frost has passed.
Demands are minimal. Full sun and ordinary, well-drained soil cover its needs, and overdoing the care works against you, because rich conditions feed leaves instead of flowers. The one trait to keep an eye on is its tendency to self-seed, which can leave you with volunteers the next year.
Care
The short version: full sun, average to lean well-drained soil, and roughly an inch of water a week. Hold the fertilizer, supply a structure for it to climb, and pull off the green seed pods if you would rather it not spread.
Light
Give cardinal climber full sun to bring out the heaviest flowering. It will still grow in partial sun or light shade, but each hour of shade shifts the balance from blooms toward foliage, so a bright, open position repays the effort.
Water
Supply about 1 inch of water a week and hold the soil evenly moist while the vine is establishing. It tolerates brief dry spells once settled, yet steady moisture is what produces the fullest flowering.
Soil
Set it in average to lean, well-drained loam or sandy soil within the range of pH 6.0 to 8.0. Rich ground undercuts the display by driving lush vine and sparse flowers, so go easy on the compost.
Temperature
This is a warm-season vine that operates between 50°F and 95°F (10°C to 35°C). It needs warm soil to germinate and grow, and frost kills it outright, so there is nothing gained by planting it out too soon.
Humidity
Ordinary outdoor air meets its needs, with no humidity figure to chase. What counts is good airflow, which keeps the dense foliage from becoming a refuge for pests.
Feeding
Feeding is almost never required. In decent soil, skip fertilizer entirely, and in very poor ground apply only a light balanced feed, since high nitrogen yields leaves at the cost of flowers.
Pruning
Pinch out the young tips to push the vine into fuller branching, and train or trim it onto its support as it climbs. Cut away the green seed pods if you want to halt self-seeding.
Repotting
Grown as an annual, it completes one season and is not held over, so repotting in the usual sense does not apply. For a container, start fresh each spring in new soil rather than reusing a rootbound pot.
Size & spacing
Plan on a vine 6 to 15 feet (1.8 to 4.5 m) tall yet just 6 to 12 inches (15 to 30 cm) wide. Provide a tall, sturdy support and a little spacing so air can move freely through the foliage.
When to plant
Cardinal climber depends on warmth and has no frost tolerance at all, so timing follows soil temperature. Sow the seeds indoors a few weeks ahead of your last frost, transplant once the ground has warmed, and the vine will flower from summer through to the first frost.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: 4-6 weeks before last frost; nick and soak hard seeds first
- Plant: After last frost when soil is warm
- Harvest: Summer to frost
Hardiness
USDA hardiness zones: 10–12
Temperature: down to -1°C
Troubleshooting
Cardinal climber seldom causes much grief, and the problems that do arise concentrate in the flowers, the foliage, or in stray seedlings. Catch the early signals and you can correct course before it sulks or spreads. Find the match below, then act.
Speckled, ragged leaves with a tacky coating
Sap-suckers such as aphids and spider mites, along with chewers like Japanese beetles and leaf miners, all target this vine. Examine the leaf undersides and fresh growth to identify which one, then dislodge them with a hard spray of water or treat using insecticidal soap or horticultural oil. Pick the beetles off by hand and pull out any mined or heavily damaged leaves.
Fix:
- Spray off aphids and mites with a strong jet of water
- Apply insecticidal soap or horticultural oil
- Hand-pick Japanese beetles
- Remove and destroy mined or heavily infested leaves
All vine, no bloom
When the soil runs too rich or the vine sits in shade, growth shifts toward foliage and the flowers never form. Excess nitrogen drives that vegetative push at the expense of buds, so cut off the feeding and route the vine into full sun. Lean, well-drained ground paired with strong light restores the red trumpets.
Fix:
- Stop high-nitrogen feeding
- Move or train the vine into full sun
- Grow in leaner, well-drained soil
Last year's vine returning as seedlings
Left to its own devices, this vine self-seeds freely in warm climates, and the fallen seed germinates right where the parent stood. Remove the volunteers you have no use for. The durable solution is to cut the green seed pods off before they mature, dry, and release their seed.
Fix:
- Pull unwanted seedlings
- Remove developing seed pods before they mature and drop
Toxicity
Treat this as a toxic plant, with the hazard concentrated in the seeds. They contain indole alkaloids of the LSA type that can cause stomach upset and, in larger quantities, agitation and hallucinogenic effects in pets, livestock, and people. The foliage warrants only mild caution, but keep the seeds and seed pods well away from animals and children.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds · People
Cats Mild
A cat grazing on the leaves typically suffers little more than a queasy stomach and some vomiting. The seeds are where the alkaloids concentrate, so a mouthful of those can trigger agitation, tremors, and disorientation.
Dogs Mild
Chewed foliage usually brings on drooling and a round of vomiting. The seeds carry the real load, and a dog that eats them may grow restless, shaky, and visibly unwell.
Horses Mild
Horses are listed among the susceptible animals, and it is the seeds that hold the alkaloids upsetting the gut and, at higher doses, the nervous system. Keep grazing horses clear of the vine and its seed pods.
Rabbits Caution
The seed alkaloids that affect cats and dogs would land hard on a body this small, so regard the vine as unsafe browse for rabbits rather than acceptable forage.
Livestock Caution
Goats, sheep, and cattle that graze the seeds or seed pods can take in the LSA-type alkaloids, risking digestive and nervous-system trouble. Fence the vine away from pasture.
Birds Caution
Because the hazardous compounds sit in the seeds, keep poultry and pet birds from pecking the pods, even though the foliage poses far less of a concern.
People Caution
Nothing on this vine is grown for eating. The seeds contain indole alkaloids capable of causing stomach upset and hallucinogenic effects, which is reason enough to keep them well out of reach of children.
Keep seeds and seed pods away from pets and children; the seeds are the hazardous part.
Helpline numbers
United States
ASPCA Animal Poison Control: (888) 426-4435 (fee applies)
Poison Control: (800) 222-1222
Canada
Poison Centres: 1-844-764-7669
Varieties
Because cardinal climber is a hybrid, the names worth learning are those of its two parents. Both are common in gardens and account for the traits this vine inherited.
Ipomoea quamoclit (cypress vine)
One of the two parents behind the hybrid, carrying extremely fine thread-like leaves divided into needle-thin segments, giving it a far more fern-like look than the cardinal climber's own foliage.
Ipomoea coccinea (red morning glory)
The second parent, a red-flowered morning glory whose broad, heart-shaped leaves remain whole rather than finely dissected.
How to propagate
Cardinal climber raises easily from seed, which is the sole means of starting it. The one obstacle is working past its tough, water-resistant seed coat.
SeedEasy
Start indoors 4-6 weeks before last frost or sow outdoors after frost in warm soil · 5-10 days to germinate; weeks to begin climbing
Seed is the standard and only method for raising cardinal climber, started indoors 4 to 6 weeks before your last frost or sown outdoors once the soil has warmed. The seed coat is hard and water-resistant, so nick it and soak the seeds overnight first to achieve even germination. Expect seedlings to emerge in 5 to 10 days, with a few more weeks passing before they begin to climb.
Myths
Cardinal climber, cypress vine, and cardinal flower are all the same plant.
Cardinal climber is a hybrid between cypress vine and red morning glory, and its deeply lobed, palmate leaves fall in shape midway between the two parents. Cypress vine bears finer thread-like foliage, whereas red morning glory shows broad heart-shaped leaves. Cardinal flower (Lobelia cardinalis) is a separate plant altogether, an unrelated perennial in a different family rather than a climbing annual vine.