Ornamental · Convolvulaceae
Cypress Vine
Ipomoea quamoclit
Hand it full sun and a string to climb, and cypress vine pays you back with feathery leaves and scarlet stars.
Full sun
Every 3–7 days
59–95°F · 15–35°C
65–90 days
Overview
Cypress vine is a quick-climbing annual in the morning-glory family, prized for its lacy, thread-fine foliage and small scarlet star-shaped flowers. The leaves are slit so finely they read almost as ferns, and the blooms pull in hummingbirds and butterflies from early summer right up to frost. Turn it loose on a support and it twines a full 6 to 20 feet (1.8 to 6 m) in one season.
Few vines are this forgiving to grow, which doubles as its draw and its drawback. Hand it a sunny corner and something to grab, and it climbs all on its own. It scatters seed freely too, so across warm regions it can settle in and pop up where you never sowed it.
The tough seed is the piece to mind. Those seeds pack LSA-type alkaloids and turn toxic to pets and people if swallowed, so place the vine and stash any saved seed beyond reach. Grow it for the spectacle, never for the pods.
Care
The short version: full sun, lean to average well-drained soil, and steady moisture as it takes hold. Hold the fertilizer, hand it a trellis or string to scale, and snip the seedpods if you'd rather it not sow itself across the whole bed.
Light
Cypress vine blooms hardest in full sun, which means 6 or more hours of direct light daily. It will still climb in part shade, but the flowers fall off quickly as the light fades.
Water
Keep the soil evenly moist while the vine settles in, then back off, since it brushes aside some drought once its roots take. Water deeply through dry spells instead of handing it frequent light sips.
Soil
Set it in average to poor, well-drained soil and skip the urge to feed it up. Rich ground or extra nitrogen drives leafy growth at the expense of flowers, so leaner wins here. It runs happily across a pH of 6.0 to 7.5.
Temperature
This is a heat chaser that thrives through the warm months and folds at frost. It grows across roughly 59°F to 95°F (15°C to 35°C) and stalls until the soil has warmed.
Humidity
Plain outdoor humidity suits it just fine, so there's no level to fuss over. Good airflow earns its keep far more than any number, keeping the fine foliage free of pests and mildew.
Feeding
Feeding usually backfires with this vine. It calls for almost none, and high-nitrogen feed hands you a curtain of leaves with scant flowers, so at most slip it a light low-nitrogen feed at planting in genuinely poor soil.
Pruning
Pinch the young tips to nudge the vine into branching, and trim stray stems to hold it where you want. As the season closes, clear out the spent vines and clip the seedpods to rein in its heavy self-sowing.
Repotting
none
Size & spacing
With support, the vine climbs 6 to 20 feet (1.8 to 6 m) tall and reaches 3 to 6 feet (91 to 183 cm) wide. Set up a strong trellis, fence, or string, since it blankets ground fast once the heat lands.
When to plant
Cypress vine is a warm-season annual with no patience for cold soil. Get the seed going indoors in late winter or sow it right outdoors once frost clears, and the vine flowers from early summer until the first fall frost takes it down.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: 6-8 weeks before the last spring frost; nick and soak the hard seed coat 12-24 hours before sowing.
- Plant: After the last frost when soil has warmed; can be direct-sown at the last frost date.
- Harvest: Early summer through fall frost.
Hardiness
USDA hardiness zones: 11–12
Temperature: down to 4°C
Troubleshooting
Cypress vine seldom causes headaches, and most of what crops up tracks back to overfeeding, too much shade, or a handful of usual pests on the fine leaves. Spot what you're seeing below, then chase the cause rather than the symptom.
Surprise seedlings cropping up everywhere come spring
Cypress vine is a prolific self-seeder that can turn weedy where winters stay warm, scattering seed that sprouts in sweeps the next year. Tug the volunteers out while they are tiny and slip free with ease. To stay one step ahead, snip the forming seedpods before they ripen and burst.
Fix:
- Pull volunteer seedlings while young
- Remove seedpods before they ripen and shed seed
All those leaves, yet hardly a single bloom
Fat, fertile ground and too much nitrogen steer a cypress vine toward leaves instead of buds, so it scrambles upward yet skips the flowers. Deep shade triggers the same letdown, because this vine wants a solid 6 hours of direct sun to bud up. Cut off the feeding, slide it into full sun, and let it run in lean, well-drained soil.
Fix:
- Stop nitrogen feeding
- Move or sow in a full-sun site (6+ hours direct sun)
- Grow in average to lean, well-drained soil
Speckled, twisted leaves trailing webbing or stickiness
Those threadlike leaves attract aphids, spider mites, and leaf miners, which dot and yellow the foliage, smear it with sticky residue, or etch pale winding tunnels. Turn a few leaves over and study the underside: soft clusters point to aphids, fine webbing flags mites, and squiggly trails mark miners. Beat them back early with a sharp water blast and insecticidal soap, then pull off any leaves tunneled past saving.
Fix:
- Rinse foliage with a strong spray of water to dislodge mites and aphids
- Apply insecticidal soap, treating early before populations expand
- Remove and destroy heavily mined or infested leaves
Toxicity
Skip this one anywhere pets or small children roam. The seeds contain LSA alkaloids and turn toxic if eaten, sparking stomach upset and, in bigger amounts, hallucinations and other nervous-system effects. The foliage rates a gentler caution, but the seedpods carry the real danger, so park them and every saved seed well beyond reach.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds · People
Cats Mild
A cat nibbling the leaves might drool or throw up. The seeds are the true threat, since they hold LSA alkaloids that can spark agitation, tremors, disorientation, or hallucinations once a cat swallows more than a couple.
Dogs Mild
Munched leaves tend to bring on vomiting and a spell of queasy stomach. A mouthful of seeds is the larger concern, because the alkaloids can set off restlessness, shaking, and an unsteady, disoriented dog.
Horses Caution
Horses seldom graze the wispy foliage, yet those same morning-glory seeds belong out of reach. A bite of seed could rattle the gut and, in volume, reach the nervous system.
Rabbits Caution
Rabbits should never browse this one. Treat the seedpods as the danger, because the alkaloid-loaded seeds can stir up digestive trouble and, in heftier doses, neurologic effects.
Livestock Caution
Grazing stock usually pass the vine by, though seed-laden plants in a pasture call for care. Eating the seeds can spark stomach upset and, in enough quantity, signs of nervous-system distress.
Birds Caution
Wild birds sip nectar from the flowers without trouble, yet the seeds are no treat to hand out. Keep harvested seed clear of pet birds, where even a little could spell problems.
People Caution
Nothing on this plant is raised for the table. The seeds are the catch: swallowing them can stir nausea and stomach pain, and a bigger dose of the LSA-type alkaloids can trigger hallucinations. Keep seeds and pods far from children.
Keep seeds and seedpods away from pets; the seeds are the main concern.
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
Cypress vine itself sets the scarlet-flowered benchmark, but a pair of close kin show up beside it and trip people up fast.
'Alba'
A white-blooming selection that trades the typical scarlet stars for crisp white ones.
Cardinal Climber (Ipomoea × multifida)
A cross of I. coccinea and cypress vine that shows wider, deeply lobed leaves and red trumpet flowers with pale throats, unlike cypress vine's threadlike foliage.
How to propagate
Cypress vine starts from seed alone, and the single trick worth mastering is loosening that stubborn seed coat before you sow.
SeedEasy
Sow indoors 6-8 weeks before last frost, or direct-sow after the last frost when soil is warm. · Germinates in about 1-3 weeks after scarifying; establishes and climbs quickly through the warm season.
Cypress vine springs from seed with hardly any effort, though that tough coat wants a head start. Nick or scarify each seed and soak it for 12 to 24 hours before sowing, then start it indoors 6 to 8 weeks ahead of your last frost or drop it straight into warm ground afterward. Seeds break dormancy in 1 to 3 weeks, and the vine races upward once the heat kicks in.
Myths
Cypress vine and cardinal climber are one and the same.
These are two separate vines. Cypress vine wears very fine, feathery, thread-like leaves slit nearly to the midrib, while cardinal climber, its hybrid child from a cross of I. coccinea and I. quamoclit, sports wider, deeply lobed palmate leaves. The foliage is the giveaway.