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 fast-growing annual in the morning-glory family, loved for its lacy, thread-fine leaves and tiny scarlet star-shaped flowers. The foliage is sliced so finely it looks nearly fern-like, and the blooms pull in hummingbirds and butterflies from early summer right up to frost. Let it climb and it twines up to 6 to 20 feet (1.8 to 6 m) in one season.
It's one of the simplest vines to grow, which is both the fun part and the catch. Give it a sunny corner and something to grab, and it just goes. It also scatters seed freely, so in warm regions it can naturalize and pop up where you never planted it.
That tough seed is the thing to keep an eye on. The seeds hold LSA-type alkaloids and are toxic to pets and people if eaten, so place the vine and stash any collected seed out of reach. Grow it for the show, not for the pods.
Care
The short version: full sun, lean to average well-drained soil, and steady moisture while it's settling in. Hold off on fertilizer, hand it a trellis or string to climb, and snip the seedpods unless you want it seeding itself all over the place.
Light
Cypress vine blooms best in full sun, which means 6 or more hours of direct light each day. Sure, it'll climb in part shade, but the flowering thins out quickly as the light fades.
Water
Keep the soil evenly moist while the vine settles in, then back off, since it handles a bit of drought once its roots are down. Water deeply during dry spells instead of dribbling on frequent light drinks.
Soil
Set it in average to poor, well-drained soil and skip the urge to feed the ground. Rich dirt or extra nitrogen pushes leafy growth and cheats you out of flowers, so leaner really is better here. It's happy with a pH anywhere from 6.0 to 7.5.
Temperature
This is a heat lover that runs all through the warm months and gives up at frost. It grows across roughly 59°F to 95°F (15°C to 35°C) and won't really start until the soil has warmed up.
Humidity
Plain outdoor humidity works just fine, so there's nothing to fuss over. Good airflow matters far more than any number, keeping that fine foliage free of pests and mildew.
Feeding
Honestly, feeding is usually a mistake with this vine. It needs almost none, and high-nitrogen feed leaves you with a wall of foliage and few flowers, so at most give a light low-nitrogen feed at planting if the soil is truly poor.
Pruning
Pinch the young tips to nudge the vine into branching, and trim any stray stems to keep it where you'd like. When the season winds down, clear out the spent vines and clip the seedpods to rein in its heavy self-sowing.
Repotting
none
Size & spacing
With something to climb, the vine reaches 6 to 20 feet (1.8 to 6 m) tall and spreads 3 to 6 feet (91 to 183 cm) wide. Plan on a solid trellis, fence, or string, since it covers ground in a hurry once the heat shows up.
When to plant
Cypress vine is a warm-season annual that can't stand cold soil. Start the seed indoors in late winter or sow it right outside once frost is done, and the vine flowers from early summer until that first fall frost finishes it off.
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 rarely causes much grief, and most issues come down to overfeeding, too much shade, or a few familiar pests on those fine leaves. Find what matches below, then go after the cause instead of just the symptom.
Surprise seedlings turning up everywhere next spring
Cypress vine is a champion self-seeder that can go weedy in warm spots, scattering seed that comes up in patches the next year. Want to stay on top of it? Tug the volunteers out while they're tiny and easy to pull, and snip the forming seedpods before they ripen and drop.
Fix:
- Pull volunteer seedlings while young
- Remove seedpods before they ripen and shed seed
Lots of green, hardly any blooms
When the ground is too rich and there's too much nitrogen, your cypress vine pours its energy into leaves instead of buds, so it climbs like crazy and barely flowers. Heavy shade does the same thing, because the vine wants at least 6 hours of direct sun to bloom well. So stop feeding it, shift it into full sun, and let it sit 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
Spotted, warped leaves with webbing or a sticky film
That fine, lacy foliage tends to attract aphids, spider mites, and leaf miners, which speckle and yellow the leaves, leave a sticky film, or cut pale winding trails. Just turn a few leaves over and peek underneath: soft clustered bugs are aphids, fine webbing is mites, and squiggly lines are miners. Catch them early with a firm water rinse and insecticidal soap, then pull off any leaves that are badly tunneled.
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
This isn't a plant you want growing where pets or little kids can reach it. The seeds contain LSA alkaloids and are toxic if eaten, causing stomach upset and, in bigger amounts, hallucinations and other nervous-system effects. The leaves are a milder worry, but the seedpods are the real danger, so keep them and any saved seed well out of reach.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds · People
Cats Mild
A cat that chews on the leaves might drool or throw up. The bigger problem is the seeds, which hold LSA alkaloids and can cause agitation, tremors, disorientation, or even hallucinations if your cat eats more than a couple.
Dogs Mild
Nibbled leaves typically lead to vomiting and an upset stomach for a while. Swallowing a bunch of seeds is the real concern, because the alkaloids can set off restlessness, shaking, and a wobbly, confused dog.
Horses Caution
Horses don't often graze on the wispy foliage, but it's smart to keep those morning-glory seeds out of reach anyway. A mouthful of seed could upset the gut and, in larger amounts, hit the nervous system.
Rabbits Caution
Rabbits shouldn't be munching this one. Think of the seedpods as the danger, since the alkaloid-rich seeds can cause digestive upset and, in bigger amounts, neurologic effects.
Livestock Caution
Grazing animals usually steer clear of the vine, but seed-bearing plants in a pasture are worth watching. Eating the seeds can bring on stomach upset and, with enough of them, signs of nervous-system trouble.
Birds Caution
Wild birds happily sip nectar from the flowers without any harm, but the seeds aren't safe to hand out. Keep saved seed away from pet birds, where even a little could cause trouble.
People Caution
No part of this plant is meant for eating. The seeds are what to watch: swallowing them can cause nausea and stomach pain, and a bigger dose of the LSA-type alkaloids can bring on hallucinations. Keep seeds and pods well out of kids' reach.
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 is the scarlet-flowered classic, but a couple of close cousins show up next to it and are easy to confuse.
'Alba'
A white-blooming version that trades the typical scarlet stars for crisp white ones instead.
Cardinal Climber (Ipomoea × multifida)
A cross between I. coccinea and cypress vine, sporting wider, deeply lobed leaves and red trumpet blooms with pale throats, unlike cypress vine's threadlike foliage.
How to propagate
Cypress vine only comes from seed, and the single trick worth learning is softening that hard seed coat before you plant.
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 grows from seed with hardly any effort, but that tough coat needs a hand first. Nick or scarify each seed and soak it for 12 to 24 hours before planting, then start it indoors 6 to 8 weeks before your last frost or pop it straight into warm ground after frost passes. The seed comes up in 1 to 3 weeks and the vine takes off once the heat kicks in.
Myths
Cypress vine and cardinal climber are just the same plant.
Nope, they're two separate vines. Cypress vine has super fine, feathery, thread-like leaves slit nearly to the midrib, while cardinal climber, the hybrid that came from crossing I. coccinea and I. quamoclit, shows off wider, deeply lobed palmate leaves. The leaves tell you which is which.