Ornamental · Convolvulaceae
Cypress Vine
Ipomoea quamoclit
Hand it full sun and a string to climb, and cypress vine returns the favor 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 annual in the morning-glory family that earns its place for lacy, thread-fine foliage and small scarlet, star-shaped flowers. The leaves read almost fern-like at a distance, and the blooms pull in hummingbirds and butterflies from early summer right up to frost. Set against a trellis, it climbs 6 to 20 feet (1.8 to 6 m) in one season, an easy way to dress a sunny wall.
It ranks among the simplest vines to grow, which is its appeal and its catch in equal measure. Hand it a bright corner and something to climb, and it carries on by itself. It also sheds seed freely, so in warm areas it can naturalize and reappear in spots you never planted.
The hard seed is what to keep an eye on. Those seeds hold LSA-type alkaloids and are toxic to pets and people if eaten, so position the vine and tuck any saved seed out of reach. Grow it for the display along a fence or seating area, not for the pods.
Care
The short version: a sunny spot, lean to average well-drained soil, and steady moisture as it gets established. Hold off on the fertilizer, set up a trellis or string for it to climb, and snip the seedpods unless you want it sowing itself across the garden.
Light
Cypress vine blooms best in full sun, which here means 6 or more hours of direct light each day. It will still climb in part shade, but the flowering tails off quickly as the light fades, so a south-facing fence suits it well.
Water
Keep the soil evenly moist while the vine settles in, then ease back, since it copes with some drought once it has rooted. Give it a deep soak through dry spells instead of frequent shallow sips.
Soil
Set it in average to poor, well-drained soil and skip the temptation to improve it. Rich ground or extra nitrogen feeds the leaves at the expense of the flowers, so leaner serves you better. It accepts a pH anywhere from 6.0 to 7.5.
Temperature
This is a heat lover that runs through the warm months and folds at frost. It grows across roughly 59°F to 95°F (15°C to 35°C) and waits for the soil to warm before it stirs.
Humidity
Everyday outdoor humidity is plenty, so there is no level to fuss over. Good airflow counts for more than any reading, keeping the fine foliage clear of pests and mildew.
Feeding
Feeding is mostly a misstep with this vine. It calls for almost none, and a high-nitrogen feed leaves you with a thicket of leaves and few flowers, so at the very most give a light low-nitrogen feed at planting in genuinely poor soil.
Pruning
Pinch the young tips to coax the vine into branching, and trim stray stems to keep it framing the space you intend. As the season closes, clear the spent vines and clip the seedpods to rein in its heavy self-sowing.
Repotting
none
Size & spacing
With support, the vine reaches 6 to 20 feet (1.8 to 6 m) tall and fills out 3 to 6 feet (91 to 183 cm) wide. Plan a solid trellis, fence, or string by a seating area, as it covers ground fast once the heat sets in.
When to plant
Cypress vine is a warm-season annual with no patience for cold soil. Begin the seed indoors in late winter or sow it outdoors once frost has cleared, and the vine carries color from early summer until the first autumn frost ends the season.
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 much fuss, and the few issues that surface usually come down to overfeeding, a too-shady spot, or a handful of common pests on the fine leaves. Find what matches below, then treat the cause rather than chasing the symptom.
New seedlings turning up all over the border
This vine is a prolific self-seeder that can drift into weediness in warm climates, scattering seed that returns in patches the next spring. Lift the volunteers while they are tiny and come away easily. The tidier move is to snip the forming seedpods before they ripen and let go of their seed.
Fix:
- Pull volunteer seedlings while young
- Remove seedpods before they ripen and shed seed
A green curtain that refuses to bloom
When the soil is rich or the plant gets too much nitrogen, your vine pours its energy into leaves and skips the flowers, climbing beautifully while the porch stays bare of color. Deep shade has the same effect, since the vine wants at least 6 hours of direct sun to perform. Stop feeding it, shift it to a brighter, sunnier spot, and let it settle into lean, well-drained ground.
Fix:
- Stop nitrogen feeding
- Move or sow in a full-sun site (6+ hours direct sun)
- Grow in average to lean, well-drained soil
Mottled, sticky leaves losing their look
The delicate foliage tends to attract aphids, spider mites, and leaf miners, which leave the leaves speckled and yellow, coated in sticky residue, or marked by pale meandering trails. Turn a few leaves over for a look: soft clustered bugs are aphids, fine webbing is mites, and squiggly lines are miners. Catch them early with a firm rinse of water and insecticidal soap, then pull off any leaves the miners have ruined.
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 is not a plant for spots within reach of pets or small children. The seeds contain LSA alkaloids and are toxic if eaten, bringing stomach upset and, in larger amounts, hallucinations and other nervous-system effects. The foliage is a gentler caution, but the seedpods are the true hazard, so keep them and any saved seed well clear.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds · People
Cats Mild
A cat picking at the leaves might drool or be sick. The seeds are the genuine threat, carrying LSA alkaloids that can bring on agitation, tremors, disorientation, or hallucinations once a cat takes in more than a couple.
Dogs Mild
A dog that chews the leaves tends to vomit and feel queasy for a while. The greater concern is a mouthful of seeds, where the alkaloids can spark restlessness, shaking, and an unsteady, disoriented animal.
Horses Caution
Horses seldom bother with the wispy foliage, but the morning-glory seeds belong well out of their reach. A serving of seed could disturb the gut and, in volume, reach the nervous system.
Rabbits Caution
Rabbits should not be browsing this at all. Regard the seedpods as the danger, as the alkaloid-laden seeds can upset digestion and, taken in larger amounts, cause neurologic effects.
Livestock Caution
Grazing stock generally pass the vine by, though seed-bearing plants standing in a pasture call for care. Swallowing the seeds can bring stomach upset and, with enough on board, signs of nervous-system distress.
Birds Caution
Wild birds sip nectar from the flowers and come to no harm, yet the seeds are no treat to hand out. Keep saved seed clear of pet birds, where even a little could cause trouble.
People Caution
Nothing on this plant is meant for the table. The seeds are the worry: eating them can bring nausea and stomach pain, and a heavier dose of the LSA-type alkaloids can set off 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 is the scarlet-flowered classic, though a couple of near relatives show up beside it and are simple to confuse.
'Alba'
A white-blooming selection that trades the familiar scarlet stars for crisp, pale ones.
Cardinal Climber (Ipomoea × multifida)
A cross between I. coccinea and cypress vine, showing wider, deeply lobed leaves and red trumpets with pale centers in place of cypress vine's threadlike foliage.
How to propagate
Cypress vine grows from seed alone, and the single trick worth learning is softening that tough 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.
Starting cypress vine from seed is about as low-effort as it gets, provided you soften that tough coat first. Nick or scarify each seed and let it soak for 12 to 24 hours before planting, then begin indoors 6 to 8 weeks ahead of your last frost or drop seed into warm ground once it passes. Sprouts show in 1 to 3 weeks, and the vine races upward as soon as the heat arrives.
Myths
Cypress vine and cardinal climber are the same plant.
These are two separate vines. Cypress vine wears very fine, feathery, thread-like leaves slit nearly to the midrib, while cardinal climber, its hybrid offspring from a cross of I. coccinea and I. quamoclit, shows wider, deeply lobed palmate leaves. The foliage is the giveaway.