Shrub · Ranunculaceae
Clematis
Clematis
Keep its head in the sun and its feet in the shade, and clematis builds a climbing wall of bloom.
Full sun
Every 5–7 days
USDA 4–9
8–12 ft · 2.4–3.7 m
Overview
Clematis carries the old title of queen of the climbers honestly. It sits in the buttercup family, Ranunculaceae, and runs the gamut from tough wild species to the large-flowered hybrids whose saucer-sized blooms drape themselves across a trellis or arbor. Through USDA zones 4 to 9 it comes back each year as a hardy perennial vine.
Bloom time stretches out across the season depending on the type. Plenty of them open in late spring to early summer, then loop around for an encore in late summer to early fall. The vine climbs by curling its leaf stalks around anything narrow, so it needs wires, netting, or a slender frame to grip rather than a fat, solid post.
Clematis pays back patience more than fussing. Set it deep, hold its roots cool and damp while its top soaks up sun, and prune it to suit its bloom group. Manage those few things and a young vine digs in for decades of bloom.
Care
The short version: sun on the top and cool, shaded, evenly moist roots underneath, rich well-drained soil, and pruning chosen to fit the plant's bloom group.
Light
Clematis flowers hardest in full sun, 6 or more hours a day for choice, though it puts up with partial sun or light shade. The old saying still holds: head in the sun, feet in the shade, because hot, exposed roots cut down the bloom.
Water
Give clematis at least 1 inch (2.5 cm) of water a week, more during dry spells, and never let the root zone bake dry. Pile on mulch to lock in that moisture and keep the roots cool while the top stands in sun. A steady soak every 5 to 7 days keeps the vine pushing strong growth.
Soil
Set it in rich, fertile, well-drained loam, though clematis copes with clay or sandy ground once that soil is amended. It spans a broad pH range of 6.0 to 8.0, so most garden beds suit it after you work in some compost.
Temperature
Clematis is hardy stuff, weathering winters as cold as -29°F (-34°C) and summers as hot as 95°F (35°C). That deep cold tolerance is what lets it live on as a perennial across zones 4 to 9.
Humidity
Plain outdoor humidity suits it, so there is no figure to track. Air movement counts for much more, since stagnant, packed growth opens the door to powdery mildew and stem rot.
Feeding
Apply a balanced fertilizer in spring as growth wakes up, and on through the season. Pause while the vine is in flower, and go easy on nitrogen, which forces soft growth that wilt readily attacks.
Pruning
Prune by bloom group, since cutting the wrong type at the wrong moment costs you that year's flowers. Group 1 old-wood bloomers want only a light trim straight after flowering, Group 2 large-flowered hybrids take a light prune down to the topmost plump buds in late winter, and Group 3 new-wood types come back hard to 2 to 3 feet in late winter.
Repotting
Clematis seldom needs repotting and dislikes any disturbance to its roots. Shift it only if roots circle or push out of the pot, growth stalls out, or the soil drains far too fast.
Size & spacing
A grown vine climbs 8 to 12 feet (2.4 to 3.7 m) high and reaches 2 to 6 feet (61 to 183 cm) across. Hand it that space and a support to twine onto so air can flow freely around the leaves.
When to plant
Set clematis in the ground in spring or early fall, when the soil works easily and the weather sits mild. Plant it deep, with the crown an inch or two under the surface, and it roots in before heat or cold arrives. Look for the first flowers in late spring to early summer, often followed by a second flush later on.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Plant: spring or early fall
- Harvest: late spring to early summer, often reblooming in late summer to early fall
Hardiness
USDA hardiness zones: 4–9
Temperature: down to -34°C
Troubleshooting
Nearly all clematis trouble surfaces on the stems and leaves, whether it is a shoot that folds over in a night or a chalky film creeping across the foliage. Spot it early and you can cut the problem out before it travels. Match what you see to the cases below, then act while action still counts.
A green shoot suddenly droops and turns black at bud time
When a single shoot blackens and folds over right as its buds or flowers swell, while the rest of the vine stays green and upright, you are looking at clematis wilt, a fungal stem rot. Run your eye down low, near the soil line, where dark sunken lesions tend to show on the stem. Cut each ruined stem back to firm, healthy tissue or below ground, wipe your pruners with disinfectant between cuts, and keep the water coming. A vine set with its crown a couple inches deep usually pushes fresh shoots from below the next season.
Fix:
- Cut out and destroy all affected stems back to healthy tissue or below soil level
- Disinfect pruners between cuts
- Keep the plant watered; plants set with the crown a couple inches deep usually resprout from below ground the following season
Torn holes and chewed shoots on a young vine, marked by silvery trails
Tattered holes and gnawed young shoots on a freshly planted vine usually trace back to slugs and snails, which give themselves away with the silvery slime trails left across leaf and soil. With no trails in sight, go out after dark to look for earwigs wedged into the flowers and tight crevices. Ring young plants with iron phosphate bait, sweep away the debris and damp hiding spots, and set rolled cardboard to trap earwigs until the shoots toughen up.
Fix:
- Apply iron phosphate slug bait around young plants
- Remove hiding places and garden debris
- Trap earwigs with rolled cardboard or shallow traps
A chalky white dusting coats the leaves as they curl and shrink
A pale, powdery film spread across the top of the leaves, with the foliage shrunken, curled, and twisted out of shape, signals powdery mildew settling into still, crowded air. Rub a leaf to be sure: this coating sticks fast and the leaf underneath is warped, unlike loose dust that brushes clean. Pull off the worst leaves, open up the vine so air can pass through it, and keep the foliage dry. Reach for a labeled fungicide early on if the white film keeps creeping outward.
Fix:
- Remove affected leaves
- Improve airflow by thinning and proper spacing
- Avoid overhead watering
- Apply a labeled fungicide early in infection if needed
Tight clusters of soft little bugs cling to the sticky shoot tips
Soft-bodied insects in shades of green or near-black, packed onto the tender shoot tips and leaving a sticky honeydew that may draw sooty mold or ants, point straight to aphids draining the new growth. Turn the young leaves over to confirm the colonies underneath. A sharp blast of plain water knocks a light run off, or spray insecticidal soap every 5 to 7 days for about 3 rounds. Hold a systemic insecticide in reserve for the heavy, stubborn outbreaks.
Fix:
- Spray with insecticidal soap, repeating every 5 to 7 days for about 3 applications
- Hose off light infestations with water
- Use a systemic insecticide only for heavy, persistent infestations
Toxicity
Clematis is neither food nor a plant to leave within a pet's easy reach. Every part of it holds protoanemonin, an irritant that forms once the leaves or stems are chewed or crushed, and the ASPCA lists the vine as toxic to cats, dogs, and horses. The bitter taste turns most animals off before they eat much, yet the sap can still sting skin and mouths, so handle it carefully.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds · People
Cats Mild
A cat that chews the leaves or stems starts drooling, then vomiting, with diarrhea and a sore, irritated mouth. That bitter, acrid taste usually pulls it off the plant before it swallows enough to do real damage.
Dogs Mild
A dog gnawing the foliage usually drools and gags, then turns up with an unsettled stomach and an irritated mouth. The sharp flavor stops most from eating much, so serious poisoning rarely happens.
Horses Mild
A horse grazing the vine can end up salivating hard, going off its feed, with blistering inside the mouth and colicky cramping. Given other forage, horses tend to leave the bitter leaves alone.
Rabbits Caution
The protoanemonin that bothers cats and dogs irritates a rabbit's mouth and gut just the same, so treat the vine as off-limits and fence it away from runs and hutches.
Livestock Caution
Cattle, goats, and sheep can pick up mouth and gut irritation from browsing clematis, though the acrid taste turns most away unless the pasture thins out. Keep the vine well clear of grazing stock.
Birds Caution
The irritant sap makes clematis a bad neighbor to pet birds and poultry, so keep inquisitive beaks off the foliage and stems.
People Caution
Nothing on the plant is food, and the sap can redden and blister skin or sting the mouth where it touches. Pull on gloves before pruning and wash up afterward, and keep small children from putting the leaves in their mouths.
Sap can irritate skin; wear gloves when pruning and wash hands afterward.
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
Clematis numbers in the hundreds of species and cultivars, but a handful keep showing up in gardens. These are the names worth carrying around, along with the bloom group each one belongs to.
Jackmanii
The flowers on this classic hybrid open large and deep velvety-purple, and as a Group 3 type it blooms on new wood, so it takes a hard cutback every late winter.
Nelly Moser
This Group 2 large-flowered hybrid wears pale pink petals, each one striped down the center with a darker carmine bar; strong sun bleaches those tones, so it holds its color better with a little shade.
Henryi
A vigorous Group 2 large-flowered hybrid whose big creamy-white flowers are centered with a tuft of dark anthers.
Sweet autumn clematis (Clematis terniflora)
Late in the season it buries itself under small fragrant white flowers, but it throws so much seed and has spread so invasively through parts of the eastern US that it is not recommended for gardens.
Clematis montana
A vigorous early species that covers itself in masses of small flowers in spring; as a Group 1 type it takes only a light trim, and only once it has finished blooming.
How to propagate
Clematis multiplies slowly, though it is not difficult, and the simplest methods clone a vine you already own rather than starting from seed.
LayeringEasy
Spring to summer · A few months to a year
Layering is the surest way to raise more clematis. Bend a low, supple stem down to the soil any time from spring through summer, pin it where it lies, and let it strike roots at the contact point; cut the rooted youngster free once it holds on, somewhere over the next few months to a year.
Stem cuttingsModerate
Late spring to early summer · Several weeks to months
Through late spring into early summer, snip semi-ripe internodal cuttings from the current season's stems. Roots form across several weeks to a few months, though the whole process asks for more attention than layering does.
DivisionModerate
Early spring · A season
In early spring, dig up an established crown and split it, handling the roots gently since clematis dislikes heavy disturbance. Allow each division a full season to root in before it picks up steam.
Myths
Clematis is harmless to pets because it is just a flowering garden vine.
The vine belongs to the buttercup family and carries protoanemonin, an irritant the ASPCA lists as toxic to cats, dogs, and horses. Chewing it can set off drooling, vomiting, diarrhea, and a raw mouth. The bitter taste usually limits how much an animal eats, but that does not make the plant harmless.
All clematis should be pruned hard every late winter.
The right cut depends entirely on the bloom group. Group 1 flowers on old wood and only wants a light trim once it blooms, the Group 2 large-flowered hybrids get a light prune, and only the new-wood Group 3 is cut back hard. Cut an old-wood type to the ground and you remove that year's flowers.