Shrub · Ranunculaceae
Clematis
Clematis
Plant it with sun on its head and shade on its feet, and clematis scrambles into a wall of bloom.
Full sun
Every 5–7 days
USDA 4–9
8–12 ft · 2.4–3.7 m
Overview
Clematis well deserves its old title, queen of the climbers. A member of the buttercup family, Ranunculaceae, it stretches from rugged wild species all the way to the large-flowered hybrids that drape a trellis or arbor in saucer-sized blooms. Across USDA zones 4 to 9 it comes back faithfully each year as a hardy perennial vine.
Bloom time runs on a long arc that shifts with the type. Plenty of clematis open in late spring to early summer, then swing back around for an encore in late summer to early fall. The plant climbs by curling its leaf stalks around slim supports, so reach for wires, netting, or a narrow frame it can grab rather than a solid post.
Patience pays off here far more than fussing. Sink it deep, keep the roots cool and moist while the top soaks up sun, and prune to suit its bloom group. Nail those few basics and a young vine digs in to deliver decades of bloom.
Care
The short version: sun on the top with cool, shaded, evenly moist roots underneath, rich well-drained soil, and pruning matched to the plant's bloom group.
Light
Clematis blooms hardest in full sun, ideally 6 or more hours a day, while it still takes partial sun or light shade. The old rule holds: head in the sun, feet in the shade, since hot, exposed roots shave off the flowers.
Water
Pour on at least 1 inch (2.5 cm) of water a week, more during dry spells, and never let the root zone cook. Mulch deep to lock that moisture in and keep the roots cool while the top stays in sun. Steady watering every 5 to 7 days keeps it pushing strong growth.
Soil
Set it into rich, fertile, well-drained loam, though clematis copes with clay or sandy ground once you amend it. It works across a wide pH range from 6.0 to 8.0, so most garden beds suit it after you dig in compost.
Temperature
Clematis is hardy stuff, shrugging off winters as low as -29°F (-34°C) and summers as warm as 95°F (35°C). That cold toughness lets it carry on as a perennial across zones 4 to 9.
Humidity
Everyday outdoor humidity does the job, so skip chasing a number. Air movement counts for far more, because still, packed-in growth opens the door to powdery mildew and stem rot.
Feeding
Work in a balanced fertilizer in spring as growth wakes up, then on through the season. Pause the feeding while it flowers, and keep nitrogen low, since it spurs the soft growth that wilt loves to invade.
Pruning
Prune by bloom group, because cutting the wrong type at the wrong moment costs you 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 get cut hard to 2 to 3 feet in late winter.
Repotting
Clematis seldom needs repotting and dislikes any disturbance to its roots. Move it only when roots circle or break out of the pot, when growth stalls, or when the soil dries out far too fast.
Size & spacing
A grown vine scrambles 8 to 12 feet (2.4 to 3.7 m) tall and fills out 2 to 6 feet (61 to 183 cm) wide. Hand it that space and a support to twine through so air can flow around the leaves.
When to plant
Set clematis out in spring or early fall, while the soil works easily and the weather stays mild. Plant it deep, with the crown an inch or two below the surface, and it gets its roots down 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
Most clematis problems land on the stems and leaves, from a shoot that drops overnight to a dusty film spreading over the foliage. Spot them early and you can cut the trouble out before it travels. Match what you see to the list below, then move while it still does some good.
One shoot caves in and darkens just as the buds break
When a single shoot folds and turns black overnight while the rest of the vine stays green, clematis wilt has moved in. This fungal stem rot tends to hit right as buds or flowers form. Scout low on the stem near the soil line for dark lesions. Prune every struck stem back to clean tissue or below ground, wipe your blades with disinfectant between cuts, and keep the water coming. Set with its crown a couple inches deep, the plant usually pushes fresh growth 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 in young shoots with telltale slime trails
Gnawed young shoots and torn holes on fresh-planted vines usually point to slugs and snails, given away by the silvery slime trails left behind. No trails? Step out after dark to check for earwigs wedged into the flowers and crevices. Ring young plants with iron phosphate bait, clear out debris and 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
Dusty white coating on leaves that curl and stay small
A chalky white layer across the top of the leaves, joined by stunted and twisted foliage, signals powdery mildew settling into stagnant, crowded air. Rub a leaf to sort it from ordinary dust: the film stays put and the leaf comes out misshapen. Pull the marked leaves, open up the vine for airflow, and steer water away from the foliage. A labeled fungicide early in the run reins it in when it starts to spread.
Fix:
- Remove affected leaves
- Improve airflow by thinning and proper spacing
- Avoid overhead watering
- Apply a labeled fungicide early in infection if needed
Tacky shoot tips packed with tiny soft bugs
Tight groups of soft green or dark bugs riding the shoot tips, plus sticky honeydew and perhaps sooty mold or ants, tell you aphids are working over the fresh growth. Flip a few young leaves to confirm them on the undersides. Blast a light run off with plain water, or hit them with insecticidal soap every 5 to 7 days for roughly 3 rounds. Hold a systemic insecticide in reserve for heavy, dug-in infestations.
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 no plant to eat, nor one to leave within easy reach of pets. Every part holds protoanemonin, an irritant that forms once the leaves or stems get chewed or crushed, and the ASPCA flags the vine as toxic to cats, dogs, and horses. That bitter taste stops most animals from eating much, but the sap can still sting skin and mouths, so give it careful handling.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds · People
Cats Mild
A cat that nibbles the leaves or stems can start drooling, vomiting, and running loose, with a raw, irritated mouth to match. That bitter, acrid taste tends to halt most cats before they swallow enough to cause real trouble.
Dogs Mild
Chewed foliage often leaves a dog drooling, gagging, and queasy with mouth irritation. The harsh taste keeps most from getting much down, which is why serious poisoning rarely happens.
Horses Mild
A horse that grazes the plant may salivate hard, turn off its feed, and end up with oral blistering and colicky discomfort. Given better forage nearby, horses usually steer clear of the bitter leaves.
Rabbits Caution
The same protoanemonin that bothers cats and dogs will sting a rabbit's mouth and gut, so call the vine off-limits and fence it well away from runs and hutches.
Livestock Caution
Cattle, goats, and sheep risk mouth and digestive irritation from browsing clematis, though the acrid taste turns most away unless pasture gets thin. Keep the vine well clear of grazing stock.
Birds Caution
The irritant sap makes clematis a bad neighbor for pet birds and poultry, so keep eager beaks off the foliage and stems.
People Caution
No part of this plant belongs on a plate, and the sap can redden and blister skin or sting the mouth on contact. Pull on gloves before you prune and wash up after, and keep small children from chewing the leaves.
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, yet a handful keep showing up in gardens. These are the names worth knowing, along with the bloom group each one lands in.
Jackmanii
A time-tested hybrid that opens large, deep velvety-purple flowers, it falls into Group 3, flowering on new wood and earning a hard cutback each late winter.
Nelly Moser
This Group 2 large-flowered hybrid unfurls pale pink petals, each striped with a darker carmine bar, and because strong sun washes those colors out it performs best with a little shade.
Henryi
A vigorous Group 2 large-flowered hybrid that throws big creamy-white flowers, sharpened by dark anthers at the center.
Sweet autumn clematis (Clematis terniflora)
Late in the season it blankets itself in small fragrant white flowers, yet it self-seeds with such force and has gone so invasive across parts of the eastern US that gardens are better off without it.
Clematis montana
An early, vigorous species that erupts in spring with masses of small flowers, this Group 1 type asks for only a light trim, and only once it wraps up flowering.
How to propagate
Clematis multiplies slowly, though it is not difficult, and the simplest routes clone a plant you already grow rather than starting from seed.
LayeringEasy
Spring to summer · A few months to a year
Layering is the surest way to turn one clematis into more. From spring through summer, pin a low, bendable stem down against the soil and let it root where it makes contact, then cut the new plant free once it grips on over the next few months to a year.
Stem cuttingsModerate
Late spring to early summer · Several weeks to months
From late spring into early summer, snip semi-ripe internodal cuttings off the current season's growth. They strike roots across several weeks to a few months, though they demand more attention than layering does.
DivisionModerate
Early spring · A season
In early spring, lift and split established crowns, going easy because clematis hates having its roots knocked about. Allow the divisions a full season to root in before they really take off.
Myths
Clematis is harmless to pets because it is just a flowering garden vine.
It belongs to the buttercup family and carries protoanemonin, an irritant the ASPCA lists as toxic to cats, dogs, and horses. A chewing animal can wind up drooling, vomiting, with diarrhea and a sore mouth. The bitter taste usually limits how much an animal eats, yet the vine is anything but harmless.
All clematis should be pruned hard every late winter.
Your pruning hinges entirely on the bloom group. Group 1 flowers on old wood and asks only for a light trim once it blooms, the Group 2 large-flowered hybrids get a light prune, and only the new-wood Group 3 takes a hard cutback. Cut an old-wood type to the ground and you remove that year's flowers.