Renowned as the “Queen of climbers,” clematis plants are a favorite of gardeners around the globe because of their vigorous vine growth and breathtaking floral displays. Once you add one of these stunning plants to your yard, you will try to figure out where you can plant another or even a few more.
Growing clematis plants is pretty straightforward, and they experience few pest problems. With a bit of care and regular pruning, you’ll be rewarded with a show-stopping plant filled with gorgeous blooms.
These gorgeous, long-lived perennials are grown worldwide, with species native to North America, Australia, India, China, Japan, and Europe. Different flower forms are available, but the standard flower is a large blossom containing six or seven petals. Flowers typically measure five to six inches across and range from white flowers to wine ride, deep purple to lavender, and even yellow.
Over two hundred different clematis species and hundreds of different cultivars are available. The different varieties allow you to choose plants in a range of mature heights, growth habits, flower forms, and blossom colors. Some plants grow as woody, deciduous vines, some grow as shrubs, and there are both herbaceous and evergreen types.
Popular cultivars include Comtesse de Bouchard, Jackmanii, General Sikorski, Henryi, Nelly Moser, Perle d’Azur, Rouge Cardinal, and Guernsey Cream.
Along with the different cultivars available, all clematis are classified into three pruning groups, based on when they flower and the type of wood they bloom on. Each group grows slightly differently, making it necessary to prune them differently to avoid cutting off the growth new buds develop on.
- Group 1 blooms in spring on old wood.
- Group 2 blooms in early spring on both old wood and new growth.
- Group 3 blooms in late summer or the early fall on new wood.
Most people skip starting their own plants and purchase young plants from a local nursery or garden center. Look for plants at least two years old, so you get blossoms quicker. Propagation via cuttings or divisions is possible, but they are finicky because the plants don’t like to be disturbed once their roots are growing.
People rarely try to start seeds as they are incredibly slow to germinate. According to the International Clematis Society (ICS), “Clematis seeds may take up to three years to germinate, but you should get some germination in about six months to a year.”
No matter how you start a plant, keep in mind that it can take several years to mature and flower vigorously.
The most successful way to propagate plants is to take softwood cutting in late spring. Take a four-inch cutting from a stem that is the current season’s growth. It needs to be healthy but not too soft or too woody. Remove the leaves, so there is only one on the cutting, and plant it in a container of compost.
Add a fine layer of sand or small pebbles to the top of the compost, and cover the pot with a see-through plastic bag or plastic wrap. Put in a warm spot out of direct sunlight, keeping the compost moist but not soggy. It can take cuttings up to five weeks to root. Once rooted, transplant outside.
If you have a strong, healthy plant, you can divide it in the spring. Start by removing the plant from the trellis or support, and cut back the stems, so they have no more than 3 or 4 buds. Dig up the mother plant, carefully divide the roots into sections, and replant the divisions in a similar spot.
Treat these new divisions like young plants, keeping them well-watered. Once they take off growing, it will be a season or two before you see strong growth and many blossoms.
You can plant a clematis in early fall or early to late spring, which is typical for many flowering perennials. They aren’t as picky about timing as trees or ornamental grasses. When planting, make sure to give the roots time to establish before the heat of summer or when plants go dormant in the late fall.
Plants prefer well-draining soil with a pH that is neutral to slightly alkaline. If your soil pH is too low, consider adding some limestone or wood ash to raise the pH slightly; when doing so, be very careful the pH doesn’t go too high. When digging a hole for planting your clematis, work some compost and granular fertilizer into the fill dirt.
When planting a young clematis, make sure you give it plenty of space to grow, including upward. Depending on the cultivar you are planting, your mature plant may grow very large depending on its growth habit. If you are planting more than one together, space them at least two to three feet apart.
Dig a planting hole roughly two to three times the width of the rootball and one and a half times deep. Remove your plant from the nursery container and set the clematis in the hole so the plant’s crown is about two to three inches below the soil surface. The first set of true leaves can be below the soil line.
Fill the hole, tamping the soil down with your hands or feet to eliminate air pockets. Once filled, water the soil well.
Most clematis varieties are recommended for growing in USDA zones 4-9. A few types are cold hardy to zone 3, and some are heat tolerant to zone 10. Plants need plenty of sunlight, moisture, and fertilizer for optimum growth. Regular pruning encourages plenty of blossoms and keeps them from looking leggy or scraggly.
Choose a spot in your yard or flowerbeds that receives at least six hours of fun sun daily. Plants thrive in full sun and develop more flower buds than those grown in partial shade. If you live somewhere hot, a spot that gets some afternoon shade is excellent. If you have partial shade, opt for Henryii or Nelly Moser varieties.
The first year or even two after planting, water your young plants regularly. Keep the soil slightly moist at all times without being waterlogged (which encourages clematis stem wilt). After plants are established, aim to give them about an inch (2.5cm) of water every week. During dry spells, water deeply to encourage better root growth.
When growing clematis, you need to fertilize often to support their heavy vegetative growth. In early spring, spread a shovelful of finished compost and a light dose of fertilizer around the plant. Then feed monthly with a balanced fertilizer during the early growing season until the plant begins to flower. Feeding your plant while it’s flowering can cause blooming to halt.
Correct pruning is one of the critical aspects of taking care of your clematis. To prune your plant correctly, you need to know how it flowers. Plants are divided into three different pruning categories, based on when they flower and if they bloom on new wood or old wood. These characteristics determine when and how to prune your plant.
- Group 1 doesn’t need pruning other than to shape them or remove dead vines.
- Group 2 should be pruned lightly in early spring after the buds develop so that you can see them.
- Group 3 can withstand hard pruning to keep them from getting leggy. Many homeowners cut them down to about twelve inches tall in late fall or early spring before new growth starts.
Clematis are born to climb, and they will grab onto anything to move upward and outward. They love to grow up a fence, an arbor, or trellises by wrapping their leaf stems or tendrils around an object. If they don’t have natural support to climb, construct a network of fishing line, twine, wire, dowels, or steel rods—anything under ½” diameter is perfect.
You may need to truss the vines as your plant starts to grow in the spring to prevent the vines from flopping over. Use twine or plant ties to fasten them gently to whatever support you are using. The vines break easily, whether woody or young, making it difficult to rescue a plant once it begins to fall.
Overall, plants are resistant to insect pests, but aphids, earwigs, scale, and whiteflies can be problematic. Slugs and snails also attack the tender new shoots and leaves. Watch for common diseases, including clematis wilt, powdery mildew, fungal spots, rust, and stem cankers. Plants also have good deer resistance, although deer will feed on almost anything when desperate.
- Mulch around the bottom of the plant to help keep the soil cool, keeping it a few inches away from the plant’s base. Clematis vines love cooler soil but plenty of warm, bright sunshine on their foliage.
- If you have a trellis for support, it may be helpful to make sure the top or upper part of the structure is anchored to your home (if up against the house). As the plant grows, it can become heavy and pull a trellis over if not secured.
- Plant two or more varieties next to one another for a changing display of flower styles and colors if you have space.
- To help keep the soil and underlying roots cool, you can also plant companion plants that shade the bottom of your clematis.
- To promote the second flush of blooms, deadhead spent flowers immediately after they fade.