Clematis and other flowering vines play a special role in flower gardens. Since these plants grow up rather than out, they fill spaces that other plants can’t, and introduce a whole new dimension of color and texture.
In Britain, most flower gardens include one or more clematis vines. Here in the U.S, they are far less common. I think that’s because many people aren’t sure where to plant them. So here’s a quick primer about clematis: how they climb, what they like to climb on and the growing conditions they prefer.
How a Clematis Vine Climbs
Vines climb in a few different ways. Some have twining stems (like morning glory and pole beans), some have stem tendrils (grapes and peas). Others have aerial stem roots (climbing hydrangeas and English ivy) or specialized gripping pads (Boston ivy and Virginia creeper). There are also “scramblers”, which can’t really climb on their own, but can lie around and look pretty or be tied up onto a structure (climbing roses and bougainvillea).
Clematis use their leaves as tendrils. When the plant’s leaves are young, the leaf stems are supple and can wrap around things. Unlike stem tendrils, these leaf tendrils are relatively short, so they can only twine around something that’s less than about ¼”-inch in diameter. This is important when it comes to providing the right kind of support.
How to Support a Clematis Vine
Though there are some types of clematis that have a bushy growth habit, most of them are born to climb. As with other climbing plants, the growing end of the vine is on a mission, searching for something to grab onto. If the vine can’t find anything to attach itself to, it will stop growing and die back. So providing the right type of support helps the plant look good and grow well.
One of the simplest and most effective trellises for a clematis is a grid of coated or uncoated wire. The openings should be at least 2” in diameter – a smaller mesh size (like ½” hardware cloth) doesn’t work. I like using 14-gauge welded wire with a black or green poly coating and a 2” x 3” grid. It’s a bit stiff to work with, but is strong and long-lasting. A 4″ x 4″ grid also works fine.
Welded steel concrete reinforcing wire (sometimes called remesh) makes a great trellis for clematis and it will last for 10 years or more. The downside is you’ll need a pickup truck to transport the heavy rolls (or flat grids), bolt cutters to cut the wire, and lots of hand strength to bend it into place. But reinforcing wire is strong enough to be free-standing and that can open up lots of creative trellising options.
In some situations, a lighter wire mesh – still with at least 2” openings – works best. Because it’s more flexible, you can attach it to or wrap it around another structure. This is a good way to adapt a standard wooden trellis or wooden arbor so it’s clematis-friendly. You can also use this lighter weight wire to encircle a lamp post or mailbox post.
Where to Plant a Clematis
A happy clematis plant can live for 50 years or more, so take time to select a good planting spot. The plants have vigorous root systems and grow best in rich, loamy soil. The roots prefer cool soil and need consistent moisture. If possible, the top of the plant should be in full sun, though there are some varieties that will tolerate half-day sun (including Jackmanii, Nelly Moser and Henryi).
In Britain, clematis are often planted on free-standing, pyramidal trellises known as obelisks or tuteurs (see photo below). These are positioned within a perennial bed to add visual interest and show off the flowers. This type of support is also ideal for the plant because neighboring perennials keep the soil cool by shading the root zone. The top of the vine gets good air circulation and lots of sun, and that encourages good flower production. (Kinsman Company offers a nice selection of several different styles of tuteurs and obelisks.)
Here are a few places to consider planting clematis:
Against a wall (though not under an overhang where it won’t get any rain)
On a fence (attach wire mesh if needed)
Near a shrub or small tree (for easy support)
With another vine (such as a climbing rose)
Over an arbor or pergola (attach wire mesh if needed)
On a stone wall
On a free-standing trellis
Around a lamp post or mailbox
In a container
How to Choose a Clematis
When selecting a plant for your garden, you’ll want to think about a couple things, including the mature height, flower form, and color. If you have room for a vigorous vine that will grow 10 or 20 feet tall, there are dozens of cultivars to choose from. Breeders are also introducing more compact clematis varieties that still need support, but are ideal for small gardens and containers.
The standard clematis flower is a large, star-like blossom with 6 to 9 petals, measuring 5-6” across. Other cultivars feature smaller blossoms, double blossoms or lovely bell-like flowers. Flower colors range from white to wine red, lavender to deep purple. There are even yellow ones.
Another thing to think about when selecting a clematis is the bloom time. Some varieties flower in early summer and some bloom later. Reblooming clematis such as Multi-Blue and Blue Light, usually have a big show of flowers in early summer and then bloom again in late summer. If you have space, take a tip from British gardeners and plant two or more different varieties side by side. This will give you an ever-changing display of different flower styles, colors and bloom times.