Plant undemanding clematis and enjoy the show

Clematis are simple to grow; they are available in a broad range of colors, forms and sizes; and they boast one of the longest periods of bloom of any garden perennial.

They are also among the least demanding plants. Choose the correct site, plant in soil amended with organic matter, do some springtime pruning depending on which variety you choose, and clematis will bloom happily in your landscape for years.

Site Selection

As the old garden saying goes, “Clematis likes their heads in the sun and their feet in the shade.” While these conditions result in the most bountiful flower display, many clematis varieties are tolerant of lightly shaded conditions.

Clematis prefer to spread their roots through cool and evenly moist but well-drained soil. These conditions are easily created by covering the soil with a thick layer of mulch or by planting other perennials to shade its root mass.

Vigorous clematis varieties can be trained to wind their way through shrubs and small trees, adding brilliant blossoms to lush green canopies. In spaces too narrow for shrubs, clematis can screen unwanted views when grown on trellises. Create a statuesque element in the perennial border by planting clematis by an obelisk. Or consider a classic combination: clematis and roses.

Clematis anchors itself to its support by using the twisting petioles (stems) of their individual leaves. Trellises and arbors used to display clematis should include bars no thicker than the diameter of a pencil so they are small enough to be encircled by these two-inch stems.

If your structure is of bolder construction, attach chicken wire to the back to give clematis something to wind itself around.

Feel free to combine varieties. Two or more clematis on the same trellis can create a stunning display of colors or extend the bloom time.

Soil Preparation

Prepare the soil for your clematis by digging a hole at least a foot-and-a-half wide and deep. Supplement the soil with plenty of organic matter and plant the vine a bit deeper than it was in its pot.

If the clematis was growing on a small trellis in its pot, leave the plant attached to its support, and set the stake at an angle to direct the vine to the structure you've provided. If it was not growing on a trellis in its pot, set a stake near the root zone and lean it toward its means of support. If you have trouble with rabbits munching on your plants, take time to protect the stems on your new plant with a collar of protective chicken wire.

Pruning Requirements

Clematis have a variety of bloom times. The earliest vines to flower begin blooming in May on wood produced the previous year. Only prune these springtime bloomers to remove dead stems, or you will cut off flower buds.

Some clematis bloom on old and new wood. As a result, they have two flushes of blooms. To ensure the most flowers, only prune these types to tidy their form.

Late-blooming clematis begin to flower at the end of June or early July and continue to bloom until frost. These varieties bloom on new wood and should be cut back severely to encourage the production of lots of new flowering shoots. Prune these clematis in early spring, just as buds are beginning to swell. Starting at the ground, follow stems upward to the first strong pair of buds, and prune just above these buds.

Choosing Clematis

When selecting a clematis variety, keep the size and strength of your support structure in mind. Some clematis can grow as large as 30 feet. Others top out at just 2 feet tall.

If you plan to grow the vine through a woody plant, choose a variety that requires minimal pruning.

Clematis flowers range in size from miniature 1-inch blossoms to massive — almost salad-plate size — blooms. If you plan to grow clematis with a perennial companion, consider the color, size, and bloom time of both.

Viticella species clematis are loaded with small to medium flowers over an extraordinary long period — usually June through September. Clematis hybridized using texensis species parents usually have tulip-shaped flowers. Tangutica offspring feature bell-shaped flowers with almost leathery petals.

‘Jackmanii Superba' is the intensely purple variety that most people think of when they hear ‘clematis', but it is worthwhile to check out some of the more unusual larger-flower hybrids. You'll find varieties in tones from soft pastels to dazzling brights in just about any color to complement your color scheme.

Sweet Autumn Clematis is the family's late bloomer, filling the landscape with color and fragrance in September. It ambitiously grows up to 30 feet tall, but can be kept a little smaller if the stems are cut back to 12 inches in spring. First covered in pure white flowers, the vine becomes a mass of fluffy seed heads.

Like most vines, clematis come into their own in their third year. Slow to start, clematis will reward patient gardeners with years of spectacular blooms.

• Diana Stoll is a horticulturist and the garden center manager at The Planter's Palette, 28W571 Roosevelt Road, Winfield. Call (630) 293-1040, ext. 2, or visit planterspalette.com.