Clematis grows as a tall, twining vine. The vines are covered in attractive green foliage throughout summer, but their flowers are their main feature. Some varieties only flower for a short period, while others provide several months of color. These hardy vines grow well in most climate areas and each plant can live as long as 25 years or more.
Plant clematis in a bed that receives at least six hours of sunlight. The vines tolerate some afternoon shade, especially in areas with high summer temperatures. Choose beds with well-drained but moist soils, as clematis doesn’t grow well in overly soggy or dry beds. Amending the soil with compost and other organic matter improves the quality of the planting site. If your clematis bed isn’t already near a fence or structure the vines can climb, install a trellis prior to planting.
Clematis requires 1 inch of water a week in spring and summer when the vines are actively growing, from either rainfall or irrigation. Water deeply at the base of the plants, moistening the top 6 inches of soil at each irrigation. Once to twice weekly watering is usually sufficient, though you can water less in weeks when it rains. Applying a 2-inch layer of mulch over the soil helps retain moisture in the soil so that it is less prone to drying out.
The vines benefit most from fertilization during the first two years after planting. Apply a 1/2 lb. of high-nitrogen fertilizer, like a 15-5-5, to every 50 square feet of bed when you first plant the clematis and again in the second year. Once the vines are mature, excessive fertilizer can harm the vines as they are able to get most of the nutrients they need from the soil.
The time to prune depends on your variety of clematis, but all types benefit from yearly trims. Prune plants that produce large flowers in June in late winter before new growth begins, removing damaged stems and cutting back the remainder to the leaf buds nearest their tips. Trim spring-flowering clematis as soon as they stop flowering, removing up to one-third the vine’s length. Cut back late-flowering clematis in later winter before they begin putting on new growth. Prune each stem back to within 2 to 3 feet of the ground to encourage a flush of new growth.