Clematis is a flowering vine available in hundreds of different varieties. Bright blooms make them a focal point along garden fences and trellises. Clematis vines are divided into three groups: early-flowering, large-flowered hybrids and late-flowering. Early-flowering clematis bloom in April and May. Large-flowered hybrids bloom twice in the summer. Late-flowering clematis blooms from summer to fall. A clematis vine may fail to bloom for several possible reasons.
Lack of sunlight can contribute to a clematis vine not blooming. Clematis requires at least 6 hours of sunlight each day. However, certain varieties such as 'Hybrida Sieboldiana' and 'Hagley Hybrid' prefer partial shade. Follow the instructions provided on the plant identification tag, on the side of the pot or stuck in the soil.
Poor soil drainage and incorrect pH levels could be reasons the clematis isn’t blooming. Clematis prefers a well-draining soil. If water remains on the top of the soil 30 minutes after watering, the soil is not well-draining. Consider adding peat poss or other organic material to the soil in order to help with drainage.
The ideal pH level of the soil is 7.0. Soil tests, available through extension offices or garden centers, can determine the soil's pH level, along with what nutrients are lacking. Adding these missing nutrients to the soil helps the clematis produce blooms.
Pruning is the process of removing dead branches and weak stems to help promote new growth and blooms. Early-flowering cultivators should be pruned after they bloom in April and May. Prune large-flowered and late-flowering clematis in March. Clematis vines that are not pruned may not bloom as profusely as those that are pruned, if at all.
Fertilizer may help clematis bloom, but too much fertilizer can prevent it from blooming. Fertilizer should be applied only once per year. Fertilizers are available in powder and liquid form. Selecting a fertilizer that is high in phosphorous will help promote bud and root growth. Follow the label instructions carefully to prevent fertilizer burn.
Keep in mind that many clematis varieties do not bloom during their first year of growth, when the roots are getting established. Clematis vines do not like their roots to be disturbed. If possible, don't dig around clematis roots if the clematis is planted in the ground. Consider keeping it in a container, and insert a trellis to help with climbing. Clematis vines may last 25 years or more.