Answer: The most common problem with vines that produce an over abundance of green growth and no flowers is a nutrient imbalance, usually too much nitrogen. It is best to fertilize clematis with organic, slow release fertilizers, usually in late February or early March. Fertilizers are characterized by 3 numbers representing the relative concentrations of nitrogen, phosphorus and potassium (N-P-K), in that order. Plants use nitrogen to grow foliage, phosphorus to develop root systems and form fruit, and potassium to promote flowers and develop resistance to disease. Choose a fertilizer with a low nitrogen number relative to the phosphorus number, such as 5-10-10, so that your plant will develop blossoms and roots, rather than lots of foliage. Some bulb or tomato fertilizers have concentrations similar to this. A second dose of fertilizer is recommended in June. Encapsulated three month slow release fertilizers are also a good choice. In general, clematis likes its head in the sun and the roots in the shade so they remain cool and moist. Hope this information helps!
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