One of the most beautiful vines for home gardens, clematis is not difficult to grow but does need regular care. Proper feeding will encourage the vines to flower abundantly.
Ohio State University recommends feeding new plants with fertilizers with a 3:1:2 or 4:1:2 ratio the first few years to encourage rapid root and vine development. Using a fertilizer with that high a ratio of nitrogen can inhibit flowering, however, so you may not see many flowers while the plant is getting established.
Once established, clematis vines are heavy feeders and should be fertilized regularly. Switch to a fertilizer with a 1:2:1 ratio. These types of plant food are usually labeled as suitable for flowering and fruiting plants.
All clematis vines need to be fed in the spring to get them off to a good start. After that, the frequency of fertilizer application depends on the product used, so follow label directions carefully. As a general rule of thumb, organic fertilizers break down quickly and need to be applied more often than non-organic fertilizers.
Always make sure the soil around your clematis is moist before feeding. Applying fertilizer to dry roots can cause a chemical burn and damage the plant. Also, make sure that lawn fertilizer is not applied over the root zone of your clematis vine. Lawn fertilizers are high in nitrogen and will encourage leaf growth at the expense of blooms.