Clematis

Q. I bought a clematis last year. I don't know the type of plant I have. It is growing like gangbusters but I have no blossoms. I have 3 questions: What can I do to get the plant to blossom? Can I prune it this autumn if it doesn't bloom? It has grown so vigorously and extensively that I can't keep it at this size - it's in the way! If I can prune it how do I do it?

A. First the blooming season for clematis is over for the most part. The ones in Ohio peaked in May and are straggly in July. Here is what I recommend:

Vines need to become well-established before they will bloom. Do not worry. The fact that it is growing well bodes well for the future flowering. Continue to water the vines well and feed them with a general garden fertilizer for foliage as a 30-10-10 or 20-20-20 once every three weeks at one tablespoon per gallon water. This will build up the plants and strengthen the root systems.

Clematis like their roots cool and shady with their foliage in full sun. They prefer rich well drained soil and make good companions for roses. They will grow near water as long as they are planted well above the waterline and can get their roots down to the water if they want it. When planting it is best to prepare the hole sit the plant in position and cut away as much of the plastic as possible. This will leave the bottom of the bag in place but avoids unnecessary root disturbance. Stake the plant then back fill the hole and firm it in gently.

One of the most important aspects of Clematis culture is the pruning method. Remove dead wood and prune to shape after flowering to 3-5'. A general cleanup of weak growth after flowering is also beneficial. All summer trim any poor or dead growth to provide more light and nutrients for the healthy stems.

As a general consideration 3 - 5 year old growth buds on old wood will die completely so every few years a good cleanup directly after flowering is required. This will make sure you can see the best growth buds to cut back to and maintain a relatively young healthy framework. Give a good feed of compost and bonemeal at pruning time as well as fresh mulch to prevent soil splash.

Watch for clematis wilt caused by soil splashing onto the stem easily prevented with a mulch of bark compost gravel or anything that prevents soil splashing around the stems. Deep planting allows the susceptible forms to develop a crown of growth buds below ground level and since the wilt disease affects the stem at ground level or just above healthy new shoots from below ground can restore the plant very quickly if attacked by the wilt disease. When watering in summer it is best not to wet the foliage but trickle the water around the base of the plant and give a good deep soak twice a week.

Q. Should I trim back my climbing clematis now or do I wait until summer?

A. I do not know where you live but no pruning should be done until spring has started and the danger of frosts in your area are over. Otherwise you would be encouraging new growth which could be killed by the cold temperatures.

Clematis likes some early spring attention and pruning your plants at that time will encourage more vigorous plant growth this summer. For those large summer-flowering clematis types prune the plant's new shoots to about 12" from the soil line. For older clematis plants cut all stems back to just above the previous season's growth.