Q.When and how to prune my clematis plants
Hi,
First let me say I’m a real fan of your website. I’ve made my own potting soil using Coco Coir and am currently using Diatomaceous Earth as many of my seedlings are being brought indoors and have so far just notice aphids on some of them.
Now to my question: I have two clematis plants that are 4 years old. The first two years they never to more that a couple of feet tall with just a few beautiful purple flowers. However at the end of last years growing season I used some rose food and they showed a little life. This year they have taken off and grown about 8 feet tall. However, not one flower and as it is getting pretty cold at night (I live at 7000 feet) and other than mulching them, I’ve never been clear as to which pruning I should do. I’ve read that there are 3 different approaches to take in pruning, but since I’ve only had poor growth and just a few flowers in the past I’m not too sure which approach to take.
Any suggestions from you folks would be greatly appreciated.

Certified GKH Gardening Expert
If you can figure out the name of your clematis such as Jackmanii you'll be home free. You can look up the pruning information for that named variety. If not, you'll need to wait till they bloom to know which group they are in. They typically bloom in spring, summer or fall, or hybrids that bloom twice.
The safest time to prune is immediately after the vine finishes blooming. Then you don't have to worry about cutting off next year's blooms (some bloom on old wood or previous year's growth). Some of the large flowered hybrids bloom twice so that is trickier.
These articles should help:
https://www.gardeningknowhow.com/ornamental/vines/clematis/pruning-clematis-vines.htm
https://www.gardeningknowhow.com/ornamental/vines/clematis/getting-clematis-to-flower.htm
https://www.gardeningknowhow.com/ornamental/vines/clematis/types-of-clematis-plants.htm