I've got a group 3 clematis on an oblisque that has flowered nicely but it only has 1 stem coming out of the ground that then branches out and covers the support. Is there anyway to encourage it to put out more stems? If i cut it back hard there will be no greenery just 1 brown stick ?
When you cut it right back in late winter/early spring, it should produce more stems each year from below ground as it matures. Assuming it was planted nice and deep to start with
You'll need to feed it too. They are hungry plants so prune back to the lowest new pair of buds next spring and give it a generous handful of specialist clematis food or rose food and give it regular liquid tonics of tomato food between spring and early July. It should then produce new stems and plenty of flowers. Repeat very year.