I have two type 3 clematis growing up a trellis in my garden, and doing fantastically well. I don't really want to prune them, because they are providing a 'green wall' between two parts of the garden. What will happen if I leave them unpruned?
A birds nest will form.
Group three are vigorous and will shoot new growth from every leaf axial, which will multiply existing stems by tens of dozens, if not hundreds. Now this sounds all fine and dandy, and may even be bearable for a year or two but the plant will eventually stop flowering anywhere beneath new growth which will end up way above your eye line with support, or as a flopping snappy mess without support.
Choice is yours really
Edit: spelling mistake in previous post should read leaf axil...you know what I mean
P.S, a thought might be to cut back some stems but leave others tied in, thus you can control the size and shape of the plant to fit your tastes.
If you leave it unpruned it will develop stems that are woody, of which have no foliage or blooms. Not nice to look at, IMO.
Group 3 - should be pruned back severely every year in late winter, when they are completely dormant, to about 12 - 14 inches. Leave at least two pairs of buds on each stem of the plant. This group are very fast growers and usually reach they full height before each summer.
Hi Bridget, I agree with the previous replies. What you could do is plant a third clematis, but a group1 (no pruning). This will give very early flowers (usually March) and you could train it to grow interspersed between the other two, to cover the lower areas that will become bare. Once it has covered a fair area (a year or two), you could cut the group 1 types back to the recommended level, or even to ground - they usually come back fine if you do that.
Christopher Lloyd and the people at Tenbury suggested growing 2 Type 3 together. Ony was pruned every year as recommended to give flowers at a lower level, and one was left alone to flower at a higher level and obviously a little earlier. The pruned one hid the bare legs of the other.
Do you know which varieties you have? There are some bred for pot culture which only grow to about six foot, and don't need much pruning at all, permanently staying fairly small.
Thanks to all of you for your help - what a wealth of knowledge! I have got some type 1 clematis growing alongside the type 3s, so I am getting some earlier flowers as well, but can't remember what variety of type 3s I've got. I think some judicious radical pruning of the type 3s is in order, leaving a few longer stems to cover the trellis.
Again, many thanks to all of you, and I hope I can return the favour some day!