Posted: 02/10/2014 at 07:18
All clematis are thirsty, hungry plants. As long as theye are planted deeply enough theye don't need shaded roots but they do need food and water. You may not have teh same good soil as grandma so I would advise you give the plants a good mulch of well rotted garden compost now and again everys pring as well as a handful of blood fish and bone around the roots in spring and a liquid feed of rose or tomato food.
The other thing to note is that both of these are group 3s which means they need to be pruned back hard in spring to a low pair of buds on each stem once the worst of the frosts are over. You then remove all the brown, woody stems and feed the plants as above and they should grow fresh new stems which will flower all summer.