Question
Q 1)I planted a new climber "Leverkusen" in full sun at the top of a slope in early May. It was bare root. It is growing fine and has buds, but the new growth is very yellowish, rather than green. I have kept it well watered and put aged cow manure round it.
Q 2) Other roses I have had planted for years did not overwinter well, when I protected them the same way I always do (in other words - no change from other winters when they have flowered very well). Some are fine and some are going to have very few flowers. Was this a hard winter for roses?

Answer
I don't think there is anything wrong with Leverkusen. The reason I say that is because this rose does have a greenish yellow shade of leaves. I have two and both look more yellow beside the other roses. I would wait and see if the leaves actually turn all yellow and then get back to me. If you have very cold winters then you need to plant your roses much deeper than the rose books tell you. I would plant all my roses in your area at least 6 inches deep from the top of the roots. So that means the graft is 6 inches under the soil. Then I would heap 8 inches high of compost, bark mulch or even soil from another art of the garden as talking it near the rose can expose the roots when it gets nasty in the winter. Just make a mound all around the rose bush. I don't know what area you garden in, but many people in all areas of the States did get unusual winters. It is not always the winter which causes dieback or even kills a rose, it can be the early spring when the rose starts to grow and then you get a hard frost for a few days. That will do harm to most roses.