We planted/replaced a dozen or so thornless loganberries against a north facing wall a year ago. We removed the old (40 yr +), dug a deep trench, enriched it with manure, peat, compost and bonemeal. The new plants grew at a fantastic rate, reaching to the top of the wall (8ft approx) and we trained them back down again towards the earth. None of them produced any fruit, but that was what we expected would happen. Now should we have pruned them before they grew too tall, prune them now before they start into leaf - there are plenty of buds on the plants or just leave them as they are now?