When and how should I prune roses in early spring?

Wait until buds start swelling (late March to early April in zones 5-8, or when forsythia blooms). Remove dead, diseased, or crossing canes, then cut remaining canes to 12-18 inches tall at a 45-degree angle above an outward-facing bud. Leave three to five strong canes. Be ruthless — a pruned rose looks like a sad stick but will reward you with more blooms.