Our recently purchased home has a lot of old fruit and vegetable plantings that were mostly left alone for the past few years. Among these is a set of three grape vines on a group of metal trellises. We've cleared out the weeds that were growing around the vines, as well as some competing climbing plants that had gotten up onto the trellis and intertwined themselves with the grape pretty badly and took over a big portion of the trellis.
So right now the grape trellises are pretty clean and the vines appear to be healthy, although they're very unevenly distributed over the structure. What should we do now to encourage future growth and get the vines to spread out? Are there any companion plants or other fertilization techniques we should look into. We'd like to avoid chemical fertilizers if possible.