I have a weigela in my yard that I did not plant. Last year's growth rarely comes back. Some years I don't even know if it is alive until July. This year I have a couple of blooms just now in September. I have varied my attempts of pruning from not pruning it to severe pruning. It doesn't seem to matter. Any ideas on what I can do ?
This would be a "volunteer" plant, meaning it probably grew from a seed dropped by birds. Unfortunately, these plants rarely flower very much. The weigelas that flower so beautifully are grown from cuttings of plants that are outstanding bloomers. If you want one, my advice is to cut down your volunteer and buy a nice bush to put in its place. This article has some more information: https://www.gardeningknowhow.com/ornamental/shrubs/weigela/growing-weigela.htm