Be aware of the signals that your plants are emitting. If you have plant material that is just not flourishing to be all that it can be, there could be several reasons for the problem. Perhaps the plant is not getting enough nourishment, and there can be a bunch of reasons for that. Survey the surrounding plant materials for your answers. Perhaps a neighbor's nearby tree which was just a sapling a frew years ago is now a big strong tree with thirsty roots that are sucking up all of the water. In any case you have two choices:
a. You can commit to watering that area more often to make up for the void, or
b. You can move the plant to another area of your garden where there is less competition for nutrients.