To be sure your rain garden is working the best that it can for stormwater management, keep an eye on the inlet from the street. If seed and grass clippings accumulate, remove them. If erosion is occurring, consider installing flag stone or patio block at the inlet to reduce the erosion.
As well as being functional, your rain garden should be aesthetically pleasing. Your rain garden is a living community and will change over time. You may need to move plants, remove plants, and add plants to get the balance you want. If some plants are too tall along the street, you can move them to the back, or remove them altogether. Some species, such as sunflowers and coneflowers, can spread aggressively; these may need to be thinned-out.
Add new plants, if needed.
Cut and remove dead stalks and seed heads remaining from the previous season.
Divide and move plants if they are crowding the garden.
Prune shrubs, if necessary, in March or early April.