my garden is mainly grassed it is fairly sunny most of the day untill about 3pm when it starts getting shady i have a bottle brush bush a yew bush and some lavender plants with some roses and nigella planted together and a passion flower that is growing through the bottle brush plant and some clematis it looks lovely in aprill and may and then it looks more and more untidy as summer goes on we would like plants that are fairly tough we have tried dahlias but these are quite high maintenance so any suggestions would be great