Unlike most plants, sutera will not wilt when drought stressed. Before the plant shows signs of wilting it will drop both the flowers and the buds on the plant. It takes about 2 weeks for the plant to come back into bloom after it has been drought stressed. To maintain constant bloom you will either need to monitor the plant closely and water before the soil gets too dry or you could plant sutera with a plant that does wilt. Some good plants to consider are verbena, coleus, petunias etc. These companion plants will serve as indicator plants to let you know that the sutera is dry and should help you avoid having the plant dropping blooms and buds due to drought stress.