My Third Year of Gardening So, a lot of flowers came back this year on their own. I learned that if I leave my petunias alone, they will grow and bloom wonderfully on their own. Yes, they do need pesticide spray. The colors on this plant are miraculous. Irises - These flowers are resilient. They come back in full force during spring. And they spread their seeds. I have Asiatic lilies in my flower beds and they started out with 2-3 flowers, but this year, they came back with 8-9 flowers. I'm expecting them to multiply next spring. Swap out dead flowers and feed the new ones with Miracle-Gro food and spray a pesticide on them.