To get a performer to come out for an encore, you need to stand and applaud until your hands are red and hot and achy. Flowers do not respond to this kind of attention. If you want to get a second show out of annuals, you have to rip their heads off. So this weekend in the garden, make your rounds and pinch back all of your snapdragons and petunias. If your herbs are flowering, cut the blooms immediately. Summer’s coming, people. Take no prisoners.