Yes. “Chatting up your plants means that you’re breathing carbon dioxide on them. Plants absorb that carbon dioxide during photosynthesis to make food for themselves,” says Sydney Eddison, a lifelong gardener whose new book, Gardens to Go (Bulfinch, $35, available on www.amazon.com), is due out April 2005. But the obvious reason is this: “A plant that’s talked to is simply a plant that’s paid attention to,” says Eddison. “If you’re talking to a plant, you are most certainly aware of its condition.”