I've always thought of gardening as a green activity, but there's an argument that some of the things we do when we garden are not necessarily as green as we might think. Consider our use of gas-powered equipment, over-application of fertilizers, and careless use of pesticides.
There are things we can do to keep our gardening efforts more sustainable with less of an environmental impact.
We can raise our tolerance to damage from pests and disease. If it's not life-threatening or liable to cause serious damage, and if the plant will get over it on its own, we might consider not using pesticides. We can use native plants. They're adapted to the pest problems we encounter locally.