There are many resources available on edible and non-edible plants. Second, make sure the plants are not sprayed with chemicals not labeled for edible crops. When designing a garden layout, do not plant herbs or edible flowers near non-edible crops that might be sprayed with chemicals not recommended for edible crops. Over-spray or drift can contaminate the edible crop. If chemicals are used, read and follow all pesticide and fungicide labels carefully and use accordingly.
Constant observation is an important key to controlling disease and insects.
Be prepared by knowing what pests to look for and disease symptoms. Ortho Books offers a pest identification series for gardeners. Organic soaps and horticultural oils can be used to control soft-bodied insects, fungi, and mildew. During harvest, the plants are susceptible to damage from handling. Broken leaves and stems provide microbial infection sites.