Weed-free organic material is preferred for mulching so that it enriches the soil as it decays. Most pest control should be done by hand and without chemicals to avoid the danger presented by working with toxic substances. However, if chemicals are needed, contact your local extension agent for specific recommendations. Careful observation and prompt action can alleviate most pest problems. If weeds are kept down through mulching and pulling as soon as they are identified, they will not become invasive.
Insects can be a big problem with some plants.
Make sure all plants are insect-free before planting. Remove by hand any pest that is found. Disease can also be a problem with certain varieties. Use plants that are resistant to problem diseases in the area. If just one portion of the plant is infected, remove and destroy that portion, do not compost.