To get more benefit from the predators and parasites that nature provides, as well as for those you release, use plants that will have flowers year 'round to provide food for our allies in the insect world. These plants are best placed in areas that scattered throughout the farm and can be planted in areas that currently not used for cropping, like gullies, along roads or windrows, by buildings, etc.
There is a seed mix available that is designed for California growers to contain a plant mix that will have over-lapping flowering periods all year long. It includes legumes, yarrow, fennel, alyssum, and many other plants. For more details, contact the companies below.
This mix is made by Lohse Mills, and is bought in bulk and repackaged by Harmony Farm Supply, so choose the size that is best for you.
Lohse Mills's Benefical Blend, $3.10 / lb. in 50 lb. bags: 530-934-2157
Harmony Farm Supply's Insectary Blend, $3.25 / 4 oz or $47.20 / 5 lb. bag: 707-823-9125