The term "insectary plantng" refers to the use of flowering plants to attract the natural enemies of crop pests. Providing resources such as pollen and nectar for beneficial insects creates a welcoming habitat.
Insectary plants can be included in your edible garden plan, as well as your greenhouse or cold frames in the same manner that commercial organic growers incorporate these plantings in to cropping systems.
There are several ways to incorporate insectary plants. Within the crop in strips or smaller blocks, if you are using a traditional bed system for example. As a hedgerow, or border, or as perennial plantings.
A well planted insectary bed can attract beneficial insects such as lady beetles, hoverflies, parasitoid tachnid flies, predacious wasps, soldier beetles, parasitoid wasps and green lacewings. These plantings also attract spiders, ground beetles and other bugs that are common natural enemies.
There are several factors to consider when designing insectary plantings. The most important for the home gardener are bloom succession, or the timing of flowers, and knowing the characteristics of the beneficial insect you wish to attract. You may also want to consider the cost of seeds and establishing the planting and whether the planting can be harvested as an additional crop. Coriander, or cumin, for example is excellent for attracting predacious wasps.
Often these types of plantings are called companion plantings for the home gardener. Common companion plants are alyssum, nasturtium, marigold and allium. You can easily extend your insectary planting by adding flowering herbs and designing a natural landscape, where flowering and edible plants are interplanted.