Banker plants are those in which beneficial insects may reside, eat and reproduce even when there aren’t many pest insects to feed on. This is a key part in maintaining a successful integrated pest management system because without them the beneficial insects would leave once they accomplished their task.
Keeping banker plants in your greenhouses or gardens is a good way to ensure that your pest controlling insects stay in the area.
Recommendations are to use two banker plants per acre of greenhouse space and they should be established prior to putting them with your crop as it may take three to four weeks to start producing beneficial insects.