Nanotechnology is providing exciting advances across many fields but to date has had little impact in the plant sciences. Using nanotechnology to influence plant growth and development is a relatively new concept. The manipulation of fundamental plant processes via the application of nanoparticles that can deliver a range of biomolecular cargo has the potential to protect plants from biotic and abiotic stresses such as disease and drought. Our group is undertaking research to characterise and optimise both nanoparticle type and structure and their retention in plants for the delivery of agrochemicals. We have used model plants including Arabidopsis, wheat and maize, to demonstrate that silica-based mesoporous nanoparticles are taken up and mobilised and that this can be exploited for the targeted delivery of a molecule of interest. Our studies show how these nanoparticles interact with plants, where they go and how they can be used to delay the release of molecular cargo. We now have an understanding of nanoparticle interaction and uptake pathways in plants and how the particles may be manipulated. A further approach has involved loading agrochemicals into nanostructured liquid crystalline particles that are self-assembling cubosomes and hexosomes. Through understanding their adhesion to plant surfaces we have successfully designed materials that greatly improve the efficiency of, for example, herbicide delivery. Nanoparticle delivery of bioactives thus provides an innovative way to modify biotic and abiotic stress in plants.