A delayed release delivery system comprises a hydrophilic core particle having surface pores and containing a liquid. The particle is encapsulated in a polymer having a hydrophobic backbone and hydrophilic pendant groups. At least some of the surface pores adjacent the hydrophilic pendant groups are blocked in the presence of water and unblocked in the absence of water. The treated particle contains liquid in a weight ratio of the liquid to the porous core particle of at least 400:1.