Specific PEHAM dendrimers are used in a formulation with an active agent for agricultural purposes, particularly for increasing the efficacy of the active agent in various ways, such as by improving solubility of the active agent in the formulation, by improving adhesion and penetration of the active agent to plant surfaces, by improving the water-fastness of the active agent to the plant or seed, by increasing soil penetration of the active agent to reach the plant roots or under soil parts, or by reducing soil adhesion of the active agent to reach the plant roots or under soil parts, or reducing enzymatic degradation of the active agent by the plant or seed or microorganisms in the soil.