This paper presents a method and system to artificially pollinate flowers using Unmanned Aerial Vehicles (UAVs) called pollen drones. Pollen drones can be of any size and number depending on the area covered by the flowers to be pollinated. They are special UAVs fitted with appropriate means to collect, carry and apply the pollen to the target female flowers. In executing their job, the pollen drones can work collaboratively and autonomously or can be guided by a ground station. The present method can find its use in the area of agriculture for increasing the yield of plants and trees, in particular, of tall trees