Which technique was used by Mendel for hybridization?

The technique of interbreeding two different species to produce offspring (hybrids), with characteristics from both parent species is referred to as hybridization.

Gregor Mendel used emasculation and bagging techniques for his hybridization experiments.

During emasculation, he removed the male reproductive organs from a plant's flower before it produced pollen in order to prevent self-fertilization. While bagging, he covered the plant's flowers with a bag before they opened to prevent pollination by other plants. 

Mendel was able to control the parent plants that produced the hybrid offspring and ensured that the offspring were only produced from a cross between two specific varieties of plants.