How to do grafting propagation of rhododendron?

Grafting usually splits at the top of the shoots, and the time is May-June. The rootstock is Rhododendron pubescens or its varieties, such as "Violet pubescens", "Jade Butterfly" and "Purple Butterfly". 2-year-old single plants were selected as rootstocks. Cut 3 ~ 4 cm shoots from Xi Juan mother plant, remove the lower leaves, leave 2 ~ 3 upper leaves, and cut the base into a smooth wedge shape of 0.5 ~ 1 cm. Cut the rootstock buds into 3 ~ 4cm, remove the leaves, cut about 65438±0cm longitudinally from the flat incision, insert the scion, align with the cambium, tie it tightly with plastic tape, then bag it, and keep warm and moist. Other methods include cutting, butting and budding.