The way I have done it with weigelia, has worked very well for me. I wait till blooms alomst done, and you have some good new growth on the ends of the branches. Cut a piece about 1/2" below the lowest set of leaves. Pull all leaves off, but about 2-3 at the end of the stem. Usually mine are about 6" long. Then dip the end in rooting hormone, and plant. I have a small bed next to the back of my house with hostas etc. It only gets early morning sun, the dirt stays moist, and fairly loose. I put most cuttings in this bed, and forget about them. I even get roses to root here.No jars on top or anything. The hosta's and bleeding hearts etc provide some shade and protection, but still allow air flow. The weigela has rooted very easy for me, and is a very fasr grower.
Tammy

My Weigela layered itself last year, so this year I am air layering 5 branches. I have done this with success with Red Twig Dogwood, so I wanted to try it with Weigela. I should try ground layering it too. It'll be a lot easier.

I have had more success layering than cuttings.