Forsythia are very low maintance and easy to start from cuttings...last summer I snipped a few branches from my neighbours bush, I put them in a bucket of water and well, I know it seems too easy, but I just left them there for a year, making sure the bucket never ran dry, that's it. Only one of the four branches grew roots but that's OK, I'll snip some more this year, in the bucket I place all sorts of cuttings, some take some don't, but it's so effortless that it'w worth a try.
This is my "cuttings bucket", at the back of the house, out of sight and the hot sun. I have a cutting from an unknown bush which growns outside my diner but love the berries...I hope it roots!
As you can see the forsythia grew quite a large root ball over winter.
An a bonus...a new shoot.
I planted the cutting in some compost and new soil at the edge of the yard hoping to create a privacy fence.
The hot dry summer may kill your new cuttings so it's best to plant cuttings in the spring and fall as new plants need lots of water.