During a recent volunteer work day at Pendleton King Park -- where you can see a fabulous variety of hydrangeas -- recent master gardener graduate Tom Mills led a session on propagating hydrangeas.
First things first: Remember that some plants are registered, which means you cannot propagate such a plant and sell it. You can do it for yourself, though.
Propagating by cuttings is easy to do. Tom explained that you can use potting soil or any sterile planting material such as vermiculite or coarse sand.
Take a cutting 5 to 6 inches long from a branch. Remove terminal bud at the tip if present, then remove lower leaves, leaving only two or three which you need to cut by about half. If you are taking several cuttings at once, be sure to have water available to keep the cuttings hydrated.
You can use rooting hormone on the end of the stem, but it's not necessary. Insert it into moist soil and create a tent with a clear plastic bag to enclose the cuttings and pot. You need to use sticks or other devices to ensure the plastic doesn't touch the cuttings. You need to keep the soil moist but not soggy.
Set cuttings in a shady area and leave them alone for at least a month. Be sure to label, Tom advises, because all cuttings are going to look alike. Check for root growth by pulling gently on the stems. Any resistance means you have roots.
If you don't want to wait or prefer to start with larger plants, there's a simple way to propagate: layering.
As Tom demonstrated, all you really need is a brick. Find a low-hanging branch that can reach the ground easily. At the point where it can touch soil, scrape away the other layer of the branch and use the brick to hold the spot in contact with the soil. Leave it for four to six weeks and when you check again, the branch should have sprouted roots at the contact point. You can then cut branch from mother plant, dig up roots and pot it up.
If you check your plants you might find they have layered new plants. I got a couple of hydrangeas for the Pendleton King Park plant swap this year by checking my bushes. The plant swap is a great way to get more plants next spring.