Hi Begonia and welcome!
You are a bit late for softwood cuttings (early summer) but hardwood cuttings can be taken in winter.
Something else you can also try though and now is the best time to do it. Look round the base of your hydrangeas and see if there are any branches lying on the ground. Gently lift them up and if you feel any resistance they may have become self layered and rooted . If so carefully dig the branch up with as much rootball as you can and sever the main stem from the parent plant. Plant your new treasure in well prepared soil with 50% compost mixed in with the backfill.
There you go! Instant propagation!
You can layer most shrubs. Take a young flexible branch down to ground level, dig a hole about 4" deep, bend your branch into and out of the hole so that the growing tip is exposed. Scrape some bark off the branch where it will be covered over in the hole, 'peg down' with a U shaped piece of stiff galvanised wire and then cover with soil and compost. I generally place a house brick on top as well to prevent any movement of the new rooting area in windy weather and it keeps the tender rootlets cooler in hot spells. It takes time for layering to develop root so leave alone for 6 months to a year and your new plant will then be ready for severing and replanting. For some otherwise difficult plants its the safest and most reliable way of propagation.