For best results start with easy herbs like mint or basil which will root in only few days, but you can also try rosemary, oregano, marjoram, sage, lemon balm or lavender.
Start by choosing a healthy stem that has no pests or diseases on it and preferably a non-flowering one. Cut the stem using a sharp knife or secateurs, 10-15 cm long and just underneath a node. Stripe off the leaves from the lower part of the stem so no leaves will be under the water level and cut down any flower if it has any. Then and place the stem in a bottle or glass full of water and put it on a sunny window sill.
You can use all sort of bottles and glasses to place your cuttings in. Propagating herb cuttings in water is an effective way to grow herbs but in the same time is a great way to recycle old and funny bottles or to display a vintage bottle collection on your window sill.
Make sure you change the water every couple of days so it will be clean, fresh and free of bacteria, else the stem will rot instead of rooting. In about a week or so you should see the roots, depending on the herb you try to propagate. Some may take longer.
After the roots start to appear keep an eye on your plants and don’t let the roots grow longer than 5-10 cm because else they will be hard to plant out in the soil. The roots grown in water are quite fragile and brittle so when you transfer them into the soil make sure that you make a hole in the compost large enough so that you don’t squash the roots too much. Keep the pot in the shade for about a week until the plant get used with the new medium and is well established. Grow them on and use after the plants are showing good growth.