I have vivid memories of my grandparents' front porch in summer. It was always packed with an assortment of containers filled with plants. Old coffee cans, plastic pots and the occasional ceramic florist cachepot all served as worthy vessels. I now realize that all of the plants were propagated from cuttings that were given to my grandparents. Plants such as purple heart, coleus and sweet potato vine were favorites because they rooted easily. In fact, many of the plants on my grandparents' front porch were propagated in plain water.
The process is really simple. All you do is take a cutting from a plant that is about 4 to 5 inches long. Remove the lower leaves, but keep some at the top. Then place the cutting in water.
I advise using a ceramic container rather than one made of clear glass because the lack of light helps to promote more root growth. It's also a good idea to refresh the water every 7 to 10 days.
Now if you really want to stimulate, even accelerate, root development you can do this by using an old fashion solution called willow water.
The cuttings are ready to transplant when the roots are about 1/2 to 1 inch long. To move your cutting to its new home, hold it upright in a container and pour dry potting soil gently around the stem, covering the roots. Water the plant well and then place it in a humid, brightly lit location until you see new growth. If humidity is an issue, place the pot in a saucer filled with gravel and water.
Not every plant is suitable for making cuttings this way. But some of my favorites include old-fashioned "chicken gizzard", ornamental sweet potato vine, coleus, angel wing begonias, philodendron and plectranthus.