Indigo belongs to a large genus (Indigofera) by which is also shared with the pea. While this plant is better known for its dye making ability, it also is a wonderful landscape plant due to its colorful flowers that butterflies love. Depending on the species, this plant can be a shrub to a small tree in size. Since this plant is a tropical one, its USDA Plant Hardiness Zones are limited to mostly 6b to 8b but there are species that can have a broad range of 4b to 8b. Keep in mind though that in some warmer climates this plant has become invasive so prior to planting make sure to check with your state’s extension agent.
Propagating indigo through cuttings is not difficult and begins with finding that friend with an indigo plant. Once you have your indigo source and the permission, the next step is the prep. First, you will need to clean and sterilize your knife by soaking it in a pan of water with a bit of bleach added. After it has soaked for awhile, scrub to clean it and rinse in clear water. The next item on the to-do list prior to cutting is to decide if you are going to water root or plant in soil. Both techniques will be covered.
The simplest way to root your indigo cutting is through water rooting. What is required is a three to four inch cutting that has been removed from the mother plant at an angle. Remove all the lower leaves except the top one or two leaf pairs. Now, simply place your cutting in a glass or jar of water. When doing this though make sure that no leave touch the water. Change the water every other day and in about a week you should see roots. At this point the cutting is ready to be planted in a container.
If you prefer to plant your cutting in a potting medium, the process is the same but requires a few extra steps. First, clean and sterilize a shallow container. This is easily done like you sterilized your knife. Once the pot has been sterilized and is dry, fill with soil that has been moistened. Next, make a hole in the moist soil with a pencil and place one-third of your cutting in the hole. Move the soil around the cutting and repeat. As described above for the water rooting, remove the lower leaves.
After all the cuttings have been processed, mist the soil surface and place the pot on a sunny windowsill. In about a week your cutting(s) will show signs of new growth. This is an indication that roots have formed. Once this happens, plant the rooted cutting(s) in individual containers. Prior to moving to the garden, make sure to harden off the new plants.