Requirements for taking Dahlia cuttings: a sterile razor sharp knife, some type of enclosure to retain significant humidity and at the same time have some degree of air movement, some type of very moist growing medium(anything from pure sand to potting soil). You are allowed to be creative with any of these items, as long the basics are present. Some type of rooting compound can be used but it’s not mandatory. A room temperature and/or some bottom heat of at least 70 degrees is important. When your
new tuber sprouts are three to four inches high you are ready to take your first cutting. Use the flame sterilized knife to cut the stem at a 45 degree angle just below the base node or one sixteen of an inch above the tuber. New tuber sprouts will begin to grow in about a week. Make a pencil hole in the planting medium and insert the new cutting as quickly as possible. Do not pack down the soil too tightly as the cutting needs air to support the new root growth. Initial light isn’t mandatory, but after a week they should receive good indirect light, but no direct sun light.