Taking cuttings of your favorite flowers or shrubs? Increase the rooting success rate of plant cuttings by using rooting hormone—at least that is the marketing angle of manufacturers of rooting hormone.
What is rooting hormone?
Rooting hormone is a synthetic compound mimicking nature’s ability to produce roots. The rooting hormone stimulates the cells to produce roots. Can a plant produce roots without the benefit of rooting hormone? The answer is yes. BUT, using rooting hormone can increase the volume of roots, which increases the growth potential of the cutting, and ultimately life potential after planting.
In the picture shown above, these two mum cuttings were set the same day. Each had four leaves. For the cutting on the left, I used no rooting hormone. Now, about five weeks after planting, the hormone-treated cutting on the right has more new leaves than the untreated cutting. Better yet, the plant on the right has a denser root system. Each will most likely grow in a pot or in the ground, but the cutting grown with rooting hormone with its dense rooting system has a better chance of survival. In addition, in the case of mums, the healthier hormone-treated cutting should create a robust flowering mum for fall.
Types of rooting hormone
Rooting hormone is available in powder, gel and liquid form. My experience using gel showed a reduced success rate due to rotted cutting stems. Liquid rooting hormone may be pre-mixed in water or alcohol, or the liquid formula may be a concentrate that requires dilution with water. I prefer powder rooting hormone, which is a talc-based product blended with less than one percent artificial hormone.
Some plants produce hormones naturally and do not need artificial rooting hormone to promote root growth. To ensure the type of rooting hormone you choose is suitable for the types of cuttings you grow, read the container label. The label may list the specific plants cuttings that benefit from rooting hormone.
Guidelines indicate a need to replace the rooting hormone annually due to short life of active ingredients. I have used the same bottle of powder rooting hormone for two years and will continue to use it until my success rate of rooting cuttings drops.
Store the bottle in a cool place, like in the refrigerator. Place the bottle in a sealable plastic bag before putting in the refrigerator.