Why use rooting hormone on plant cuttings

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.

How to use rooting hormone

Start with a freshly cut stem of new growth. Powder rooting hormone is easy to apply. I transfer a small amount of hormone rooting powder to another container (a small plastic cup or paper plate). This prevents potential contamination of the bottle of hormone powder.

If it has been more than 30 minutes since you collected the clipping, moisten the tip by dipping it into clean water. Next, dip the tip of the cutting into the rooting hormone about 1/2 inch or according to the manufacturer's instructions. Tap the cutting on the side of the container to release excess hormone powder.

Use your finger (or a pencil) to create an indentation into the potting container soil. Drop the hormone-dusted cutting into the hole and water gently to settle the soil around the cutting.

How long does a container of rooting hormone remain active?

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.