What Is A Rooting Hormone

What Is A Rooting Hormone? Is It Necessary And How To Use It?

In Propagation by Ana M

Propagating your favorite greenhouse plants from cuttings or seeds requires a set of skills and passion. It is a mesmerizing experience to watch your cuttings sprout. Although, sometimes out of ten cuttings only one might end up growing into a new plant. Of course, there is always a chance to fail, but many growers found a solution and swear by rooting hormone.

Never heard of it? You came to the right place! In this article we will find what is a rooting hormone, whether it is necessary to apply it to cuttings and if so, you will learn how to use it.

What is a rooting hormone?

In nature every plant has plant hormones found in stem and root tips that promote cell division and accelerate root growth. The element that controls plant development is called Auxin. The most common Auxin naturally present in all plants is indole acetic acid (IAA), chemically it is a weak organic acid.

So, a rooting hormone is a commercially available product in either gel, powder or liquid form. The most widely used Auxins for synthetic production are 0.2% indole-3-butyric acid (IBA) and 0.4% 1-naphthalene acetic acid (NAA).

Is rooting hormone absolutely necessary?

The application of rooting hormone is not absolutely necessary, for example, you can have a high success rate when rooting cuttings of plants with non-woody stems, like Fuchsia, without hormone. However, you need to use rooting hormone when rooting cuttings from hardwoods like dogwood.

rooting hormone is not necessary, Fuchsia cuttings from without hormone

Moreover, rooting hormone is not only used to improve the development of roots, it increases the percent of rooted cuttings and makes rooting system stronger.

When it comes to choosing a rooting hormone, most of the gardeners face two very popular options: rooting gel and rooting powder. What is the difference and which option is a winner?

Clonex Rooting Gel and Garden Safe Rooting Hormone Review

What is better - rooting hormone powder or gel?

Number 1 – Composition.

Let’s start by looking at the active ingredients. In both HydroDynamics Clonex Rooting Gel and Garden Safe Rooting Hormone powder the active ingredient is indole-3-butyric acid (IBA). The first option contains 0.31% of IBA and the powder comes with 0.1%. Both products identify the rest of the composition as ‘Other Ingredients’.

However, when researching it further Clonex claims that their product is a special blend of minerals and other helpful ingredients. In a meantime Garden Safe doesn’t mention anything about other ingredients and product users came up with suggestions that it might be bonding powder or talc.

So, in this category gel rooting hormone has more active ingredient (0.31% IBA) and the product is water-based with the rest of it made of a full spectrum of mineral nutrients and trace elements to help plant in the early development. However, let’s keep in mind that Garden Safe brand is known for natural-based and botanically derived formulas.

Number 2 – Volume.

Gel rooting hormone comes in 3.4 oz (100 ml) and net weight of Garden Safe rooting hormone powder is 2 oz (56.6 g).

Number 3 – Price.

100 ml of rooting hormone gel costs 18.36$ and 2 oz of rooting hormone powder is 4.54$.

Number 4 – Shelf Life. Does rooting hormone expire?

Clonex is guaranteed to last for 2 years if stored in the original packaging in a refrigerator when not in use. Also, you need to make sure not to dip the cuttings directly in the bottle. When the gel is no longer liquid or goes gray, the product is not suitable for propagation.

Garden Safe Rooting Hormone powder doesn’t state an expiration date on the packaging, so this product doesn’t have a shelf life. However, the powder can go bad due to contamination with other chemicals or water. Also, you can dip the cutting directly into the container and remove the excess powder by tapping on the rim of the container.

However, I would still recommend transferring the amount you are planning to use into a sterile separate container, that way you will prolong the shelf life of the product and ensure that cuttings are not contaminated.

How long does it take for rooting hormone to work?

Gel rooting hormone tends to work in 1 to 2 weeks, so you will see the root development then. On the other hand, rooting hormone powder doesn’t claim to speed up the root formation, instead, it improves the rooting system overall and increases the chance of cuttings to actually root.

So, it tends to work in 3 to 4 weeks depending on the plant you are propagating. Check the cuttings for root growth weekly. If you can’t tell that cuttings have rooted, use my 3 go-to tips on how to find it out.

What is better – rooting hormone powder or gel?

Gel rooting hormone isn’t better or worse than powder, both have IBA as an active ingredient and long shelf life if stored properly. However, gel rooting hormone remains in contact with the stem after application, it seals the cut tissue, but rooting hormone powder is much cheaper.

So, if you are planning to propagate a lot of cuttings and don’t want to spend a fortune, rooting hormone powder can be a good option for you.

How to use a rooting powder:

  1. Take the cutting you would like to propagate and slightly moisten the end by dipping it in water.
  2. Dip the cutting end directly into the container and stir it in rooting hormone powder until it covers the bottom inch.
  3. Remove the excess of the rooting hormone powder – simply tap the cutting on the rim of the container.
  4. Place cutting into a hole in the pot with prepared potting mix.

How do you use a rooting gel:

  1. Take a sterilized shot glass and pour the amount of product you intend to use. Let the gel warm up to room temperature.
  2. Take the cutting and dip it to the gel to cover the end inch of the cutting.
  3. Insert the cutting into the hole in the pot with rooting medium.
Can you put rooting hormone on roots?

Due to its name, many growers assume that you can add some rooting powder in the soil to speed up the existing root growth. Although you can put rooting hormone on roots in the soil, it is unlikely to improve root growth.

That is because Auxins identify the injured part of the stem, for example, when you take a cutting, and program the cells around the injury to produce root growth. These undifferentiated cells are not produced without an injury and roots on their own are producing rooting hormones.

How to use rooting powder in water?

It is not recommended to use rooting powder in water when propagating plants because it is going to be diluted and won’t have any effect. When mixed with water it will go down the stem and wash off from the cut where it actually helps in root development.

However, for those who propagate cuttings in water, there is a liquid rooting hormone – Dip ‘N Grow Concentrate Rooting Solution. It comes with two active ingredients – IBA (1.0%) and NAA (0.5%). You would need to dilute the solution depending on the plants you are going to propagate.

For Hardwood cuttings you want to mix 2 parts Dip n’ Grow in 10 parts water. To propagate softwood cuttings you need 1 part Dip n’ Grow to 10 parts water. Dip each cutting into the solution for 5-10 seconds. Many growers have great results when using it for cuttings and growing them in soil.

Is rooting hormone safe?

Rooting hormone is safe to use to propagate cuttings as long as you apply it following the instructions. If we talk about the safety of the plant, some Auxins, for example, 2,4-D and 2,4,5-trichlorophenoxyacetic acid, are herbicides also known as weedkillers, so they target weed specifically without damaging other plants. As discussed above, synthetic Auxin in commercial rooting powders and gels is IBA which is a natural rooting hormone promoting root development.

However, it can be poisonous to humans if you don’t read the entire label before use. It can cause eye and skin irritation and if you breathe in the powder, it can cause upper respiratory tract irritation.

If you are not a fan of synthetic options, have a look at the natural solution and what common products that you have at home can help to growth healthy roots. Also, depending on the type of the plant, you can have greater chances to improve root growth if propagating cuttings in water.

Sources:

Kassahun, B. M., & Mekonnen, S. A. (2011). Effect of cutting position and rooting hormone on propagation ability of stevia (Stevia rebaudiana Bertoni). J. Plant. Biochem. Biotechnol6(1), 5-8. https://www.academia.edu/25118293/Effect_of_Cutting_Position_and_Rooting_Hormone_on_Propagation_Ability_of_Stevia_Stevia_rebaudiana_Bertoni

Paque, S., Weijers, D. Q&A: Auxin: the plant molecule that influences almost anything. BMC Biol 14, 67 (2016). https://doi.org/10.1186/s12915-016-0291-0

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