Rooting hormones used in the nursery industry are synthetic versions of
naturally occurring plant compounds called auxins. The two forms most commonly sold
are usually listed as IBA and NAA.
Hormones are needed by plants in very small quantities so they are sold in ready to use or
ready to be diluted formulations mixed with something else. The most common forms
are either mixed with talc and come in a powder form or can be purchased as a liquid
either diluted in alcohol or water. There are plants that seem to root more successfully
when powders or alcohol based or water based liquid solvents are used but toxicity from
solvents is rare and almost always occurs when alcohol is the solvent used. Most of the
time, any of the solvents can be used with the crop you wish to propagate.
The reasons hormones are used when stem rooting cuttings are: 1) to make rooting
possible when too little natural hormone exists, 2) to increase the percentage of rooting,
3) to increase the number of roots per cutting and 4) to have cuttings root more rapidly
and thereby shorten the length of time you need to keep your stem cutting alive before it
can support itself.
Research has shown that if you apply too high a concentration of hormone, it can be as
bad as not using any hormone at all. Stem tissue can be killed by too much hormone or
using the wrong form of rooting compound. The end of the stem will often turn black
when this happens and, if there is any rooting, it takes place above the dead, black stems.
(This blackened end of the stem can also happen when the bottom of the cutting is too
wet.) Too high a hormone concentration has also been implicated in keeping plants from
ever breaking buds and growing so they root but never grow new shoots again.
Therefore, it is important to use the lowest concentration of rooting hormones that will
give you the maximum percentage rooting and number of roots per cutting. Lists of
suggested levels of rooting hormones can be found in the listed reference books. These
books will also tell whether other propagators have had more success using NAA or IBA
or a combination of the two and whether the success was with a powder or liquid
formulation and often which formulation worked best.
Rooting hormones should always be applied to a freshly cut stem so you will either need
to hormone treat when you are collecting cuttings from stock plants or re-cut when
preparing cuttings for sticking. Rooting hormones are much more readily absorbed
before plants begin to scab over or heal a cut. In addition, for many woody plants, a
liquid formulation has been successful at a much lower concentration than a powder
formulation. For example, 2500 ppm IBA in a liquid has shown similar or better results
than an 8000-ppm powder when both hormone formulations produced good quality
rooted cuttings.
Powders are usually best used as they come from the manufacturer. Remove the amount
you expect to use then seal the container and put it away. Do not stick cuttings directly
into the container as you may contaminate it with microbes that can reduce the
effectiveness of the powder within the container. For the same reason, do not return
unused rooting powders to their original container.
Liquid formulations often arrive in a concentrated form that needs dilution. Suggestions
in reference books may be for 2500 ppm, 5,000 ppm or 10,000 ppm but the label lists the
active ingredients in percentages. 1% is equal to 10,000 ppm. Therefore, if you need
2500 ppm, use 1/4 of your 1% solution and 3/4 of whatever you are using to dilute which
is often water. 2500 ppm is 0.25 or 1/4 percent. 5000 ppm is 0.5 or 1/2 percent.
Again, for sanitation purposes, only prepare as much rooting solution as you need. Never
stick cuttings into the original container and do not return unused dilute rooting solution
to the original container.
Rooting hormones last longest if they are kept in their original containers and stored at
room temperature or under refrigeration. Keep them out of direct sunlight and heat when
storing them and they can remain effective for years.
Some Commercially Available Rooting Compounds*
Product Name % Active Ingredient Liquid or Powder
C – Mone 1.0 to 2.0 IBA Liquid
C – Mone K 1.0 IBA Liquid
C-Mone Plus 1.0 IBA plus
0.5 NAA
Liquid
Dip n Grow 1.0 IBA plus
0.5 NAA
Liquid
Woods Rooting Compound 1.0 IBA plus
0.54 NAA
Liquid
Hormex 0.1 to 4.5 IBA Powder
Hormodin 0.1 to 0.8 IBA Powder
Hormo-Root 0.1 to 2.0 IBA plus
15% Thiram
Powder
*Adapted from NC Agricultural Chemicals Manual
Anyway... I went ahead and used the "clonex".
and as far as the price, I think $20 is worth it for a bottle that lasts a year, depending I guess, for something that works so good.
