Hormone rooting compound
Hormone rooting compound (also known as rooting or hormone powder/gel) is a formulation of synthetic hormones which promote the growth of plant roots. They are used in plant propagation to encourage roots to grow from stem cuttings or layered stems.
The mix of hormone rooting compound is carefully devised as too much of a particular hormone (such as auxin) can inhibit growth. Different mixes are sometimes available for different types of cutting, eg a stronger mix for hardwood, weaker for semi-ripe and weakest for softwood cuttings, to allow for the different concentration of hormonal stimulus each requires. More often than not, however, they come in a single, multi-purpose formulation.
The compound can come in different forms, including powders and gels. Generally speaking a gel formulation is easier to use as it adheres to the stem more closely and, therefore, is less likely to be accidentally wiped off. Some also contain a fungicide to reduce the risk of the stem rotting.
To use the compound, tip a little of it into a small dish and dip the cut tip of the stem, or part to be layered, into the compound, tapping the stem afterwards to remove any excess compound. Throw away the compound in the dish – don’t put it back into the pot or it could contaminate the supply.
Check the label of your hormone rooting compound for the best storage method, which is often to keep it refrigerated. They usually last about a year, after which time their efficacy is reduced.