Rooting Hormones
Marijuana Horticulture
by Jorge Cervantes
Root-inducing hormones speed plant processes. When the stem of a cutting develops roots, it must transform from producing green stem cells to manifacturing undifferentiated cells and, finally, to fabricating root cells. Rooting hormones hasten growth of undifferentiated cells. Once undifferentiated, cells quickly transform into root cells.
Three substances that stimulate undifferentiated growth include napthalenaecetic acid (NAA), indolebutyric acid (IBA) and 2, 4-dichlorophenoxyacetic acid (2, 3 DPA). Commercial rooting hormones contain one, two, or all of the above synthetic ingredients and often include a fungicide to help prevent damping-off.
Rooting hormones are available in liquid, or powder form. liquid and gel types penetrate stems evenly and are the most versatile and consistent. Powdered rooting hormones adhere inconsistently to stems, penetrate poorly, spur uneven root growth, and yield a lower survival rate.
Liquid rooting hormones can be mixed in different concentrations. Always mix the most dilute concentration for softwood cuttings. Apply any rooting hormone containing IBA only once. If exceeded in concentration or duration, IBA applications impair root formation. As soon as cuttings are taken, clones start dispatching rooting hormones to the wound. They arrive in full force in about a week. The artificial rooting hormone fills the need until natural hormones take over.
Give cuttings a 5-15 second dip in concentrated solutions of IBA and NAA, 500-20,000 ppm. With a quick dip, stems evenly absorb the concentrated hormone.
Relatively new to the market, gels have caught on everywhere. They are easy to use and practical, but are not water soluble. Once applied, gels hold and stay with the stem longer than liquids or powders.
Rooting powders are a mixture of talc and IBA and / or NAA and are less expensive than liquids or gels. To use, roll the moistened end of your cutting in the powder. Apply a thick, even coat. To avoid contamination, pour a small amount into a separate container, and throw away any excess. Tap or scrape excess powder off the cutting; excess hormones can hinder root growth. Make a hole bigger than the stem in the rooting medium. If the hole is too small, the rooting powder get scraped off upon insertion.
You can also spray clones with a single foliar spray of dilute IBA (50-90 ppm). Be careful to spray just enough to cover leaves. Spray should not drip off leaves. An IBA overdose slows growth, makes leaves dwarf, and could even kill the clone.
Some growers soak their cuttings in a dilute solution (20-200 ppm IBA and/or NNA) for 24 hours. But I have seen few growers use this time-consuming technique.
To determine the rooting hormone concentration in parts per million, multiply the percentage listed by the manufacturer by 10,000. For example, a product with 0.9% IBA contain 9000 ppm IBA.
An all-natural, root-inducing substance is willow (tree) water. The substance in all willow trees that promotes rooting is unknown, but repeated experiments have proven willow water promotes about 20 percent more roots than plain water. This willow water is mixed with commercial rooting hormones for phenomenal results.
To make willow water rooting compound, find any willow tree and remove some of this year’s branches that are about one and a half inches in diameter. Remove the leaves, and cut the branches into one-inch lengths. Place one-inch willow sticks on end, so a lot of them fit in a water glass or quart jar. Fill the jar with water, and let it soak for 24 hours. After soaking, pour off the willow water, and use for rooting hormones. Soak the marijuana cones in the willow water for 24 hours, the plant in rooting medium,. If using a commercial liquid rooting hormone, substitute the willow water in place of regular water in the mix.