Understanding that “good roots lead to good plants”, many folks are interested in ways to stimulate plants into growing more roots, more quickly. There are three, general ways that additives can do that, through the use of synthetic rooting hormones, the application of large doses of some trace elements that stimulate the production of natural hormones, and the application of naturally-sourced phytochemicals from kelp extracts.
As plants grow, the vegetative (shoot) apical meristem cells secrete auxins that move down through the vascular system and stimulate the growth of roots. As the root apical meristem cells grow, they secrete cytokinins that move up the vasculum and stimulate vegetative growth.
Synthetic hormones are simply analogs of the natural hormones produced by plants. Commonly-used products containing sythetic hormones include K-L-N and Superthrive. They can be quite effective at stimulating root and plant growth, but have some potential pitfalls. First of all, they are chemically unstable, losing all potency relatively quickly if allowed to get warm or are exposed to sunlight. Second, they can be overused, which can lead to flower deformities or stunted growth. In extreme cases, they can be fatal; the herbicide 2,4-D is a synthetic auxin that overstimulates plants to death.
Mega-Doses of Trace Elements, specifically boron (B) and molybdenum (Mo), cause the plants to accelerate their normal rates of hormone production, significantly stimulating root growth. Mega Thrive falls in this category. Like synthetic hormones, such applications can easily be overdone leading to plant death, buth there is a more insidious issue with their use: immediately upon application, the treated plants become toxic to birds and mammals, so they should only be used to rescue particularly valuable plants to which pets and grandkids will never be exposed.
Kelp Extracts can work in a number of ways, but they are highly variable in their activity and potency, depending upon the species of kelp used and how it has been processed. Our article, Comparing Kelp Extracts, explains that in more detail. Many are so over-processed, especially if dried, that they are rendered to be nothing more than mineral nutrients – fertilizers. Some may contain traces of natural hormones, but often, those are higher in cytokinins than auxins, so can lead to “leggy” growth. Kelpak is unique, because its potency comes from a wide array of natural phytochemicals and not just due to hormones. I like to refer to it as a “Plant IV” – just as a football player may get a transfusion of glucose and electrolytes at halftime so he will have the energy to play better in the second half, the application of Kelpak gives plants large doses of the same phytochemicals they make for themselves, but by being sourced externally, they don’t have to expends their own resources to produce thenm, giving them more energy for better growth.