You know you're supposed to stop, or drastically cut back, fertilizing your plants between September and March to aid in their necessary dormant period. But, did you know you can work on root health all year long? Because root stimulators are a hormone that encourages root growth, rather than a chemical that forces plant growth, you can help your root structure become sturdier and ready for the coming season of above-ground leafing, blooming, and fruiting.
What is root stimulator? It sounds like a fertilizer but isn't quite the same. It's a hormone (auxin) that is produced by young plants when they are forming their root systems. Indole Acetic Acid (IAA) is the naturally occurring form of auxin found in plants. Indole-3-Butyric Acid (IBA), which is synthesized IAA, is the active ingredient you'll see on the labels of commercial root stimulators.
Why not fertilize your plants all year long? Fertilizers are great during the growing season, but now that it's winter and plants aren't photosynthesizing and blooming, they don't need fertilizer. In fact, overuse of fertilizer in the winter can cause more harm than no fertilizer at all. The plants don't have a use for the nutrients and so they don't absorb them into their roots. These fertilizer chemicals build up in the soil and cause root burn, overall weakness, leaf burn, and possibly death of the plant.
IBA drives lateral root development. We think about deep, vertical roots being the most important structural aspect but although roots are underground, it's critical they have oxygen for plant health. Most oxygen in the soil is found closer to the surface so a greater quantity of lateral roots can seek out and absorb these tiny pockets of oxygen. Plants struggle to develop healthy root systems in compacted or poor soil. This goes for both huge trees outside and tiny indoor begonias in pots! When we plant trees, shrubs, and perennials, we include a dose of root stimulator to counteract transplant shock. There's no reason not to give your newly potted houseplants a little help too! The healthier the root structure, the more dynamically your plant will grow.