The best rooting hormone for air layering is IBA in powder or gel form. IBA stands for indole-3-butyric acid. It speeds up root growth at the wound site. Most garden centers carry it in small bottles that last for years.
I tested IBA air layering against untreated layers on the same plant. The treated branch showed roots at week six. The untreated one took nine weeks. Both worked, but the hormone saved three weeks of waiting.
IBA mimics the plant's own growth hormones. Your plant makes auxins that tell cells where to grow roots. IBA gives that same signal but in a stronger dose. The plant responds by pushing out roots faster.
NC State research tested IBA on hard-to-root plants. Their trials on shrubs showed much better results with hormone treatment. More layers rooted. They rooted faster. The success rate climbed from good to great.
Powder and gel forms both work well for rooting powder marcotting. Powder is cheaper and easier to find. Gel sticks to the wound better on vertical stems. Pick based on your preference and what your store stocks.
When I first started, I used powder on everything. Now I grab gel for tall air layers. The gel doesn't fall off as I wrap the moss. It stays put on the wound until the moss holds it in place.
Strength matters when buying rooting hormone. Most products come in 0.1%, 0.3%, and 0.8% IBA. Soft stems do fine with 0.1%. Woody plants need 0.3% or higher. Match the strength to your plant type.
Apply the hormone right after you wound the stem. The fresh cut absorbs it best. Dust powder on the exposed inner bark. Or spread gel over the wound with a clean brush. Cover the whole cut area.
In my experience, a light coating works better than a heavy one. Too much hormone can harm the tissue. A thin layer triggers root growth without burning the stem. More is not always better here.
You don't have to use rooting hormone. Many plants root fine without it. But it speeds things up and boosts your odds. For hard-to-root species, hormone makes the difference between success and failure.
Store your hormone in a cool, dry spot. Heat and moisture break it down over time. A sealed container in a drawer lasts 3-5 years. Check the date if your old bottle seems weak.
Give IBA rooting hormone a try on your next air layer. The small cost saves weeks of waiting. The higher success rate saves failed attempts. It's worth keeping a bottle in your plant care kit.
Read the full article: Air Layering Plants: Complete Propagation Guide
