a-mused

To go along with jjeter's reply, I've found Kimura's technique for improving nebari to be rather excellent, perhaps a little more time consuming, but the results can't be argued with.

In a nutshell, the process is to expose the part of the nebari you want to get new roots on (or create an entirely new nebari!), use a 0.5mm drill (I use a 1/32" bit), and drill a small hole precisely where you want the new root to grow. Using a toothpick, apply the appropriate strength rooting hormone powder into the hole, then pack moist (not dripping wet!), long-fibered sphagnum moss around the site (I soak mine in water + superthrive - please no superthrive argument replies. I use and like it, you may not, and that's that.), and then apply soil to cover the moss. Watch your watering carefully so you don't accidentally create a wet, soggy mess of the moss but do manage to completely water the tree to keep the rest of the current root system happy.

If you're creating an entirely new nebari, you can also place a wire girdle somewhere between 1/4" and 1/2" below the new site/drill holes (I use 3mm aluminium or 10/12 gauge copper, whichever I grab first) and tighten the girdle until it bites fairly deeply into the trunk. Normally I'll girdle the trunk first to give me a guide as to where the holes should be placed vertically, relative to where I want the new nebari. I've done this with Hokkaido elms, cotoneaster, and dwarf pomegranates and it works very, very well. Just proceed slowly and make sure the girdle is parallel to the eventual soil line if you're changing the potting angle. Use appropriate protection when working with rooting hormone (surgical gloves or equal, a dust mask, and safety glasses are usually sufficient). When working with rooting hormone, I'll take a cleaned yogurt container (one with a plastic lid), place a small amount from the jar of powder and onto the lid for ease of application, and then dump whatever is left over into the yogurt cup, put the lid on it, and put it in the trash after I'm done - for safe disposal. This also ensures you don't accidentially contaminate your container of rooting hormone. For easy rooting species, normally 0.1% or 0.3% IBA works fine - you can find plenty of references to the appropriate strength for any given species using Google and various agricultural sites, like Cornell, etc. Once you start working with much stronger strenghts (up to 4.5% IBA if you're in the mood to root a 2x4!), just use more care in how you handle and store the stuff. Do keep in mind that stronger is not implicitly better. If you apply 4.5% IBA hormone to an easy rooting species that really needs just 0.3%, you're probably going to get some necrosis in the new roots - if they root at all. Most of the time, you're going to find the IBA strengths listed in "ppm" on many ag. sites (e.g. 2000ppm) - to convert this to a percentage, just lop off the last three digits and the rest is the percent (so 2000ppm is 0.2%, 8000ppm is 0.8%, etc).

Kind Regards,
-d