Thank You Brent.Irene
I'm probably not the best person to answer this. My success with 'Shimpaku' cuttings has been hit or miss. Some years I get almost 100% take and other years less than 5%. The standard procedure is to take cuttings of new growth with just a bit of brown wood at the bottom. Cuttings are taken in March and are usually rooted by mid summer. Bottom heat is not necessary but will speed rooting. Hormone level doesn't seem to be too critical. I have used everything from 0.3% IBA to 1.8% IBA. The higher levels will 'burn' the base of the cuttings, so if you use higher levels, dip only about 1/4 inch of the stem into the powder. Physiological conditions seem to be a great factor, but I am still trying to determine what they are. Usually this implies an important carbon/nitrogen ratio. Cuttings from weak, underfed plants have given me poor results, but overly nitrolized fast growing shoots don't do that well either, although greener shoots (more juvenile) cuttings appear to show less necrosis from the IBA. Medium may also be a factor. I have always used a perlite or bark/perlite mix, but some of the best cuttings I have seen come from sand.