Deron Caplan
May 4, 2018
Vegetative propagation of cannabis by stem cuttings: effects of leaf number, cutting position, rooting hormone, and leaf tip removal
Best Way to Take Cannabis Cuttings
If you're cloning cannabis using stem cuttings, you’ve probably heard a lot of conflicting advice—how many leaves to leave on, whether to cut the leaf tips, and what kind of rooting hormone to use. This study took a scientific look at all of those factors to figure out what actually works.
What was tested:
Researchers took cannabis cuttings and tried different combinations of:
Number of leaves (2 vs. 3)
Whether leaf tips were trimmed
Position on the mother plant (apical/top vs. basal/bottom)
Type of rooting hormone (a synthetic IBA gel vs. a natural willow extract)
After 12 days in a controlled environment, they measured how many cuttings rooted and how good the roots were.
Key takeaways:
Use synthetic rooting hormone (IBA): Cuttings treated with IBA rooted twice as often and had better quality roots than those treated with willow extract.
Don’t trim the leaf tips: Cutting the tips of the leaves reduced rooting success without improving anything. If you need to reduce leaf area, just use fewer full leaves.
More leaves = better root quality: Three-leaf cuttings developed 15% better root systems than two-leaf ones. But both rooted at about the same rate.
Position on the plant doesn’t matter much: It didn’t matter whether the cutting came from the top or bottom of the mother plant—unless you trimmed the leaf tips. In that case, bottom cuttings performed worse, likely because they had smaller leaves to begin with.
Bottom line:
For better rooting when propagating cannabis:
Use three full, uncut leaves
Don’t trim the leaves
Use a synthetic IBA rooting hormone
Don ’t worry too much about where on the plant you take the cutting
If you need to reduce leaf area to fit more cuttings or manage humidity, it’s better to remove whole leaves than to snip off the tips.