Five years ago I posted the results from an experiment that measured the effectiveness of different approaches to rooting seedling-cuttings (see “Effect of hormone treatments” for details).
The study had been on my mind ever since as I’ve been curious about whether increased exposure to rooting hormones makes a difference. This spring, I decided to find out.
Instead of taking an academic approach like I did five years ago, I followed a more-or-less consistent protocol and took some notes. I used Dip-N-Grow liquid rooting hormone for all of the cuttings, but I varied the dilution and duration.
I hadn’t planned to share the results until a very clear pattern emerged. Can you spot it?
Japanese black pine seedling-cuttings
10x dilution @ 5 min.
10x @ 5 min.
Row 1 (5x @ 1min.)
Row 2 (5x @ 2min.)
Row 3 (5x @ 5min.)
Rows 4-7 (5x @20min.)
5x @ 20 min.
Here are the numbers.
Flat 1 (10x @ 5 min.): 55/77 (71%)
Flat 2 (10x @ 5 min.): 50/77 (65%)
Flat 3 (5x @ 1 min.): 11/11 (100%)
Flat 3 (5x @ 2 min.): 11/11 (100%)
Flat 3 (5x @ 5 min.): 10/11 (91%)
Flat 3 (5x @ 20 min.): 20/44 (45%)
Flat 4 (5x @ 20 min.): 24/77 (31%)
What struck me was that almost every seedling-cutting lived when the concentration was 5x and the exposure was under five minutes. Anything more than that and the numbers dropped significantly. If I try this experiment again, I’ll be looking at variations in the neighborhood of 5x @ 1-5 min.
Taking a step back from the data, I’m actually surprised any of the cuttings lived this year. When I keep seedling-cuttings outdoors and don’t move them into the sun until they show signs of growth, I find nearly 100% take.
This year I was less careful. The cuttings were exposed to full sun without water the day after they were planted. Then, after a few days in the shade, I moved them to a spot where they got morning sun. They quickly dried out again so I moved them under shade cloth for a few weeks before bringing them back into a location with morning sun.
For the highest success rate and the best roots, I’d recommend keeping the seedlings in a greenhouse with misters and bottom heat. Instead, I wanted to see what the results would be taking an approach that’s available to anyone with both sun and shade in their garden. The dryness and early sun exposure was accidental – and definitely not recommended!
I don’t know what the roots look like yet, but if I find any differences among the above groups, I’ll be sure to post the results.
Healthy seedling-cuttings
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The home of Chris and Lisa Kirk and their beautiful bonsai nursery was lost to fire this week in Oregon. You can help Chris and Lisa, as well as Telperion’s caretaker Roxie Eslick, by contributing to their Go Fund Me pages.
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