I’m looking for comments on my ‘experiment’ design.


There’s been on various forums a lot of back and

forth regarding ‘paper towel’ vs. ‘sphagnum moss’

as a stratifying medium. In the Rugosa article Henry

kindly provided a link to it mentions activated charcoal

as a good germinating medium. However the charcoal reference was from '83 and other articles since then (non-rose seeds) have seen no benefit greater than sphagnum moss.

(Or seen a benefit of smoke rather than charcoal).

So I’ve decided to try to determine if I can find any difference. Someone has nicely send me a large number of hips, which I’m processing through. After a Bromelain soak, I’m going to divide the seeds into different categories:

Paper towel

Paper towel and charcoal

Sphagnum moss

Sphagnum moss and charcoal

If I have enough seeds of a given variety, I may further have replicates of each category, and I may split the Paper towel (which might be a coffee filter instead of a paper towel) category int paper towel and paper towel with mold suppression (e.g. that I would treat the seeds if they started showing significant amounts of mold). I won’t be able to do any real statistical analysis, but maybe I can prove if there’s any gross differences. I view the plain paper towel as my ‘control’.

Any thoughts or comments from you true scientists out there?

Chris Mauchline

Chris, I’ll be looking forward to your results.

I’ve done a little experiment as well this year, and that is, cleaning seeds with Comet cleanser (1/2 hour in a concentrated paste) vs 24 hour peroxide soak. Surprisingly, the Comet batch is germinating much better than the peroxide batch. All seeds are from Scarlet Knight. Not a good scientific design since there are twice the # of seeds in the peroxide batch, but you can see there’s quite a difference. So far:

Germinations so far:

5 out of 200 in the peroxide batch (and 3 died)

14 out of 100 in the Comet batch (only 1 died)

I tied using charcoal and was disappointed. I wonder if the size of the charcoal particles has an affect. I used fine dust like charcoal from a health food store.

Regarding the media used, I suggest a sand one be included in the test.

From memory: I think David Zlesak has reported some negative results regarding using hydrogen peroxide “soaks” to increase germination in a Rose Hybridizer’s Newsletter.

The idea of charcoal is to bind up the growth inhibitors. And it isn’t something that mold can grow on. Paper towels are essentially sterile as they come, but easily get contaminated from your hands or other stuff and mold grows pretty well on damp paper. Peat moss is acidic enough and has a lot of humic acid so most molds cannot grow in it. And it tends to inhibit those growing on the seed. Ground sphagnum is not the same thing. It is more like living moss and will not be so inhibitory of molds. I’ve germinated a lot of seeds (not roses) on paper towels and they do fine, but only in short term tests. If a few seeds are non-viable and rot they spoil the whole batch sometimes. That’s why I use only peatmoss. With the roses I’m using germination is fairly good. Charcoal might help for those that are strongly inhibited- at least that’s the theory. I would not use briquets but the kind made for fishtank filters. Never have tried health food store material, I found enough old “activated charcoal” from coconut hulls at work to last me a lifetime.

I looked back on that article where I compared hydrogen peroxide versus water soaks before germination and found that the 1% and 3% H2O2 soaks led to about half the germination as the controls. Also some seedlings with the 3% had stunted radicles. My thought was that if oxygen was limiting as H2O2 forms water and oxygen gas it might be helpful to germination.

When I worked at the Forest Service with tissue culture of white pine trees after a 2 week duration of embryos in culture with the hormone cytokinin we put them on media with activated charcoal (3 weeks). That was done to bind up the cytokinin and stop adventitious shoot formation and promote shoot elongation. The activated charcoal seemed to promote chlorosis pretty readily and stunted growth. It probably not only bound up hormones, but other substances necessary for growth as well. Perhaps the pH in the media was altered too?? I pH’d the media before adding the activated charcoal because it would clog up the pH probe.



David, that’s a very interesting experiment, expecially since peroxide soaks are often recommended. Does anyone have any additional comments on this? I’ve had stunted radicals in some of my batches but have not done any comparative studies. Others have noted (non-scientifically) that H2O2 sometimes seems to stimulate germination. I would love to see more discussion on this.

By the way, I will try the experiment I did above comparing comet cleanser and H2O2 soaks and will also use a water soak control and an oxyclean soak. Will report back later.


I also have a water soak vs. Oxyclean soak experiment running (treatment on 15 october). I use Bonica seeds. At this moment most of the Oxyclean treated seeds are opening, the water treated seeds are lagging behind. But I’m interested in differences in viability, because in the Oxyclean batch some seeds look black inside. Will let you know how it turns out.


Rob, that’s an experiment for which I’ll be anxiously awaiting your results! In my experience with Oxyclean, the seed coat becomes somewhat transparent allowing you to see which seeds have dead (black) embryos inside. How long did you soak the seeds in the Oxyclean?

Judith, I first soaked the seeds in water for about 18 hours, and then did the Oxyclean soak for 18 hours (and put the control group seeds in fresh water). I also noticed the transparency. I don’t know yet if the Oxyclean is killing the embryos or that they were dead before the soak and the Oxyclean just made it visible.

Rob, if the 18 hour soak revealed black embryos, I’m fairly convinced they were dead to begin with because I highly doubt that they would turn black in 18 hours, especially since the oxy tends to have a bleaching affect. As I noted in another post however, a soak in oxy that is too long (like several days) definitely stops germination, but I don’t know if it actually kills the embryos in that case. I’ve had germinations in oxy-soaked seeds in the past.

I couldn’t find any posts here that discussed the following paper so here it is:

Levels of endogenous abscissis acid in rose achenes and leaching with activated charcoal to improve seed germination.

Yambe Y, Hori Y. and Takeno K, J. Japan. Hort. Sci. 61 (2) (382-387)1992.

Link: rms1.agsearch.agropedia.affrc.go.jp/contents/JASI/pdf/society/47-2207.pdf