Thanks Henry! This is a great article. One thing that I’ve questioned over the years was germination medium that is sold commercially. It is so fine and after seedlings germinate they seem to be stunted and yellow. It seems that there isn’t good aeration to the roots. I suspect the very fine size of this germination mix is just to get good soil to seed contact and is something left over from plug production where very fine particles are necessary to fall into the small plug holes.
This manscript looks at more mature plants and not seedlings and really seems to encourage us to have good aeration. It seems we can learn and apply a lot to our general rose growing. With the root tips I collect for chromosome counts I’ve really began to look more critically at root health and watering and aeration more than before as it is so important to get actively growing roots and then that translates eventually to good shoot growth.
Thanks again Henry,
In Robert Osborne’s book: Hardy Roses: An Organic Guide to Growing Frost and Disease Resistant Varieties, he describes how using a mixture of 1 part perlite to 1 part peat was disasterous for rooting cuttings. But using 4 parts perlite to 1 part peat work the best. He also noted that the cuttings would root in straight perlite but the roots would not survive transplanting. Maybe a 4 to 1 ratio would work better for starting seeds as well. I haven’t tried it, but it may be worth looking into.
If you try the link, type in perlite in the search box
and then select the reference on page 64, that will get the passage I’m referring to.
Thanks for the information Paul! Perlite and seeds reminds me of what Elton Strack used to use and taught me to use as a kid. He would take clear drinking cups he would poke holes in in the bottom. He would fill them with straight perlite to about an inch of the top, put seeds around the perimeter, and fill another half inch or so with perlite. It was fun to see the seeds germinate and then transplant them out. He had them close to each other around the perimeter. Over the years I’ve gone to baggies of peat instead just because I can accomodate more seeds easily this way and it is easier on the eyes to see a white radicle against the dark peat.
The straight perlite worked well for Elton. Jim Sproul has pictures of perlite with young seedlings growing and blooming. How do you do it Jim? Is there soil beneath, or straight perlite/
The link didn’t work at our library, but I found it by using google scholar and key words rosa rose root and bracketing the years of possible publication.
Evans, R.J., Hansen, J, Dodge, L.L., 2009, Growth of Rose roots and shoots is highly sensitive to anaerobic or hypoxic regions of container substrates, Scientia Horticulturae 119:286-291.