As is true about anything that I write related to rose breeding, this article is NON-science, but hopefully it is not nonsense. Nevertheless, I will begin with a disclaimer. The following ideas or recommendations reflect my own experience. Many of the ideas are not my own, but are a collection of thoughts and opinions of others. They are ideas that I have tried over the years, and I have found them useful.
So, here is what goes on in my rose garden during the months of autumn....
Perhaps one of the most important tasks during this time is to carefully observe the rose garden for new parent roses - especially new "mothers", or seed parents. When I first started breeding roses, the new seed parents were always commercial varieties. Every spring, I would buy all of the new popular roses and wait until fall to see if they would set hips. The hip setters would become my new seed parents. Now, most of my new seed parents are selected from my own seedlings. The nice thing about using your own seedlings, is that they are your very own "secret" ingredients and they represent approximations of your own rose breeding goals. Using them as seed parents will take you one step closer to your ultimate goal to develop something new and completely unique. This then, is the final evaluation characteristic (observing for hip formation) of the seedling bed that I make, to find new parents to carry the work further down the line. Certainly, desirable non-hip forming seedlings should be considered for further use as pollen parents.
Of course, the next thing to do is to collect the ripening hips. This is the great harvest that we all look forward to each fall. It is especially exciting to see healthy large hips of your most anticipated crosses turning a rich orange or yellow color. Hips can be harvested at any time after they begin to show color. At the end of the season, to simplify the process, I pick all hips of a particular variety when most of the hips are showing good color. Even those that have not changed color are picked. This is done to save time (rather than having to go back and locate storage bags of crosses that have already been picked each time you decide to go out and pick newly ripening hips). I have separately planted the less ripe (green) hips and have found germination to be very poor - though with an occasional cross, germination may not be that bad. For those who have made fewer crosses, or for those difficult crosses, if frost is still a way off, you should wait as long as you can to harvest the hips to hopefully improve viability.
The hips are then stored in ziplock bags until I am ready to begin shelling them. Because shelling the seeds is the most loathsome part of this hobby, I am sometimes slow to get started on it. A method for seed extraction that can really help to speed up the process is to use a regular kitchen blender. The blender is half-filled with water and turn on to medium speed, then several hips are dropped in. The turning blades easily chop through the hip pulp, but do not destroy the seeds (at least in theory). After about 1:15 to1:30 minutes:seconds, the blender is turned off. The chopped up pulp can then be washed away from the seeds by using a strainer.
Though using a blender is a much quicker method to move the seeds, I do not recommend this method. Those varieties that have more durable seed coats, may largely tolerate the abuse, however, I have repeatedly tested this method and found that it definitely adversely effects germination, even when the seeds appear normal. Therefore, I have gone back to removing the seeds completely by hand. It takes me about one hour to remove 500 seeds. My average annual harvest produces 20,000 to 40,000 seeds. That means that I spend on average, 40 to 80 hours each year on this task that I despise so much. The effort though, is well worth the increased germination. Who knows, by carefully removing the seeds from the hips, you may very well save your very best seedling.
As the seeds are removed from the hips, data are recorded: the particular cross, number of hips for that cross, number of seeds for that cross. These data will later be transferred to an Exel spread sheet (Still later, germination data will be added, which will allow a detailed analysis of germination rates. This information will be used to guide decision making to select future crosses.)
Extracted seeds are then wrapped in a paper towel (I use Brawny®). The wrapped paper towel is then dunked into a Captan solution (made by mixing about 1 to 2 tablespoons of Captan in 1 quart of water). Excess solution is then squeezed out and the moistened paper towel containing the seeds is returned to the ziplock bag that was used to store the hips of that cross.
It is important to make sure that seeds are stored in a moistened condition. I have tried to store the seeds dried for several weeks before dipping them into the Captan solution, but ended up with a much reduced germination rate.
The ziplock bags, containing the seeds, wrapped in moistened paper towels, are then placed in the refrigerator for 6 to 10 weeks. This cold period is important to simulate winter which is needed to improve germination. At the end of the cold treatment period, the seeds are planted. This process will be described in more detail in the next installment.
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