Hybridizing strategy question

I think I remember someone saying that it takes at least 100 attempts are needed to give a cross a good chance of producing at least 1 rose that has a lot of merit.

I am really planning on doing a lot of work next year and am wondering how to take that. Should I apply it to hips or plants. What I mean is, should I assume that 100 successful pollinations and the plants from those seeds would give me a good sample. I would assume that this could lead to more plants but in some situations, it might not.

Right now, I am thinking I may keep trying until a cross until I have evaluated 100 plants. I am not even sure that 100 is the number I should be using.

This is important to me because have a pretty defined end result that I am shooting for. Given that, I may want to repeat a cross several times until I have success or until I can come to the conclusion that the result that I am looking for is not going to be likely.

How do most the people here evaluate a cross and determine if it may produce some desired results? On average, how many pollinations do you attempt when trying a cross?

My intent is to keep good records through the years so I know what kind of offspring a given cross makes and if I reach 100 plants that I have evaluated without finding 1 with any redeeming qualities, I will give up on that cross and look for a different plan. If it


I once posted a message quoting what Ralph Moore once told me, saying that he believed that in a sample of 100 seedlings, you should get to see the full scope of what a cross will do. Of course, the number 100 is fairly arbitrary; if you have 90 seedlings you will still get a very good perspective of the value of a cross, and 200 seedlings will surely give you an exhaustive overview. Personally, I like to aim for 150 seedlings per cross.

The next question then becomes, how many pollinations were required to arrive at that ideal sample of 100 or more? Well, that depends a great deal on the plants you are working with. If you know that Seed Parent X produces full hips with many seeds, most of which germinate, then you can make relatively few pollinations and still arrive at your ideal sample. For me, roses like ‘Sequoia Ruby’ will give me a crop of 100 seedlings or more with as few as 20 pollinations. ‘Little Darling’ comes close to that rate as well, as does ‘Sequoia Gold’. Parents like ‘Abraham Darby’ are not so generous, requiring more like 40-50 pollinations to achieve a sample of 100 seedlings. Some parents that I work with are very hesitant to produce viable, easy-to-germinate seed and so, I have to make 1 pollination for every seedling I hope to get. Naturally, I avoid working with such reluctant parents unless they offer some very special opportunities for advancement of my work. ‘Muriel’ is one such rose. Its pollen will set seed only rarely and only on certain plants, and seed usually isn’t all that readily germinated. My guess is that the rate of success is about one seedling or less per pollination.

As for evaluating results, I believe that if you have a large sample of a cross (100 or more) and you do not see anything worthwhile in that sample, then you are not likely to see anything better by increasing the sample size, or repeating the cross the next year. If I get nothing I like from a cross in 100 seedlings, I won’t make the cross again, absolutely. If I did like what I saw, and if the scope of variety in the cross was very broad, I will undoubtedly make the cross again to have more opportunity to select something good. Two years ago I made a cross of ‘June Laver’ X ‘Out of Yesteryear’, and it resulted in over 70 seedlings, of which I kept about 20 for evaluation. Thats a very high percentage of keepers! In 2004, I narrowed that selection down to three seedlings, and next year I suspect one more will be eliminated. This year, I remade that cross to have a chance at finding something else I really like. The cross gave a very broad spectrum of variations, and so another sample would possibly reveal more than I saw the first time. In such a case, it is well worth repeating a good cross.

The bottom line: it helps to know how fertile your seed parents are. For me, it helps to do a preliminary test with a prospective parent before I attepmt any serious work with it. I make a few crosses, with anything I have that is a known fertile pollen donor, and I germinate them and evaluate. There are three things that I can determine in this initial assessment: 1) does the plant form seeds readily? 2) do the seeds germinate easily? and 3) is there anything of value in the test sample offspring? These three things can be determined in a test sample from an un-tested seed parent. If I have positive answers to all three questions, I will likely work with that rose in earnest the following year.

I hope that provides some kind of answer to your question.


I had one seedling that was a suprise this year. Nothing special, though. Ive been doing mass crossing with HC Anderson for the past 3 years. One of the germinations was a white/red picotee. Everything else was red…red…or red :slight_smile: Definately not OP either. The foliage definately has the pollen parent’s foliage and petal shapes (Ole).

Lesson learned: You really never know what is possible within a full run of crosses. Especially roses with unknown parentage variables. (ie HC Anderson is Montana x unknown).

Thak you Paul. Answers my question very well.

Interesting Jadae. I am hoping so some interesting variation. I plan on using a lot of Buck roses and it seems like some of them produce a good variation. Op folksinger seedlings that I raised had everything from single white flowers, single yellow flowers, double pink and double peach yellow blends. The only problem is that they are all mildew prone. Folksinger is winter hardy though. Need to cross it with mildew resistant roses.

Luckly I have so much mildew in my garden, its easy to test roses for mildew :slight_smile:.

Sometimes that curse is a blessing. Black spot for my area. I got my friend (a dual major in Crops and Botany) hooked on breeding. He is putting Rosa foetida bicolor in his rose bed on purpose just due to what you stated. The horticulture part of me wanted to object (bad aesthetics! put it out to pasture) but I understood why he is doing it.

Mildew with seedlings this year (for me,oddly) was quite bad. Every year it’s something new I tell ya. I cant wait to see all of your discoveries, though. It is a really fun process.

Hi Steve:

Selecting fertile seed parents is the most important step. Several of the ones that Paul mentioned would be a great place to start. Also, when you do start producing seedlings, you will find that many of your own seedlings will set hips better than most commercial varieties. This is because most commercial varieties have been selected for their ability to bloom, NOT for their ability to set hips. Many roses stop bloom production once a large crop of hips begin forming.

So, keep an eye out for good hip setter among your seedlings. Of course you want to select good hip setter seedlings that have desirable qualities!

Then, as mentioned above, you need to assess germination rate of the good hip setters.

Once it has been established that a particular variety sets hips well and germinates well, I will try a wide range of pollens on it (ones that have worked well for me in other crosses). At this stage, I am only looking for a handful of seedlings from each cross. Then, these are evaluated for desirability. Those crosses that produced a larger number of clean, desirable seedlings are repeated the following year to a much greater extent.

Using good hip setters/germinators will advance your work much faster.

Jim Sproul

Steven ,It is very easy to cross a rose , but you only have one chance in 4,ooo,ooo of breeding what you want.

you would be best to know who your mother plants are then do 100 crosses per day for 100 days plant the whole lot and leave it in the lap of the gods , good luck .


Be encouraged that about 1 seedling out of 100 is worth keeping or giving away (depending on the cross). While 1 seedling out of 1,000 may have some commercial potential. The “odds” are not that bad.

Getting that number of seedlings (1,000) is just easier using reliable hip setters/germinators.

Best wishes to you!

Jim Sproul