How much realty per new seedling?

I am wondering how much realty folks feel is appropriate for each baby to give an honest and fair appraisal early on as to a seedling’s future value.

When I prick my germinating seedlings from the ziplock bag in which I stratify, I typically start them off at about 5 seedlings per 4 inch pot, on the assumption that the weaker plants will be culled pretty quickly allowing the stronger ones to grow on.

What in fact tends to happen is two-fold. 1. The more aggressive often don’t give the others a fighting chance to show what they can do, which I used to believe was a good culling practice, but the weaklings are lost without any evaluation of their potential, and sometimes a more demure plant might have better architecture ultimately. 2. When seedlings of equal vigor are in the same pot, they all suffer equally, and I wonder if I am not consequently unjustly underwhelmed by the entire lot of a given pot.

I am particularly interested in the opinions of those who have successfully selected and marketed their progeny, if any are available to chime in. (I mean, my technique kinda works, but it is way less than ideal…)

I am also curious as to how many seedling most of your germinate in a given year. (I don’t know how an amateur breeder with a modest homestead can give a fair shake to the seeds they cross in any given year.)


Thank you for this highly interesting question.

I have not yet launched a rose into the market, but my opinion may still be of interest. I now follow the same principle as you. In the past, when the number of seedlings were on a smaller scale, I was always willing to give the supposedly weaker seedlings a chance, especially if they seemed somehow interesting. Unfortunately, it turned out for me that a weak seedling with growth difficulties will remain a weak seedling with various problems, susceptibility to disease, etc., in the future. Too many genetic inhibitors prevent a vigorous development. Separation and a special care management had not helped either. This realization has taught me that promoting feeble seedlings is mostly not really worth the effort.
I also consider the percentage of those that would have developed into a strong and healthy plant to be very small.

It will indeed be exciting to see how the professionals deal with this issue.

Roseus, do you then separate seedling of equal vigor to give them equal opportunuty to show their stuff?

And when i refer to the less vigorous seedlings, I am not talking about things that need life support, but I suspect that roses like the popular “Scentuous” or even Kim’s own “Annie Laurie McDowell” might not have had a fair shake if potted with genuinely aggressive seedlings. (Feel free to tell me that I know not of what I speak, Kim!) There has been a movement towards more demure “patio roses” for a couple decades at least, and “aggressive growth” might not be a stellar metric by which to judge, it seems. (I am presuming, and don’t pretend to know.)

I expect I will have several hundred successful germinations this yea, if past rates are any indication, and want to be able to determine which are really worth keeping beyond the usual Darwinian battles in my gardening hellscape. (My preconcieved notions about which seedlings I think should be valuable based on the efforts it took to create, or my blind prejudices, have no doubt influenced the extent to which I might attempt to sway survivability in the past. That is human nature. But it no doubt results in a fair number of “best” seedlings going to compost.)

How best to cull older seedlings is a similar topic, albeit for another thread. Based on my goals, I thought garden performance in TX would certainly be an effective means, but I have been likewise embarassingly slow to realize that releasing the equivalent of juvenile kittens to fend for themselves in the Serengheti serves little profit. I have lost a good many otherwise nice seedlings that way.


Yes, with seedlings from special crosses that are more important to me and that I consider particularly interesting, I take out the competitive pressure of the stronger seedlings by planting the weaker ones together. A separate selection is better possible in this way, too. By ‘vigorous development’ I don’t mean ‘aggressive growth’, I mean just a solid growth habit that involves continuous development from leaf to leaf and so on with an adaptable and suitable root system. In weaker seedlings, this fluently development is slowed down, resulting in large temporal gaps between the individual stages. Even, the corresponding root system is therefore mostly weakly developed . Malformations may also occur. Then the moment has come for me to realize that there is no point in continuing to grow such seedlings.


I haven’t commercially introduced any roses yet, either. I use your method as well, although I try to use cell packs for seedlings if I have them. Competition for light and space is no better, but the seedlings are more easily separated for repotting, and at least they don’t share the same root resources. If any seedlings are excessively vigorous but seem valuable or promising, I’ll separate them from the rest into larger containers as needed, time and space permitting. For any especially promising-looking seedlings regardless of vigor, I’ll still separate them if the trays are becoming too crowded. Sometimes I switch seedlings around among cell packs (once they’re sufficiently well-rooted) in order to make sure that seedlings are more evenly matched within each pack.

Sometimes I will take a more extreme approach and cut back certain especially vigorous seedlings that get too big, usually only if I’ve already seen a first bloom (generally one that didn’t knock my socks off), or if the seedlings are likely to be once-blooming anyway (assuming I was expecting and planning for once-blooming behavior). Cutting back can also help them to survive a little longer if they are using water faster than I can provide it and I don’t have time or space to repot.

I do also pot up multiple seedlings into shared single containers, especially if I run out of cell packs or if I already have lower expectations of a cross overall, or if I expect that I can make early cull decisions, and/or if I have really high seedling numbers and am running low on space. The combination of transplanting, switching around, culling, and cutting back different individuals usually lets me keep most of the worthy seedlings alive and reasonably healthy.

Limited indoor space is another reason why I’ve begun delaying stratification of my seeds more as time goes by–my hope is that some of the vigorous early seedlings can be moved safely outdoors rather than needing special measures inside, and that should leave more light space for the slower growers and later germinators. The downside is that I end up with more seedlings sprouting after the weather outside is already hot. I also keep my best seedlings inside longer, which further limits available space. Last season I had hundreds of rose seedlings (plus seedlings from crosses in other genera), but this summer I made fewer pollinations. In addition to other kinds of plants and seedlings besides roses that need the same indoor real estate, I also ty to propagate my most promising seedlings early, even before moving the original outside. It’s a way of hedging my bets against sudden, unexpected loss due to RRD, animals, etc.



I plant my seeds in seedling benches and vary the closeness of the seeds depending on historical germination rates for each seed parent. The goal is to not waste space, but also to provide sufficient space to allow adequate growth. Seeds from seed parents that have lower germination rates are planted more densely.

I try not to worry too much about individual seedlings now since from experience only one or two seedlings out of about one hundred are worth watching. Even so it is clear that later germinating seedlings when in close proximity to older more vigorous seedlings will be handicapped in their growth and may never get the chance to show their stuff. So in the end, I think we all just need to grow as many seedlings as we have time for and to try to give them the best possibility for survival.

For the unculled seedlings that make it to the end of the year, I will typically plant 3-5 together into larger pots for further evaluation outside the greenhouse. Sometimes after another growing season I’ll find that one of these (previously not vigorous seedlings) will finally show what it can do and shines above the others in the pot.

There can be many reasons why young seedlings don’t compete well…

Jim Sproul

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