1st Green of 2024 - Two Step conditioning Before Ambient

Hi Stefan,

Txs for the feedback and experiences. l intend to use them for crossing if still around when they decide to bloom.

Margit maybe preoccupied, so what l think l know of the mother plant has been relayed to me, (never seen it) in that the seeds are from the most eye pleasing bush in an academic botanical garden collection.

There are apparently 3 bushes. And in terms of better science clarity, there is a shrub of Rosa laxa Retzius nearby that has canes that have penetrated into the R. berggeriana mother bush drip line. Not a root stock laxa. The risk, or benefit depending on your view, is obvious to me, a higher potential for cross pollination opportunities (what the talls and/or big leaf shorty seedling may owe to their height and /or leaf size ? … pure 13 week old conjecture for now).

Hardening off of the seedlings has been noted as likely going to have to be done in small progressives steps - based observations that in the less than 3 hours out of their incubation chamber youngest leaves showed pronounced wilting and shrivelling. Very humid in container and on purpose.

No sprays have been used over the last ~ 70-90 days. Only the “mosquito larvae” terminating “organic” fungus gnat pesticide granules and yellow sticky tape. Speaking of which replacing the original Cadillac ace granules has been a challenge - newer version not up to scratch - lower dose likely.

I have been pleased the seedlings have not been attacked (immune by hard climate? genetic selection?excess humidity?) by botyris, pm or spider mites which have been, and still are, ongoing issues depending on location on the time spectrum for the indoor season duration. These have plagued their neighbouring enclosed heated container of cuttings from various roses, and my own crosses that are in an open holder.

Though the plagues are declining in viciousness in latter roses as the days lengthen out. I have noted new healthier leaf node growth on the crosses (coming out of dormancy?).

End result for me? May finally have the white version of beggeriana that is speculated to be the cause of why a small flowered (but very tall) rambler thrives down to Zone 2 (the Polstjarnan ?cross? from Finland hybridized by Wasast-Järnan, in 1937).

And it took less than 100 years, and only slightly longer than for the obtaining of R laxa by me to at least acquire known building blocks for potentially hybridizing cane hardy Arctic ramblers/climbers/roses.

Good on the prairie pioneer hardy hydbridizers who succeed in a much smaller world of options.
:slight_smile:

P.S,

Forgot to mention, at my hobbyist collector’s rep peril, to credit and name drop, that got lucky and received a clone from the original Ross Rambler mother plant that was in the good doctor’s garden … another parent producing bone hardy roses (laxa I believe) … availability of raw material excuses gone, … except for my hybridizing skills may need severe burnishing up.

Now that you mention it, those seedlings do show a lot of variation, and probably include some hybrids. It might be handy to have some diversity to start with. I wonder if rootstock “laxa” (R. caesia) would even be wood-hardy there, but it would be interesting to see a hybrid with true R. laxa. The seedling on the right in your lineup does almost give that impression.

The humid isolation tent might just be your best friend–I don’t doubt that my main setup (all plants on different shelves of one open rack) is the reason that critters are able to move so freely from one thing to another, so once spider mites appear anywhere, they’re nearly impossible to eliminate. I don’t think that high humidity alone deters spider mites, since I have observed them happily ravaging rooting cuttings inside of sealed bags and they laugh at being sprayed by water (no matter how much or how hard). Keeping them from reaching those plants in the first place is probably the main reason for your success.

I haven’t succeeded in pollinating ‘Ross Rambler’ (I assume the original) so far, or in getting decent pollen from it, but probably need to try harder or figure out if there is some trick to it. It does set hips on its own, and others have used it in breeding, so something must work–maybe it’s just picky about which pollen it will accept. I should probably just try sowing those seeds to see what comes up. If a more fertile/easier seedling ever appears that is otherwise equal (or close enough) to the parent, that would still be a pretty useful improvement from my perspective. Some R. laxa-derived hybrids have been very fertile and easy to work with compared to ‘Ross Rambler’, but I wonder if most of those were bred from tetraploid forms rather than diploids like RR. I’ve never seen R. beggeriana being traded in the U.S., unfortunately.

Hi Stefan,

l did have a sort of non-success with crossing RR#1 with Merveille as the seed parent back in 2022 … but doesn’t count for as Jeremy Clarkson calls his farm “diddley squat” … though one germination occurred, ended up as sort of a mini, never grew and didn’t last the summer.

Mind you that was only germination from a cross with a good to excellent seed parent, but as mentioned there was only one, from a half dozen hips pollinated and seeds stratified.

It definitely tells me that with even with both parents having a ploidy indicating good potential compatibility, a great seed parent germinator like Merveille, that using RR#1 as a pollen parent will be a challenging task. Never seen a hip on my bushes so used a pollen parent.

The beggeriana were particularly well received as only ones that germinated so far … on my 4th warm cycle and nada.

We are provided with the below photos of the bush and blooms taken July 19 2023 by Margit.

Over exposed was author noted, and as I note, because Alberta’s prairie summer sun can be very bright - as expected in Really Big Sky country - but long daylight hours absolutely fantastic for rose growth - not so much the winters.

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If my understanding is correct, RR #1 (aka Alberta Bouquet) is a hybrid offspring of ‘Ross Rambler’ with an uncertain pollen parent that produces few (if any) hips and probably has low overall fertility, not to mention having an uknown/undocumented chromosome number. ‘Ross Rambler’ itself is diploid, so RR #1 isn’t terribly likely to be a tetraploid like ‘Merveille’ probably is. That might help to explain your low yield of seeds and seedlings from that cross–but not necessarily the deleterious/lethal traits that you noticed in your seedling.

Do I remember correctly that you had gotten some other R. laxa plants now? With any luck, those will be tetraploid versions of that species, and in that case they might work better in such a cross. Normally in roses, using a higher ploidy parent seems to be more successful in terms of seed and healthy seedling numbers when it’s used as the pollen donor with a lower ploidy seed parent, although the chromosome imbalance could mean a greater number of triploid offspring that may or may not be fertile. Reversing the direction of the cross often yields drastically fewer seeds/seedlings, but seems to increase the percentage of seed production from unreduced pollen when it does happen–i.e., the offspring are more likely to be tetraploid. Of course, wide diploid-diploid crosses could be equally infertile compared with triploids, if not worse, a la ‘Polstjarnan’. A fertile triploid “bridge” rose could be very handy, if such a thing exists or if it could be created from species crosses in this Sect. Rosa/Cinnamomeae group.

I do love the silver-blue-gray foliage of R. beggeriana and R. laxa. The trait gets a bit diluted in their hybrids, but still lends some of them a hint of pewter that can be attractive and hints at the rose’s cold hardiness. I wonder, how high would R. beggeriana manage to climb there with support?

Hi Stefan,

l was mistaken, RR#1 not on my defined ploidy table.

I do know that not due to my thorough paper research, l fluked a few good crossing with Merveille, as tetra x tetra during the ~ 169 crossings 2022 garden reconn survey.

Merveille assigned tetra ploidy by my garden ownership royal prerogative through royal divine guidance … in other words not found but noticed species documented by the meticulous abbey monks as tetraploid :slight_smile:

You are correct finally scored a defined R laxa (Retz) from an Eastern friend that came from the Montreal botanical garden. Going to be a couple years before they bloom. Also scored a Retz from an Alberta botanical garden friend that bloomed in 2022. Except missed opportunity as didn’t notice the few blooms, but noticed terrific hips in fall. Didn’t see a bloom last year.

edit 1 info

Also note after chewing on it - as you mentioned, but not with my 100%+ cert. accreditation - that could have separate dip and tetraploid Alberta R laxa. examples - they were labelled as such when collected by me based on passed on info of work done by southern Phd researcher. Tetra is the one that bloomed first, still waiting on diploid.

Both ”loid” examples collected at same time. Tetra growing the best, but tenuous to conclude anything as it is in all day sun, while other in cold north garden.

end of edit 1

So the stock is there, and includes with R. lax (Retz) … and R beggeriana normalis, R. beggeriana nigrescens, and maybe potential Begg crosses from this years germinations … cinnemoa (sic) exists in garden. Also spino and hybrids stock, and odd agatha and gallica challenges waiting (have not succeed with latter).

Edit 2 April 5 2023

Should add birds in the climber bush, not in hand, to be added to genetic inventory, hopefully in the hand before May.

Have on order “Above and Beyond” rose samples to test in back cold Finn-like garden, but little snow, one for the coolish Bermuda-like front garden and one for the east side Kazakhstan-like (cold bone dry desert like - bakes - forget to water) climate garden.

Once patent, if any expires, and based on performance, another potential source of genetic “climber-hardy” material to test with yellow peach color. Based on northern Alberta recommendation to try. Hybridizer looks like they had good fortune with R laxa - Virginiana

End of Edit 2

The mentioned were pursued due solely and jointly, for zone and existing historical successes … only thing left … is the long, long wait for some to bloom … and selecting pollen / seed parents and a big whopping serving of hobbyist luck.