I’ve caught a few comments here regarding this rose and it’s lack of fertility. I’ve not yet attempted any breeding with the rose and nor have I ever seen a hip set upon it. Any slight hope of it being the least bit fertile? With it’s extreme hardiness it sure would be great to take advantage of it’s genes! Thanks!
Terry
Looking on ‘HelpMeFindRoses’ it doesn’t appear that Polstjarnan has any descendants. That doesn’t mean it isn’t fertile. It could mean that nobody has tried breeding with it, or that nobody produced any hybrids worth introducing. You may have to go back to it’s parent, Rosa beggeriana. It has produced fertile offspring such as ‘schneezwerg’, which has led to so many hardy shrubs.
Mark Disero, Brantford Ontario, Canada
I will be certainly trying with it this summer, assuming my smallish plant blooms.
I remember Paul Olsen was speculating that the pollen might be viable and considered it a worth while path to persue.
In 2003 I pollinated ‘Polstjarnen’ with Rosa acicualris ‘Kinistino’ and obtained hips. But somehow I lost the seed. In 2004 I pollinated this cultivar again with several hardy cultivars but not one hip set. I guess it’s back to ‘Kinistino’ this year! There is no question that if fertile breeding lines can be developed from ‘Polstjarnen’, they could be valuable for developing hardy (Zone 3) Climbers.
Paul, thanks for your comments. I guess I shall go ahead and attempt some crosses and HOPE for the best! Indeed this is a valueable rose with genes we surely could make good use of! Thanks!
TerryR
I have only a small plant of 'Polstjarnen and just a few flowers bloomed this year. Swiped a couple of them with ‘John Cabot’ pollen just for fun and they set hips. This success has rekindled my interest in this rose to develop cold hardy (Zone 3) Climbers. It’s main value I think is the potential to develop Climbers having yellow flowers. I’ll puruse this next year.
I had a very hard time obtaining much in the way of pollen from Polstjarnan. I didnt have a huge amount of bloom. I tried collecting from about 10 flowers and came up with almost nothing. My plant started small this spring.
As far as vigor, it definetly has that. It went from a small plant in a 1 gallon pot to a near monster in 1 summer. Right now it has produced numerous 6 ft + canes and is doing a great job filling my species garden. I need to make some structure to attach it too to help keep in in order. I fully expect a large number of flower next spring.
Paul or anyone, I wonder if you could compare Polstjarnen with Ross Rambler. Is Ross Rambler as hardy as Polstjarnen? Obviously they have different flower (I greatly favor Polstjarnens flower over that of R.R.) but from a distance, they look fairly similar in my garden. I have them planted side by side and both are becoming monsterous. RR(at least the one I have) has been labeled as a diploid. I think Polstjarnen is a diploid as well?
What kind of advantages would you say (beyond flower) does Polstjarnan has over RR?
My plant of RR has set numerous fast ripening hips. It has also bloomed on and off during the summer. Mostly on new growth. New canes are almost always topped with a cluster of flower.
I will try some assorted pollen from my triploids on Polstjarnen next spring and see what happens. Actually, I will probably put any left over pollen from other crosses on it as well. Same with RR.
-Steve
Where does one obtain Ross Rambler from? Thanks.
Rob
I think Ashdown Roses was planning to offer it but dont quote me on that.
If Ashdowns doesnt end up offering it, I bet I could get a sucker of the plant I have to you.
SteveJ,
Ashdown Roses isn’t offering Ross Rambler at this time. If you have a sucker available to send to me that would be great. I’ll wait to hear from you on that. Thank you.
Rob
I just got a Ross Rambler last year. It is just establishing so I don’t have a lot of experience with it yet. I do have a couple seedlings from it that germinated recently. Last winter I took a couple cuttings before winter and the cuttings bloomed in the house and I pollinated them and got 4 seeds and am excited 2 germinated. I LOVE Polstjarnan. It is huge and spectacular in the garden. I had a very very hard time getting enough pollen from it to even measure 30 pollen grains for size for a study. I got one hip on it in the past and the one seed didn’t germinate. I am very excited for you Paul and the seed set you got. I counted the chromosomes of Polstjarnan and it is diploid as is the Ross Rambler plant I received. I suspect I’ll probably make a lot more progress with Ross Rambler in the future here than Polstjarnan because of the fertility. I am thankful to have them both though.
Sincerely,
David
Rob,
I did some digging yesterday but cant find much in the way of suckers. That surprises me considering how much growth it has put on, all of the new growth was on existing canes. I have a couple thin branches that were partially burried that may have rooted. I still need to clean up around the plant some. Perhaps I will try propagating from cuttings like David did.
Sorry I dont have better news. I have a couple of plants that I want to get suckers from and send out to people. I will keep you updated.
David, Its good to hear that other people like Polstjarnan as much as I do. I am looking forward to its bloom next spring.
On a totally unrelated side note, I have been growing pumpkins in part of my garden and had an attack of squash bugs that killed off a majority of the vines. The only pumpkin vines that were free of bugs and survived without problem were the ones that grew across and into my rose garden. The first rose they grew through was r. eglanteria. Wonder if squash bugs dislike apple scented foliage. As a consequence, I have a rose garden full of large ripening pumpkins.
SteveJ,
Thanks for the update. I appreciate you checking on a sucker for me. If something shows up in the future please let me know. Thanks again.
Rob
Steve,
Rosa laxa is cold hardier than ‘Polstjarnan’. In a Zone 3 climate, ‘Polstjarnan’ will often winter kill to some extent. But if the parentage is correct (a Polyantha cultivar being one of the parents), that should be expected.
It seems to me one of the main advantages ‘Polstjarnan’ would have over Rosa laxa in a breeding program, is the potential for a wider range of flower forms and colours in the progeny. Secondly, the canes of this cultivar are more pliable than Rosa laxa and can be trained as a Rambler. So perhaps some of its progeny would also have this characteristic. In contrast, the progeny of Rosa laxa is more upright in growth habit.
For anyone interested in knowing, ‘Polstjarnan’ propagates easily from softwood cuttings.
Paul, please keep us updated as to your results of ‘Polstjarnan’ x ‘John Cabot’. I hope the seeds are viable and good things come forth!
Terry
Rob,
I’m sending David some rose material this fall. It includes Rosa acicularis ‘Kinistino’ that I want to get into the States. I could include a ‘Polstjarnan’ plant, which he would likely be happy to pass on to you.
Paul,
Thank you for the offer of Polstjaran. That would be greatly appreciated. I’ll wait to hear from you or David this fall. Thank you again. 
Rob