German Rose Trials

I posted a reply to Paul’s “Going Native” about the German Rose Trials. There were two replies mentioning those trials, before I put in my reply about my translated article, so I thought why not start a NEW Post ! Will repeat my reply below.


“Going Native”

  • Posted by Paul G. Olsen on Mon, Sep 10, 2007

56 replies. Last reply posted on Sat, Sep 15, 2007


Just for the information of many of you :

“The German Rose Trials” are never sprayed in the first or in the second year.

I have translated an article from the German RS Annual into English for a local RS.

“GERMAN ROSE TRIALS’ talks about the rigorous testing that new German roses must undergo”

You will find it on my Articles page.

George Mander

Ps. I would also like to add that in some cities in Germany, mainly those near a river, you are not allowed to spray your roses at all. I have just called a hybridizer friend in Germany to confirm this. Relatives in Germany told me about it a couple of years ago.



You say in your article that 9 test gardens throughout Germany have been chosen for the soil and climatic conditions in which roses are commonly grown, and that roses grown there are given absolutely no protection from disease during test periods.


What kind of soil are these test sites comprised of?

Is the soil cultivated or turned intermittently?

What are the climactic and environmental conditions of these test sites, and are they comparable to North America?

It’s one thing to disclose that test sites are not given protection from disease, but what about rose pests?? Are there no pests in these areas?? Are their roses not given protection from harmful pests?

I don’t know Germany, but very interested to know if the area Kordes is conducting these rose trials have little or no issues with pests. There are places on earth where roses can grow happily without the threat of pests. Are these 9 official test sites one of them?

These are questions I would have liked to pose to Mr. Kordes if he had been able to attend the CRS meeting back in spring. Perhaps you can help me there.

Actually, there are 11 test sites. These sites are located in different areas in Germany (see ADR website). Climate differences within Germany range from zone 5 to zone 7, temperate near the coast and more continental in the south.

The roses are not sprayed, so no fungicides or insecticides (as far as I understand from the website). There are, of course, insects in Germany that plague roses, like aphids, thrips, stem borers, sawfly larvae, caterpillars etc. However, they are not that bad as midge or Japanese beetles, who do not occur in Europe.

On the website, you can also find the form by which judges judge a rose. As you can see most points go to the foliage (especially disease resistance). So only disease resistant roses will pass the ADR trial, but between those that are resistant the most floriferous and beautiful are selected.



Hello Dee. S & Rob,

I have beeen living in Canada for over 50 years and I have never been to one of those testgardens on a few visits over the years. On my next visit I will make sure to go to a garden or two and I will also visit the Kordes Rose Firm again.

So I can not answer any of Dee’s questions. I only translated what it said at that time. It was 1993 when I translated the article so things have changed a lot since then.

Thank you Rob for your information & pointing out the ADR website which I will visit whenever I get some time, of which I have very little as I am the only caregiver for my very ill wife.

I haven’t even much time for hybridizing these days as I can barely look after my own roses. Got rid of 100 roses in pots which were not my own.


Lest we thing that the Germans are giving up totally on -cides, some neighbors of mine were describing the German-made spray contraption that they bought for spraying their vineyard (on a steep hill).

Visualize an inverted “U” that goes over the vines and has sprays that cover the grapes completely AND has a basin that catches any drips/loose mist/other -cide carrying liquid that might enter the ground water. The caught liquid is recirculated and resprayed. (And the wheels adjust to keep the U’s sides vertical on different slopes.

They bought their unit from a German company in Canada.

I have GOT to see this thing in operation next season.

wow, brilliant. It’ll be interesting to see how America progresses with this tho since “organic” is becoming mainstream. but organic is costly even if mass produced…

I, for one, will not touch anything remotely carcinogenic tho.

Thanks for This George.

Sorry to hear about your Wife’s illness. Best wishes to you both for her speediest recovery.


Thank you Robert for your “Best wishes”.


I’m very sorry to hear about your wife, George; she must be a very special lady for you to take care of her. You dedicated a rose in her name, which to me is a declaration of love & devotion. I wish you the best in that respect, and that she may recover quickly.

And thank you Rob for the link and information.

George, I send you my best. I know about caring for a loved one. It takes the strength of a titan.

I salute the ADR program. I do believe it offers assurance only that its graduates will be resistant in Germany, not in the USA. Georgraphy tells that story. Germany is slightly smaller than Montana. Picture Montana placed vertically on the Canadian border where BC is, and you have the latitude.

The lesson of species disease resistance was brought home to me during a recent visit to the Arnold Arboretum in Jamaica Plain. Species that I’ve seen completely disease-free in Europe and elsewhere in the USA were coated with anthracnose in the Arnold Arboretum. I don’t know if it is a virulent strain, high disease pressure, or perhaps another lookalike disorder. I can say that it was impossible to ignore the black shotholes puncturing the leaves and coating the hips. Like every botanical collection, there may be some labeling problems, but whatever those species were (the collection is enumerated on HMF), many were far from perfect.

About the shiny leaf issue. I’ve been studying species in botanical gardens for a couple of years, and I see little correlation between leaf surface and blackspot. I hasten to add I haven’t studied species in the mid-Atlantic states where the pressure is the highest. I have seen large species collections in France, the Netherlands, California and Massachusetts. Leaf surface does not seem to relate to disease resistance. At the Arnold Arboretum, many of the shiny-surfaced California species suffered from a variety of fungal diseases, while in their native habitat, most are quite happy. I did see some evidence of earlier defoliation (bare lower canes on some species) but very little actual blackspot.

I’m slowly uploading shots to HMF, trying to confirm identities with botanical descriptions as I go. It’s a slow process.

George, I also send you my best wishes. And thank you for pointing out the ADR trials.

Cass, I also believe that being awarded with an ADR certificate doesn’t mean the rose will be resistant in the US automatically too. However, since I am located in The Netherlands I’m very happy to use those ADR roses. Many are doing very well in my garden, though not all are as bullet proof as I would like them to be. And they should be tried out in the US and Canada. Maybe some of them also do well there. I already read quite some favourable reports on GardenWeb about the new Kordes roses.


Hello Rob,

Thank you for your best wishes.

Since you are in the Netherlands, there is a nursery in Holland which is carrying a number of my roses since 2005/6.

The man to contact is Hans van Hage. Link below

and here the name and address of them :

Rozenkwekerij de Bierkreek

Zevenhofstedenstraat 9

4515 RK IJzendijke

You can also go to my listing at HMF and click on : “Buy from” to see which of my varieties they carry.

Link to HMF is on my Gallery page.




Arboretum or Botanical Gardens rose species (and some other plants as well) problem is that in the wild most grow apart with other plants mixed in between in a climate they had millenaries to adjust to.

Not growing close together with other species some being out of place. With a bad environment or neighbourhood the best at resistance will be desease ridden.

Even in the original nature environment there are exceptional occasions that go past plant adaptations.

Plant domestication first step is selecting for resistance to monoculture induced deseases. Something that was not done for our roses. On the contrary being grown by rich people there was an exciting challenge at growing exotic beauties with still more investments: greenhouses, understocks and still more chemicals.

A tendency that is broken… as Germany attitude spreads over all Europe as well as in your country as shown by Flower Carpet and Knock Out sales.

Pierre, I agree with you. A species that looks poor in the monoculture of a botanical garden is worth noting, just as a species that looks outstanding is worth noting. The Arnold Arboretum is not a small city garden. It is a large park of 265 acres (107 hectares). Species roses are isolated in a large park of Rosaceaces, so the monoculture is not only Genus specific but Family specific. The space is large enough to allow suckering roses to create and maintain thickets. The effect is impressive and informative. It is the best such collections can offer, apart from integrating Rosa everywhere.

I visit a smaller specialized botanical garden where the roses are integrated within the larger collection. That 61 acre/25 hectares garden is on a hillside. As expected, the health of the species roses is generally excellent - - except for disease-prone species in that environment. The difficulty with the integrated approach is that study is an athletic event. Four hours at the integrated botanic garden allows me to study and photograph about 25 roses on a good day. I was able to view and photograph 100 roses in an afternoon at the Arnold. If I had to find roses in a treasure hunt of 265 acres, I would still be there, searching.