Moss Roses and Powdery Mildew

Hi, folks,

Has anyone noticed that moss roses are more susceptible to powdery mildew than other kinds? They seem to be in my garden, though I don’t think I have a large enough sample to say definitively. Some of my new moss roses are very susceptible the first year but clean afterward. Anyone else seen anything like this?

Moss roses, for me, are usually full of powdery mildew on the buds.

I belive it’s because the moss traps moister all around the bud, thus making it prone to mildew.

The leaves… well, it depends, really.

Some of them are disease free such as Scarlet Moss.

Others, like Goldmoss, tends to have mildew on the tip of leaves.

I had Single Moss (mislabeled Common Moss) for about 4 years and it didn’t have much problem with powdery mildew. If it got any, it was late in the season and not very much. I shovel pruned it last year because it had other health issues.

I planted Henri Martin this spring and the young leaves are covered in PM. I have it planted next to Metis, which is a PM magnet. Other plants near Metis do not have PM, so HM is definitely more susceptible than they are. I’m planning to move Metis this fall yet, so I hope HM will fare better next year.

For me the Mosses are on par with the Gallicas for PM susceptibility. I have Charles de Mils and it has PM as bad as Henri Martin. CdM gets PM every year, so I

Here in the San Francisco Bay Area, my Scarlet Moss even gets powdery mildew on the petals of the open bloom - something I rarely see on other roses!


Me too, Gail… in San Jose.

Scarlet Moss was pretty clean here, just north of Hartford CT. It had a bit of blackspot but nowhere near what my HTs had. No mildew at all.


The Mosses in general have a propensity to Mildew, yes. I think it has something to do with the excessively glandular nature of the buds in particular that attracts and fosters Mildew. Some, like Scarlet Moss fare better than others. Some of the OGR Mosses are very Mildew resistant once mature, as you’ve found. my Henri Martin, and Capitaine John Ingram, to name just two, are very clean now as 7 year old specimens, whereas they did Mildew quite a bit in late Summer when young.