Winterizing advice needed

Some of my roses are new to me this year and I would appreciate the advice of anyone experienced on what to do with them over the winter. These are the minis Joycie, Golden Gardens and Scarlet Moss, and the hulthemias Persian Flame, Autumn, Sunset, Peach and Roses are Red.

I am in the Connecticut River valley, USDA Zone 6a where we occasionally see an overnight low of -10

I can’t help you with cold tolerance though I do know the non-Hulthemia Moore roses were bred from fairly cold tolerant stock.

I would be interested to learn anything you can share about the disease susceptibility of those listed.

If the plants are still small, or are still in pots, then burial is probably the easiest and safest way to handle them. Because of the East Coast fluctuating winter temperatures, you may want to wait as long as possible before doing this, maybe well into November or even December, depending on what kind of season you end up having. They’ll easily handle nighttime temperatures down into the low 20s and mid-teens, but you probably won’t want to risk them freezing solid in pots above ground.

If the plants are growing in the ground, then you may want to explore mulching (as in, a mound of mulch over much of the plant) as an option - although it is slightly riskier due to eastern temperature fluctuations and winter moisture. Again, you’d want to wait as long as possible before starting, and something to prevent rain and snow from soaking down through the mulch would be advisable. The risk is turning the rose canes to compost by spring, which you can help to avoid by keeping things fairly dry. You may also want to mound a few inches of soil over the base of the plant first, as soil seems not to promote decay quite like mulch can (probably because it is already well-decomposed, and possibly because of the established microflora).

I wouldn’t personally consider most of Moore’s roses to be particularly hardy in the north, although there may be a few rare exceptions. Rosa persica by itself is probably hardier than many modern roses, especially in a reasonably dry climate, but I doubt any cold tolerance it possesses influenced the subsequent generations much; there is no way they would have been selected for this trait in California, even if it was passed on to some degree. Perhaps there is a surprisingly hardy member or two of the hybrids even still, which would be great to learn in time. 0 degrees would be one thing, and losses would be minimal to none, but -15 is another story altogether. There are generally striking breaking points in the hardiness of roses.

Robert,

I would be interested to learn anything you can share about the disease susceptibility of those listed.

They all blackspotted badly enough to defoliate but it was a bad year here for blackspot. Actually, they didn’t do any worse than most of my other roses in this respect but then I have a lot of older Weeks and J&P HT’s which are BS magnets. The only thing that didn’t blackspot was my little R. glutinosa.

Once I started spraying with Bayer they took off and I haven’t seen a spot on them. I should get some pictures before they lose their leaves. They are nice plants, actually.

Stefan,

Thanks for the advice. All my roses are in pots although the pots are buried to thier lips. For the HT’s I was planning to lower them more and mound dirt over the crowns, moisture isn’t a problem because the soil has virtually no organics and it drains well.

I have a bunch of grafts in band size pots that need to be overwintered too. Mike Lowe advised me to dig a hole, line the sides with plywood and cover it with styrofoam. I was thinking I might put the minis in there too, but the hulthemias are a bit too big for that.