It is just a baseline to start. They welcome updates from people who grow a rose to let them know where it is hardy. The editors at HMF can't know where every rose is hardy, so they rely on outside contributors (us) to provide more information.

Do they take that information from members listing it in their gardens? Or do you have specifically email them?

For instance, I pulled up Salet, and it listed hardiness to 6b. It seems HPs are either 4b or 6b. :)

Eric

They go by the class unless they have clear information (which may not be any more reliable). Most of the hybrid teas seem to be rated 6b or 7b. You can probably grow these in Ohio 6a. Of course all HTs will need the graft buried and maybe some additional mulch. You don't expect any HT to be cane-hardy there, do you?

I see they have Garden Party as a 7 and Peace as a 5, but GP may be the hardier variety, so don't take these ratings too seriously. Some of the ones I checked that were rated z. 7 actually are on the tender side, for ex. Sweet Surrender and Valencia, but others, for ex. Savoy Hotel and Sunset Celebration, are relatively hardy for me.

In the middle zones, hardiness differences among HTs may come down to 6-inch stubs vs. no stubs, not exactly a deal-breaker.

Also, the main founder of HMF gardens in the northeast, where tender roses appear to be harder to grow than in the same zone in the midwest.

^ I forgot this was the ARF, sorry for the poorly chosen examples.

The main founder of HMF was just a little north of Philadelphia, not too far from where Flo-Zephy lives. She was in the colder half of 6b, and struggled mightily with HTs. So from her personal experience, HTs were not hardy in 6b, and most of them ended up in HMF as zone 7.

From years of listening to people here and on rgr, my best correlations are that you pick up about half a zone between here and Michigan/Wisconsin, and another half a zone between the midwest and places like Colorado. It's probably connected to moisture issues and summer heat. How that relates to a place like Cincinnati I really don't know. I will say that I first started with roses near Youngstown, OH. As a raw kid, I could grow better HTs there than any I've seen around here, and I've been to most of the serious exhibitor/CR gardens. It's the climate.

For roses set from a zone 6a to 6b you might just take chance or check out what grows well in your area. It is very dependant on local climate, snow cover in winter, how soon weather heats up on spring, cools summers, hot summers,... In my experience there are just a few hybrid teas and floribundas that really do well in a zone 5 or equivalent. The average minimum temperatures don't tell everything. I see that many of the hybrid perpetals are set to a zone 4 or 5. The hybrid tea Ophelia is set to a 4a while it's sport Mme Butterfly is set to 7b, that is a bit peculiar. In my garden the two are very much the same except for colour.

Not sure how we got on HTs :)I've only got a couple, and I've gotten away from them due to hardiness/form.

I've learned enough to know that all mosses, gallicas, albas, damasks, HPs, and portlands are okay here. I know teas are marginal at best. 95% of bourbons too (SdLM died) Where I'm less sure are some of the shrubs, noisettes, and polyanthas.

Tao, it's the inconsistencies you point out that I'm talking about. I think floribundas are hardier here. I grow Honey Perfume with almost zero dieback.

Eric

oops, meant to say 95% of bourbons are good

Sorry about the hybrid teas, I was just thinking out loud and they are sort of a well known territory to compare.

Here I have most cane damage on Souvenir de la Malmaison and Boule de Neige. Louise Odier, Great Western, Gruss an Teplizt not particularly much. Pertenianas can somtimes surprise with impressive winter hardiness.

It seems to me that zone 6b is some kind of default setting on HMF. Can you believe they rate the herbaceous peony "Sarah Berndardt" 6b to 9b??? Herbaceous peonies were custom made for cold zones. Sarah Bernhardt does fine for me in zone 4a and I'm sure it does fine in even colder zones that mine.

6 is a medium zone, which makes it good for a default setting, if that is how it is being used. I pay attention to zones only if they are at farther extremes. If it says zone 4 or zone 8, then I know there has been significant research or feedback. Zone 6 basically tells me "it depends."

Zones are about average minimum temperatures. That is all they signify. They do not speak about microclimates, mulching, soils, humidity, winds or latitude (sunlight), or temperature fluctuations. Lots of plants, including roses, can take a long cold winter, but what they can't take is a winter that warms up at the end of February and then gets blasted with late freezes in March or April.

Zones are a guide and should be used with at least a teaspoon of salt.

.....

Anyway, CCG, you ought to bring your questions about specific varieties here rather than shying away on the basis of HMF's zone settings.

One point to make-- polys, some hybrid musks, and other strong repeaters can be grown as dieback plants, just as HTs are in zones 5 and 6, wherever they are crown hardy but not cane hardy. They would just stay much smaller than in milder zones.

Thanks Michael. I'll always consider both HMF and GW valuable resources. I just try to do my research before I bother everybody here :)

Eric

I think this points out something very important about HMF: the members who use it are asked to submit information about the roses they grow and where they grow them. If you grow a specific variety of Hybrid Tea (or whatever) that shows significantly better Winter hardiness than most others, then by all means submit a Comment on the item's Comments tab to indicate that you have grown "Rose X" in zone 5 with no protection, etc etc. The Comment's tab is one of the most useful options on HMF as long as we the growers submit our personal experiences for others to learn from.

As for the default Zone listings for many roses on HMF: the information should be viewed in much the same way you look at the Manufacturer's Suggested List Price when buying a car or a Television.

Thanks Paul, good point. I've been documenting how much dieback I've gotten on my roses this year, and will add this info to HMF comments. A surprise for me, climbing Pompom de Paris (a climbing China) came through relatively unscathed. The lowest temp we had was -3, so the 6b is accurate on this one (at least in my experience).

Eric