My thought would be that being that close to the ocean near San Francisco your temperatures are probably cool enough for the gallicas. You have quite a prolonged period of low temperatures and, of course, in the shade it's going to be cooler than in the sun by a considerable number of degrees so it may be a combination of the two.

Ingrid

There's also the fog Ingrid, which chills the air even more. I certainly can't grow roses that like heat!

Diane

No.

Lack of summer heat is not the same as low temps. Consistently below 45 oF is what you need for winter chill. I've lived there. You get minimal winter chill. Fog and shade lower summer temps but are irrelevant to winter temps. You get more chill than SoCal does but that ain't saying much, is it. In your area, you have to pay careful attention to winter chill hour requirements when planting deciduous fruit trees like apples, but you can grow low-chill-requiring cultivars there. That's a good indication of minimal winter chill.

Your gallicas are doing well because, IMHO, their requirement for winter chill is way overstated. I suspect there are other environmental factors at play when people can't get gallicas to grow in warm winter areas - like humidity, summer high temps, soil type, water quality ... so many possible factors which could be acting in combination. They probably won't grow in tropical areas but California is not tropical.

My gallicas in Sunset 17 in Redwood City did pretty well too. No winter chill to speak of there. Now I live somewhere that really has winter chill. Even so with temps that can dip into the single digits, and not break out of the low 40s for weeks at a time, we're considered a mild winter area. Gallicas here bloom in June and July.

Wild Rosa gallica is native to southern Europe and Turkey. I don't think it gets all that cold there in winter either. That's the original Mediterranean climate, typified by mild winters and dry summers. They'll take truly frigid temps but that doesn't mean they need it that cold.

Thank you so much for that very clear explanation, reg_pnw7. Interesting to hear that Gallicas did well in Redwood City too. You've inspired me to do more research on the history of Gallicas.

Diane

I agree with what pnw7 wrote about the multiple environmental influences being at work as well as the overstatement of winter chill requirements (I think something similar happens with overstatement of alkalinity range requirements for particular classes of roses). Pnw7, I think that is good reasoning about considering the source of an ancestor species and what conditions were like there.

For me, I've grown the gallica Jenny Duval for around 20 years in the city of Claremont, CA. Fortunately when I bought it I had no clue of the need for winter chill. It hasn't seemed to retard the blooming of this rose because she is a mass of color every spring. My albas and damasks are just as reliable. They must have enough of what they need to make them happy.

Claremont is similar to neighboring Pomona in winter chill, and I have a link for winter chill records maintained by UC Davis for various cities throughout California including Pomona. I don't see San Francisco on the list of cities though Diane, but maybe something else close to you is?

Melissa

Here is a link that might be useful: Cumulative Chilling Hours Link at UC Davis

Thanks Melissa. I did a search for winter chill for Pacifica where I live and found out we have less than 400 hours of winter chill (below 45 degrees).

It certainly makes sense that if Gallicas originated in a mediterranean climate that they wouldn't need as much chill as everyone seems to think.

Diane

Here is a link that might be useful: winter chill for San Mateo county

It depends upon WHICH "Gallica" you are referring to. In Granada Hills (San Fernando Valley) Cardinal de Richelieu flowered with no problem. Charles de Mills almost never flowered. I could only get a few, begrudging blooms from him by literally packing him in ice several times over winter. Not worth it!

As the "Gallicas" were massaged closer to Hybrid Chinas, the total chill hours were reduced. It's like growing apples and selecting varieties which require 500 hours of chill versus those requiring 150 hours. Not all "Gallicas" are created equal. Kim

I can appreciate what you're saying Kim and I'm trying to determine which Gallicas will do best for me and as I'm no expert on a rose's family tree, am not sure how to approach this.

I do know that Gallica Officianalis performs beautifully for me every year but from what you seem to indicate, it shouldn't. Appreciate your thoughts.

Diane

Another thing to consider is micro climates in your yard or area. Cold air drains and usually follows water, so if you have a creek on your property, you might get a bit more cold air than others in your city.

It's a crap shoot, Diane. Even the accepted "pure Gallicas" can vary quite a bit. It all depends upon the genetics of the particular variety. Probably the best way to judge is going to be through others' experiences. Those whose winters are milder and report better bloom, should give you some decent indications of what to expect. It does appear to me, based upon how many roses have performed over the past nearly thirty years in areas around me, the greater the summer heat and the longer its duration, the greater the number of winter chill hours are going to be required. It seems as if high heat hours negate winter chill hours. Even though it gets significantly hotter (up to 50 degrees on the same day!) here than it does along the coast in SoCal, and the winters are noticeably colder, a number of the cold hardy, old European Garden Roses have been easier to get to flower (not really WELL, but some at all) along the coast than here inland. Very few have been really GOOD here, but it appears the cooler and more even the climate remains, the easier it is to get some to flower at all. Where these types grew in The Study Plot at The Huntington, many flowered better than in my Newhall garden. Newhall got much hotter and much colder than San Marino, yet the cold hardy, once flowering, European type OGRs gave a lot more color there than in Newhall. Most have done so poorly for me, I learned many years ago there were far too many other types which are MUCH happier to live with me. I'll take that.

Unfortunately, there isn't very much information about the origins of most of the roses in question. They originated long before actual "breeding" began. For too many, the only information there is concerns who either discovered them or raised the seed. Kim

Thanks Kim. Perhaps it's because I am on the coast that is helping to do the trick.

Tomorrow I'll put up a post asking who's growing Gallicas in mild winter areas and what their successes have been.

Kippy, no creek in my garden. Sure would be nice if there was.

Diane

Hi Diane, you're welcome! Kippy's right about how a change in elevation, even just a few feet, can make a world of difference. Particularly if the cold air which pools there, is trapped by structures or plantings and can't quickly flow out of the area. In the Newhall garden, there was quite a change in elevation. It was sufficient enough for me to get some of the Gallica seedlings to flower at the bottom, where they wouldn't at the top, and I could grow cold tender bulbs at the top where they would freeze at the bottom. And, in that location, the cold didn't get trapped, but flowed right out across the golf course and into the community.

I think you're right about your coastal location enabling you to get some of these to flower. Good luck on collecting your data! I hope it helps point you to more which will perform for you. Kim

I thought I would add, that I am not sure how accurate some of those "chill hours" readings are.

Jeri, in Camarillo is listed at the upper 700's and Moms place is listed as upper 300's.

If our reading is from the airport, it is so close to the ocean the readings will be more even. If it is from the County Fire HQ, it will be fairly accurate for moms place. I have tried finding the stations with out a lot of luck and since the number range so much it did not seem all that important.

I put an avocado in a location I am hoping it gets extra water from the neighbors but am praying it is out of the cold draft. The cold draft area is where I want to put a cherry tree. I put 2 out of zone plants in a different cold zone, so far they look okay but have only grown so much (red currant and gooseberry-SoCal people know just what a zone bend that is!) I only have so-so hopes for those two plants because as cold as that area is, it is probably not the coldest spot on the lot. That area would probably also be the hottest in the summer, so I skipped it.

Just so any of you that have never been to San Francisco in the summer, it can be COLD. That is coastal fog, it comes in off the ocean at close to 100% humidity and not too much more than the ocean temps (if you are close to the water)

I think there is a song/poem about the coldest winter they ever had was a summer in San Francisco.

Cardinal de Richelieu Tampa Bay every year. Kim

If i only used water wise containers ....laughs. I'll take my reclaimed water from the city of st pete.

I am still very skeptical of this winter chill theory being necessary for old garden roses to bloom. Too many came from mediterranean type climates and flowered quite happily there. However, it does give people who've had trouble with growing them an answer. Not necessarily the right one, but an answer just the same. It really has made no difference here whether the year has been especially cold or hot, my old garden roses flower regardless year after year. No, I think it is more along the lines of what Pnw7 suggested, a combination of many environmental variables together that makes a difference. Not particularly winter chill. I don't think china genes matter one way or the other in this case. But now there is the suggestion we don't know much about the origin of these old roses except that we need to assume they have china genes if they bloom at all in mild winter areas? Not very logical.

I just added another gallica this year from Pickering, Aimable Rouge, and it is a lovely thing. Hasn't flowered yet, and I wouldn't expect it to on new wood. The growth is quite attractive with very nice leaves. Its next door neighbor is another newbie, the damask Duc de Cambridge which is VERY vigorous. I have coming next week another gallica, this time a recent Eurodesert import, Kraskoje Kawaskole. Not much is known about it in the US but the name suggests a link to red color (Jedmar on HMF may be on the right track there as the first word is very similar to the word for red in Russian) and possibly the Caucasus mountains. I've been before and there were certainly roses growing in the area I visited. The odd spelling of the name may indicate transliteration difficulties from cyrillic which isn't all that uncommon.

Pickering should have ordering open soon and they have a very tempting selection of gallicas (and albas!).

Melissa

Thanks Andrew. Richelieu is one of the dependable ones. Kim

Tessie, if chill hours weren't the more probable answer, what else would explain roses such as Tuscany Superb, Belle Isis, and other European once flowering OGRs flowering quite well as freshly planted, new bare roots after having been held in cold storage. The same plants not flowering in successive years in the same garden in which they flowered well as fresh plantings? The bud wood used to create them had been held in cold storage until budding. The bare roots had been held in cold storage until they were shipped. The existing canes produced quite good 'crops' of flowers, yet they never flowered again. I particularly wanted Belle Isis as it supposedly helped produce Constance Spry, a favorite of mine. I intended to use it with other modern floribundas to see what could result. I couldn't as it never flowered in Newhall after that. And, I got good, long chill hours, but also much more high heat.

I was only able to use Tuscany Superb pollen once, from that initial flowering of the new bare root. I produced two seedlings from its pollen on Sequoia Ruby. Neither flowered regularly. The more double one (linked below) was more reliable flowering than the nearly single, deeper colored seedling, but I couldn't count on it flowering each year. I eventually discarded the nearly single one and sent the original seedling of the more double one to Paul Barden where his greatly increased chill hour total and significantly less heat hours allowed it to flower.

I could count on MORqueencrest, Ralph Moore's Queen Elizabeth X Crested Moss hybrid to flower in Newhall. It flowered in Visalia. It flowers for Paul. It will NOT flower in Encino. Similarly, the everbearing, evergreen, thornless blackberry fruits all summer in Newhall, and has for the past fifteen years. It will not flower nor fruit in Encino. It is less hot and less cold here than in Newhall. To what would you attribute it? Kim

Here is a link that might be useful: Sequoia Ruby X Tuscany Superb

I cannot really add much to this debate apart from mentioning the requirements for winter chiliing are making it harder and harder to grow birches (betula pendula) in the southerly parts of the UK. Also, it does not happen overnight - the plants will gallantly struggle on for as much as a decade....but they will be growing backwards. These requirements are in the plants DNA - there is no fighting or 'amending' this (although I have heard of very dedicated (crazy) people using bags of ice!

This is an extremely interesting discussion, which I came upon after reading California Melissa's comments about Hybrid Perpetuals in a thread I started and got started thinking about this topic. I want to add my comments about Mediterranean climate as I know it.
Our garden is in the northern foothills of the Apennines in northern Italy. Our climate is probably pretty typical of that of a good deal of the country, a little warmer and dryer than in the Po Plain below us, chillier than on the coast. We grow temperate climate fruits, bulbs, and roses without difficulty; but Italian cypresses and pines, for example, thrive here, and olives do well in warmer areas once established. The Mediterranean climate as I know it, without achieving what most Americans would consider serious cold, offers chill hours in abundance. Most years in January and February we have week after week of temperatures in the thirties and low forties, with cold periods in the upper twenties. There have been warm winters in the twelve years I've lived in Italy, when it was possibly to go out in the garden and work comfortably for most of the winter, but I've never known the tulips to fail to bloom, or the plums, pears, and cherries to flower and fruit.
A fact I like to quote to U.S. friends is that we live just south of the 45th Parallel, about the same latitude as Bangor, Maine. Many Americans don't realize how far north Europe is, including much of Italy. The climate is different here. We have a hot dry summer, but we also have a long winter and a pronounced spring and autumn, and although temperatures rarely fall much below 20F, winter is plenty chilly, in part because the days are so short and it's humid a good deal of that time.
I agree with comments in this thread that the flowering of the once-blooming roses of European probably depends on a complex group of factors, and varies from variety to variety. But I do want to explain what cold is where I live, in an Italian environment of a common type.
Melissa

I would like to thank everyone for all their interesting and enlightening views on winter chill. You've given me a lot of food for thought.

Melissa in Italy, that was an eye opener about being in the same latitude as Bangor, Maine.

I'm going to post another thread to see what Gallica/Alba successes people have had in "mild" winter climates.

I'm kind of a late arrival to this thread, but I think that a couple more considerations might help. First, newer chill models show accumulations at temperatures up to 55 degrees which in San Francisco means two full months where almost every hour contributes to the chill requirement to one degree or another. Second, the chill hour models we use were developed for stone fruit and may simply not be adequate in dealing with other genera and finally, I question throwing out the original poster's hypothesis regarding the effect of shade. As a practical matter, we are all well aware of the tremendous temperature difference there is between shady and sunny locations, why wouldn't that play more of a role than the official temperature recorded under an instrument shelter which is itself located in full sun? (Instrument shelters have thin walls and lids that are located only inches away from the thermometer and so radiate a great deal more heat than a tree, hedge or building located several feet or yards away)

Ryan

Hi Ryan,

Thanks for your response. I know that my garden is cooler in temperature than neighbors across the street because I'm on the shady side which is more pronounced in winter due to the low angle of the sun. We get a lot of sunny balmy days in the winter (but not today, brrr) but because of shade on my side most of the day it's much cooler.

Diane

I tried the ice as well. I had a friend who liked to ski locally. He used to bring back a truck bed of snow for me at 10:30 at night a few times for me to dump on my lilacs and other experiments. I got some flowers but it really wasn't worth it and so I gave my lilacs away to a man who was moving up to the Idylwild area. I still wonder about using snow on lily of the valley in a shady area and putting some sort of styrofoam insulation over it to make it last. Digging up the roots and putting them in the refrigerator does not work. I want a new truck anyway and if the snow idea would work for lily of the valley I'd probably go for it.