Here you go

Dan

That link directs one to daves garden, I don't like daves garden. I don't use daves garden at all. I spend time upload my photos to help them with a data base, and then they were so rude to me and they refused to allow me to delete the photos when I quit.

I am really annoyed, and I wish I could delete your post. This is the Garden Web, the bigger and better site, and Daves Garden is the wanta be site, that mostly cators to gardener from the southern states.

I would not believe any thing I from daves garden that was supposted to pertain to San Francisco. I am going to email the moderators about having your post deleted.

Dave's is only providing a service with a reference to a government site, as Dan was in posting the link. Do you find the information inaccurate? In my case we have no government recording equipment here and so they gave the data from the three closest sites. San Francisco being a larger town will have a local site for climate information. Al

That link is actually to 'Let Me Google That for You', then I merely chose a service. Since we don't know where you are in that particular set of microclimates and you do, I merely gave you a pointer on how to get that information, rather than us guessing. And we have no way of knowing which facts you prefer, so the pointers were appropriate so you can choose preferred facts.

HTH.

Dan

The inquiry set up sends one to google, I looked at the URL and you typed "daves garden" in there. I did not look at the date, because I refuse to go back to daves garden for any reason. This is some kind of desperate set up to bring traffic to daves garden. I was hoping for personal experience from a real gardener in bay area instead of a government chart. I could have use the farmers almanac. I have already reported your spam postings. The reason people have a social site is they want to talk about things.

Please do not go to daves garden. I have found March 20 to Nov. 20, thanks for ruining my posting, dan.

Here is a link that might be useful: I found a useful chart on this page

tropical thought CHILL OUT

I typed in what is the last frost for San Francisco in to "let me google that for you" and the first result was the farmers almanac. Since the white dome hydrangea is only mail order, I can't find one locally, and it will only be a small size. I would rather find a larger one, but I called several nurseries last year, and they were all very negative on the phone. I went down that big nursery in palo alto last year and they had tons of blushing brides but nothing more interesting then that. Little hydrangeas are very hard to keep alive I have been trying to get one called Berlin from half moon bay nursery to grow for years. It has the nicest flowers I have even seen. I am actually putting in a drip system this year, it may help.

Here is a link that might be useful: Farmers Almanc

I have ordered several Hydrangea from Joy Creek Nursery to be delivered this month. I lived in San Francisco for the first few years of my marriage and can not believe Hydrangea would not be hardy there, as they are here. I am growing at least 30 hydrangea some for over 40 years. Al

There is in fact no part of San Francisco which gets enough cold to kill a Hydrangea in a frost. The nursery at the San Francisco Botanic Garden is probably the coldest spot in all of San Francisco, and only got down to about 26F in the December 1989 freeze. What you may have had in 2007 wasn't nearly cold enough to be a problem for any species of Hydrangea, except for some of the tropical climbing Hydrangea species from Central America.

I also got a chuckle about a "last cold date for San Francisco", because in my opinion, in your part of San Francisco, it never really stops being cold except when the whole Bay Area is getting a heat wave. The problem can be that it never gets warm enough for many heat loving plants, even in summer, and that is a huge reason why things like tomatoes and Meyer lemons need all the help they can get, such as planting out of the wind and against a south or west facing masonry wall to accumulate more heat and counteract the predominant chill of all that fog and wind.

If I recall, you live out in the Avenues, the Sunset? Frost is negligible in that area, although it can get cold enough to get frost on the roof and grass, it isn't typically cold enough to kill most plants, except the most tender annuals such as Impatiens and Coleus.

I've found that some of the deciduous Hydrangeas in fact need more winter chilling than we get to do well, and some such as H. aspera cultivars failed to thrive for me here in Berkeley because our winters are too mild! Losing a Hydrangea in San Francisco is much more likely to be due to underwatering them when planted in soil that is old dune sand, and has very little organic or clay content to help hold moisture.

Here's a link to a comprehensive frost/freeze data for many cities in California. I like this table because it provides probabilities in your area for any potential freezes or frosts. If you look at my area in general (N. San Diego County, about 6 miles from the ocean), I'm not supposed to have any freezes, either. But that's not true. We can have nights that reach freezing, and plenty of frosty nights. And, even if the temps don't drop to 32 degrees, getting in the high 30's for some plants that are not well established, or sitting in a cold spot in your yard can get nipped, or even killed. (Although I also agree that this was not likely the cause for the demise of your previous hydrangea, as they thrive in zones where there are prolonged winters below 32 degrees - I had them in Indiana and they loved it there.) I have a cardboard fern for example, what was frozen on the east side of my house, were I have a pronounced cold spot, yet 4 of them just around the corner on the south side of my house, same distance from the house were just fine. Helpful to have this data, even if you're in an area that supposedly doesn't have any freezes :-)

Patty S.

Here is a link that might be useful: NOAA NNDC Freeze Frost Occurence Data for California with Probabilities

Thats a loaded question-winters day could be warmer than a June day..but,thats not what you meant. San Francisco has a 365 day growing season. Tomatoes die of winters cool,not frosts or freeze. I'm not sure if SF has had a true 32f since 1990.