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Frost dates, chilling hours for Santa Clara County

Posted by riotbrrd z9 / Sunset z15 / No (My Page) on
Mon, Feb 16, 09 at 22:58

I attended a great class this weekend with Nancy Garrison, a local fruit expert with the Santa Clara County Master Gardeners program. Here's some info she gave us:

- Last frost date for Santa Clara/San Mateo counties is mid-March to very early April

- Average chill hours have decreased considerably in the last few decades. In the early '70's, we had about 1200 chill hours on average, but now it's down to 400. She mentioned this makes it very difficult to grow cherries except for one or two varieties (Lapins included).

BTW, the class was held at Common Ground garden supply & education center in Palo Alto, which is a great local resource.

Cheers,
Kim


Follow-Up Postings:

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RE: Frost dates, chilling hours for Santa Clara County

Nancy Garrison has been the UCCE Farm Adviser for Santa Clara county for many years. She volunteers to teach classes for qualifying new Master Gardeners as well as for the general public. I tend to believe her and am sad to hear how all that asphalt paving and thousands of new chimneys plus all the auto exhausts has affected the temperatures of what was once a prime fruit growing area of California. Al


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RE: Frost dates, chilling hours for Santa Clara County

Where can I find frost/chill info for Butte county?

It seems that our frosty nights have increased considerably over the past couple of years.


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RE: Frost dates, chilling hours for Santa Clara County

riotbrrd: I would have thought just the opposite . . . more frost/chill/cold in the past couple of years. I guess it's because I'm getting old and really feel it more. According to the local weather report, we're supposed to get another storm coming in Saturday and staying for a few days. I hope so, as it might keep us from water rationing later. I live near the Santa Cruz mountains, so we always get lots of rain. The one coming tomorrow is from the South, so it will be warm, and should be heavy rainfall. We used to call those tropical storms "The Pineapple Express", but I haven't heard that term in a long time? Probably because all of our storms have come down from the Gulf of Alaska in recent years.


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RE: Frost dates, chilling hours for Santa Clara County

wilbilt Butte county has such a variety of micro climates you will need to call your county UCCE extension office to get reliable local knowledge. Al


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RE: Frost dates, chilling hours for Santa Clara County

Actually, they are tracked by county, daily, on this website. If the spots in your county don't sound familiar, click on one, and keep clicking though the successive links, and you will eventually get to a map of where the tracking sites are. Also check your adjoining county--I actually discovered that where I am in Sacramento, my nearest site is in West Sacramento, which is in Yolo County, not Sacramento County. (Unfortunately, apparently the Santa Clara site has been down all year)

Carla in Sac

Here is a link that might be useful: Daily chill hours in CA


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RE: Frost dates, chilling hours for Santa Clara County

sautesmom, Thank you very much for that link.

Although the Butte County recording station is in Durham, which is quite a distance from where I am, the topology is similar (i.e., flat and open).

The history confirms my "seat of the pants" observations noting a colder trend, mostly from the middle of December onward.

The Yuba County site at Browns Valley is much closer, although more sheltered. That data is showing a similar trend as well. Cumulative hours below 45F are nearly double what they were in 02-03.


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RE: Frost dates, chilling hours for Santa Clara County

I live in Napa county, which lists two sites, both in the valley, one north and one south. I live 300 feet above the valley on the North slope of a mountain. My chilling hours will vary considerable from either measuring site. My local county farm adviser is aware of the topography of the county and the location of the "frost pockets". For this reason I value local input. Al


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