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Fruiting Date Palms in Northern California zone 8-9?


kylemtncruzr
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Hello, my name is Kyle. My horticultural journey has lead me from bonsai, cacti, and now palms! But what I love more than looking at palms is eating their fruit! So my first major palm purchase will be a fruiting variety, Phoenix Dactylsomethin, but I am concerned about their fruiting ability in Northern CA.

Upon searching, I have read various times that you won't get fruit out of a palm in N CA. (Oh yeah? >:])

I'm hoping many of you will laugh at a Californian with his first world problem and tell me, of course it will fruit.

I'm in Auburn CA. Edge of zone 8-9. Closer to 8. 1700'.

I found a nice little gem of info Fao.org that seems like it's the date palm farmers mini almanac.

Fao.org-

"The above two criteria (flowering temperature and fruiting period) allow the calculation of the heat units, which correspond to the sum of the average daily temperatures from flowering time till fruit maturation, that are necessary for a given variety under a given environment. Different methods of calculating this heat unit value were used by the following authors:

- In 1879, Cosson estimated the sum of heat units necessary for Algerian date varieties as 6,000 °C. Similar results were obtained by Fisher (1883) while working with Egyptian varieties (6,136°C). Those authors' techniques were based on using the earliest date in each place when the temperature first reached 18°C in the year, and the last date of the year when the temperature dropped below that value.

- De Candolle (1883) considered 10°C as the growth's zero value. By subtracting it from the average daily temperature and then adding all the obtained values together, he found that 5100°C was the required heat units to ripen fruits of some date varieties completely.

- Swingle (1904) added the daily temperature maxima for a period of 184 days. The growth zero value used was 18°C (since the flowering process does not commence below 18°C) and consequently the value of heat units for several date plantations are shown in Table 24.

- Munier (1973) used the same technique as Swingle but differentiated between varieties such as Gharas, Degla Beida with 180 days and a heat unit value of 1,800°C, and Deglet Nour with 200 days and a heat unit value of 1,890°C. His results, presented below (Table 25), concluded that the value of 1,000 °C is the minimum limit for growing a productive date palm.

TABLE 24

Value of heat units at various date growing areas in Algeria and Iraq

Plantation/Country

Heat Units (°C)

Laghouat/Algeria

2,327

Biskra/Algeria

3,049

Ayata/Algeria

3,295

Touggourt/Algeria

3,666

El Golea/Algeria

3,990

Baghdad/Iraq

3,898

Source: Swingle, 1904.

TABLE 25

Heat units at various date growing countries

Plantations/Country

Heat Units (°C)

Elche/Spain

792

Laghouat/Algeria

990

El-Kantara/Algeria

1,170

Touggourt/Algeria

1,854

Bechar/Algeria

1,620

Atar/Mauritania

1,860

Kankossa/Mauritania

1,836

Nema/Mauritania

1,903

Basra/Iraq

1,872

Kidal/Mali

1,841

Kayes/Mali

1,980

Agadez/Niger

1,827

Bilma/Niger

1,860

Largeau/Chad

1,860

In conclusion, the value of the heat unit is of great importance for defining the suitability of a site in which to grow a productive date palm, to eliminate areas that cannot grow date palm, and also to help in variety selection. Furthermore, the temperatures shown in the above table can be regarded as optimum for date cultivation."

End

-Fao.org

My major concern was seeing that my heat units are greater than those of Iraq, Egypt etc. I don't think my math was off, but maybe the amount of fruiting days I chose (180) whereas Iraq and Egypt probably only need 2/3 of that time.

Auburn CA May-Oct

Hi 76 85 92 91 86 76

Lo 50 56 61 60 57 50

Av 63 70 76 75 71 63 Av = 69

69x180days = 12420'F = 6882'C

Indio CA May-Oct

Hi 93 102 107 105 101 92

Lo 64 71 77 76 70 59

Av 78 86 92 90 85 75 Av = 84

84x180days = 15120'F = 8382'C

I can mimic Indio heat with a greenhouse, but how to keep an arid greenhouse is not clear to me.

Or make a cold frame as high as the woody trunk to keep trunk mass and soil 100' and have the palm branches blowing in the wind?

Or just plant the dang things you silly Californian! HAHA! Part of me wonders how many palms are over peoples faces right now.

I just don't want to drive 1000 miles to drop $100's on some near mature date starts if they won't fruit.

Any help or hope here? I want some dates!

Thank you :)

-Kyle

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I see mature fruiting dates in landscape trees in Modesto.

Sadly, there in a shopping mall parking lot and they cutdown the dates before the ripen.

Auburn, being at 1300-1700ft elev. would have an average temp about 6-5 degrees lower than the valley overall .

One other thing to consider is your dewpoint is higher than maybe ideal... and lets not forget rain at fruiting time?

Do your research... you might find a fruiting variety for your area.

Jeff

Modesto, CA USDA 9b

July/August average 95f/63f

Dec/Jan average 55f/39f

Average lowest winter temp 27f

Record low temp 18f

Record high temp 113f

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If you have hot summer and relatively dry but prolonged warm fall you may be able to bring to decent fruition many date varieties. Maybe dates will not be of top quality, which is of course a significant factor for their commercial cultivation, but they will be anyway decent in shape and taste. Some varieties are used to be eaten not completely ripe, so this may be another factor for the choice of variety for your place. Also many people have different taste for dates. I, personally, do not like much the wrinkled, sugar-rich dates, I prefer instead the less sweet ones with a kind of apple flavor. Eitherway it is necessary that fruits are pollinated and pollination is not that easy if left entirely to nature. For better results you will have therefore to ciltivate a male specimen, gather the pollen and hand-polinate yourself female inflorescences.

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I think rainfall and humidity may be a challenge for you. Maybe there are some varieties that are more tolerant of both and or flower and fruit at a time less likely to encounter humidity and rainfall. I think Jelly palms or Butia may be another fruiting palm that you could grow.

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Your heat unit calculation is missing an important element: temperature curve during the day. Both the Mediterranean date growing regions and the Coachella Valley in southern California benefit from much higher night time temperatures. Average low in Indio is 80F, almost your average high.

If you found a calculation based on heat hours, you would find your dates would not ripen before the Fall rains arrive and make them rot off.

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Cool thanks everyone. I don't think I am worried about rainfall as the fruit would be covered, so that would buy some time.

I have also discovered Del Real Date farm in Salinas and they were the best dates I have ever had in my narrow date tasting history. Their website has pictures of their dates outdoors, but their googled address shows greenhouses. http://www.delrealmedjools.com/SearchResults.asp?Cat=1513

Maybe I will call and bug them with questions. Salinas stays pretty cool, at least Felton did where I grew up, never more than 85-90 a few weeks a year with the ocean breeze.

Solar dehumidifier and greenhouse sounds good to me, but expensive.

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Where in the world did you ever get the idea that Delreal dates are grown in Salinas? They grow lettuce in Salinas, not dates. The packing house and distribution center is in Salinas, but the dates are grown on a 40 acre palm plantation in Winterhaven in the Imperial Valley. See http://www.realtimefarms.com/source/6694022/del-real. These are dates with a decent carbon footprint, they're transported from Yuma all the way to Salinas and then packed and distributed from there.

You might want to reset your expectations in harvesting a date crop in Auburn, it's just not likely to happen. See this reference for more details: http://davesgarden.com/guides/articles/view/2762/#b

Though Phoenix dactylifera grow in a large variety of climates, including my backyard here in southern California, they generally do not make a good fruit crop except in arid, hot climates. One can see this species growing all over Hawaii, but rarely are there any edible dates on these palms. Some areas of Florida manage to produce a small crop of dates yearly, but nothing compared to the crops grown in the arid Middle East, North Africa or the California deserts.

I recommend you grow some date palms for ornamental reasons and if you want to make sure you might get fruit, then make sure you get a female as well as a male, and pick the variety with the lowest heat requirement. You'll have a 10-15% chance of harvesting dates. But if it fails, at least you will have two beautiful date palms.

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It was no idea, it is the only city printed on their package/website. Nowhere did I read where they are truly grown. It said somewhere some dude started it in 2000 as a hobby and it grew from there. Hobby to me sounds like growing against the grain in Salinas in a greenhouse :)

And what's with the quoted dude saying it won't happen but in an arid area, yet he says Florida can grow some? Since when is any part of Florida arid? I bet Auburn is more arid than anywhere in Florida.

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  • 4 weeks later...

Bump again, find a female date cultivar that it is known to flower early and use the pollen of Phoenix loureiroi (you have to plant several young plants of this last sp to make sure that at least one proves male, and according to loureiroi's provenance or even variety it may coincide in bloom with the dactylifera, in every case it is better that it blooms earlier than later to dacty, in first case you may have to wait about half a month that female flowers on dacty reach also maturity, in latter case however you'll have to wait for almost one year and then to use a very old pollen). Check this link http://ejfa.info/index.php/ejfa/article/viewFile/16660/8877 and read information esp on page 837 very carefully, it may help you considerably in your project.

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  • 3 weeks later...

Lots of dates fruited successfully in inland NorCal this past year because our winter was so warm and rainfall was so intermittent and paltry. Gary Gragg was harvesting dates from ornamental trees in Dixon and elsewhere in the Central Valley. But last winter was the warmest and one of the driest in California history. Auburn is moister and slightly cooler than the valley floor. Best bet north of the Coachella Valley for edible dates at least every few years is in Kern County and along the San Joaquin Valley especially on the drier west side, up to maybe Patterson (Modestoans, correct me here if I'm wrong).

Jason Dewees

Inner Sunset District

San Francisco, California

Sunset zone 17

USDA zone 10a

21 inches / 530mm annual rainfall, mostly October to April

Humidity averages 60 to 85 percent year-round.

Summer: 67F/55F | 19C/12C

Winter: 56F/44F | 13C/6C

40-year extremes: 96F/26F | 35.5C/-3.8C

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Lots of dates fruited successfully in inland NorCal this past year because our winter was so warm and rainfall was so intermittent and paltry. Gary Gragg was harvesting dates from ornamental trees in Dixon and elsewhere in the Central Valley. But last winter was the warmest and one of the driest in California history. Auburn is moister and slightly cooler than the valley floor. Best bet north of the Coachella Valley for edible dates at least every few years is in Kern County and along the San Joaquin Valley especially on the drier west side, up to maybe Patterson (Modestoans, correct me here if I'm wrong).

Jason you are on point, in my observations. In years past, T dactylifera does well here, and does fruit- I've observed trees just a couple miles from my house for many years. Problem has been: right at that critical time when they need more time to finish ripening- it cools off. And gets wet.

This past year was an anomaly- it was dry as a bone, warm during the day- and they ripened.

Although this one and W. filifera grow here, and germinate readily on the ground....the leaves just don't have that perfect glaucous look that is attained in the Coachella Valley.

Glenn

Modesto, California

 

Sunset Zone 14   USDA 9b

 

Low Temp. 19F/-7C 12-20-1990         

 

High Temp. 111F/43C 07-23-2006

 

Annual Average Precipitation 13.12 inches/yr.

 

             

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P. dact. "Medjool" is widely grown around here in N. Florida. ....they sometimes fruit to completion, but I have not sampled the fruit. Maybe this year I'll try it if I can find one that has recovered enough from the Polar Vortex to fruit.

David Simms zone 9a on Highway 30a

200 steps from the Gulf in NW Florida

30 ft. elevation and sandy soil

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  • 6 years later...

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