What is your soil temperature?

[bubba 2,397]

I found a University of Florida Agricultural site that gives Air Temperature at 2 meters and then soil temperature at 10 centimeters.The closest I could find to me was at Ft.Lauderdale,which reported air temperature at 80 F.and soil temperature(10 cm)at 73F.Arcadia,Fl was the highest soil I found at 74F. Apopka,fl(central Florida)reported 73F and North Florida at Marianna,Fl.reported 65F with an air temperature of 68F.

I am certain that this is an important aspect of tropical plant and palm culture.Any idea what your soil temperature is?

[epicure3 96]

Heck ya! What good palm grower doesn't have a soil thermometer. Mine is currently reading 53F. The coldest I have ever seen it. I usually bottom out around 56 or so by mid-winter. Last month, it was warmer than normal finishing out Nov. at 66F. I imaginge it will rebound shortly with the warm weather we are having. I have my sensor about 1' down into the soil in full shade in the coldest part of the yard.

[_Keith 775]

I am only concerned about one temperature. The one at which the palm dies. And I need no sensor for that, for the phe palm will tell me, although it sometimes takes quite a while to read.

[Jim in Los Altos 3,267]

I measure soil temperature on a fairly regular basis throughout the year and the temperature varies only slightly from one area to another everywhere in my yard. It's rarely more than mid 70's in the summer and right now it's averaging 54F. I do have one winter "hot spot" near my house and on the west side that is currently reading 62F and that's where my Roystonea borenquena is growing.

[Walt 1,480]

I've been consulting the FAWN (Florida Automated Weather Network) for close to 10 years now. They have a weather station about 8 miles (as the crow flies) north of me.

It was a result of using the FAWN sites that I discovered, on radiational cooling nights, just how stratified the air can get, and that just a mere 10 meters above ground level the air can be signifigantly warmer. Further, it proved to me that out here on the Lake Wales Ridge, those at elevation have a 1/2 to 3/4 USDA zone higher rating, at least on radiational cooling nights, which comprise about 95% of the coldest nights here, then areas down off the ridge.

Case in point: Two winters ago, on a cold radiational cooling night, the Belle Glade FAWN station reported a 14 degree F difference between 60 cm and 10 meters. That's a 14 degree difference in approximately a 30 feet elevational difference!

To show that that particular reading wasn't an anomaly, I also checked a half dozen other FAWN stations that night and all were showing readings of 8-10 degrees spread between 60 cm and 10 meters.

Later that same night this temperature disparity evened out some, but still showed a 5-6 degree spread within the aforementioned elevations.

I also like to use FAWN's brunt equation table, which projects the upcoming night's low temeperature based on the dew point and corresponding temperature at sun down.

http://fawn.ifas.ufl.edu/

Sebring, Florida FAWN weather station (with temperature stations at 60 cm, 2ms and 10ms)

[bubba 2,397]

And so the use of choppers in the Glades above winter corn!

[bubba 2,397]

Jan.5,2009-Ft Lauderdale soil temperature at 10 CM.=73F.

[sonoranfans 2,932]

Soil temps in gilbert AZ have been about 52F at 4" depth, and 57-58F at 10 inches in the last week, our coldest time of the year, +/- a month of the winter. Palms are are slowly growing now, with the cold hardy species showing the most activity. These soil temps are from a monitoring site in queen creek, 4-5 miles away.

Edited January 6, 2009 by sonoranfans

[bubba 2,397]

Interesting to watch the effects of cold fronts on soil temperatures in Florida. All were taken at 6:30 PM. Citra,in North Central Florida,reported an air temp. of 49F and soil at 10 cm of 56F.Further South,just South of Tampa,North Port,recorded 52F and soil at 65F.Further South, in Ft Lauderdale,temp in air was 61F and soil was 70F. I bet soil temperature effects Tropical Palms.

[gsn 22]

Bubba,

I bet your right about soil temps affecting tropical palms.

My thoughts are, this one of the main reasons they have trouble growing Coconut palms in California,even in frost/freeze free microlimates.Even though the temp never falls below freezing the soil stays to cold over their long cool fall/winter/ spring.

I think other tropical palms might fall into the same soil temp requirments, or close as coconuts! Might also explain some the yellowing in the winter of certain marginal species durning the winter even in those same frost/freeze free micro climates.

Just my 2 cents

[Walt 1,480]

I think low soil temperatures induces potassium deficiency in most zone 10B and up palms, since root activity slows down and minerals are less available to the leaves.

I know every winter my Dypsis lutescens palms' leaves get very orangish looking from potassium deficiency. When weather warms up the new leaves are nice and green.

I have one coconut palm here in zone 9b, and when we had that cold spell back in November it caused the bottom 4-5 fronds to quickly turn yellow, then orange, then mostly dead and dried. All fronds above the bottom 4-5 are perfectly green.

[epicure3 96]

Bubba,

I bet your right about soil temps affecting tropical palms.

My thoughts are, this one of the main reasons they have trouble growing Coconut palms in California,even in frost/freeze free microlimates.Even though the temp never falls below freezing the soil stays to cold over their long cool fall/winter/ spring.

I think other tropical palms might fall into the same soil temp requirments, or close as coconuts! Might also explain some the yellowing in the winter of certain marginal species durning the winter even in those same frost/freeze free micro climates.

Just my 2 cents

Your 2 cents are worth about $100. That is exactly correct. The soil temp is too cold here to support a lot of tropical palms, namely coconut to start with. Areca Vestaria and Adonidia would be 2 others. However, there are some tropical species that do just fine here such as veitchia, hyophorbe, roystonea, wodyetia, ptychosperma, etc... Some yellow, some don't. The older the palm, the less yellowing that occurs. My Hyophorbe Verschafeltii used to yellow all the time in winter but hasn't done so in the past couple even though the weather hasn't really been any different. Veitchia Arecina never yellows, nor does Roystonea. My soil temp is 60F right now in the coldest, shadiest part if the yard.

[bubba 2,397]

With cold front in play today it is interesting to watch:

Citra-air/soil-41/50

North Port- 57/67

Ft.Lauderdale-64/68

9:49 AM/EST