Some aspects of this topic have been covered previously but I thought it was worth starting a new thread since I wasn't able to find all the information I needed.  According to the weather forecast we are supposed to get an arctic blast on Friday in the northeast and mid-atlantic.  In my area they are predicting a high of 20 deg. F and low of 9 deg. F.  I could be wrong but I don't recall it getting into the single digits in the 3-4 years I have been growing figs and this has me concerned. 

My dormant figs are in an unattached garage with a dirt floor and no heat source (and no electricity).  They did great last year but it was a milder winter.  It would be easy to bring the 2-3 gallon figs in the house and put them into our coldest room (around 60 deg. F) but the others are too large.  I am assuming that bringing them in for a day or soisn't going to hurt them even though they will quickly undergo a large temperature change - correct?

For the figs in larger containers I'm looking into getting one of those space heaters shaped like a radiator that have an internal oil reservoir.  The goal would be to raise the temperature in the garage around 10-20 degrees (say from 15 deg to 30 deg).  I would have to bring an extension cord into the garage.  I read that you are not supposed to use extension cords with these because of fire hazards, or if you do then use a very heavy duty cord.  Does anyone have advice on this - I don't want to burn down my garage with the figs!  Also these space heaters are designed for indoor use at higher temps e.g. to raise the temperature from 55 deg to 70 deg.  Is it a problem to use them at low temps like I am proposing?  I know you can get thermostats that will turn on the space heater when the temp reaches a minimum (like 30 deg) but at least for now I am planning on only using this for extreme lows maybe 2-3 times per year so I want to keep it simple.  I'll just turn it on for 12 hours at a time at a setting that will raise the garage temp a few degrees.

Thanks in advance for your input and happy new year!

Im buying a DuraHeat 23K btu kerosene heater from Home Depot  on the way home tonight.
My figs are in an unheated garage as well and up to this point the lowest temp its gotten down to was 27F.
I really dont know what the minimum temp potted figs can stand is.

Another option may be to put the heater on a timer and have it turn on for 15-30 minutes every hour or two.

I used that type of heater recently while making sausage in the garage and the extension cord and heater cord both got very hot.

The kerosene heater would solve my extension cord issue but it is a pricier alternative.  Also I have no idea where one would buy kerosene.  Does HD stock it too?

So far my garage has been down to the low 20's and the figs look fine but I wouldn't want to push it much further than that.

If you don't want to heat, just make a chicken-wire cage around each one and fill it with straw or chopped leaves. Or even wrap them in carpets, anything to insulate. After insulating them, pull them into the sunshine for the day, then back into the garage before dark. My understanding is that should be enough for most figs.

If you do use the space heater, please be extra careful and don't let it run during the night. Way too many houses have burnt down from unattended space heaters. All it takes is a 'coon come messing around looking for that warm spot and your garage is toast.

I think I'll at least spread some straw over the top of the pots.  I hadn't thought about an animal knocking over the space heater. I've heard that some space heaters have a feature that shuts them off when they fall on their side. 

You are not that far from me, can lend you a Kero heater if desired.  Safer Alternatives to electric heaters are heat mats under your pots or a large barrel of water next to or around the figs  with a farm heater in the water, the water gets warm then acts like a large radiator all night. Old fashion HW stores and farm supply stores sell water heaters for chicken/horse and pasture waterers.

If were talking about a few degrees, maybe a heat lamp like what is used for chicks?

Calvin, that is a good idea too.  Probably with 2 or 3 of these I could project enough heat at the containers to keep them from getting too cold.

http://www.amazon.com/DeLonghi-EW7707CM-Safeheat-ComforTemp-Oil-Filled/dp/B000TGDGLU/ref=sr_1_1?ie=UTF8&qid=1388516717&sr=8-1&keywords=oil+filled+electric+heater

anti freeze setting, shuts off if tipped over, metal is not hot enough to start a fire.  The Q I can't answer is will you need 1 or 2?

http://www.statelinetack.com/item/k-and-h-ultimate-pail-heater/E000343/
in a 30G barrel of water, my water temp averaged about 55 degrees during a week of 15 degrees, kept the area around the figs above freezing

If you scroll down to the chart of length vs amps you'll see that a 25' or 50' cord with 10 G wire will easily handle 20 Amps.  These oil heaters max out at 15 Amps.  Even 12G wire will handle 20 Amps

http://www.homedepot.com/c/factors_to_consider_when_choosing_extension_cords_HT_BG_EL

$30  25' 12/3 cord

http://www.homedepot.com/p/Husky-25-ft-12-3-Extension-Cord-AW62614/100661446

Or cheaper or more feet at the same price if you're a prime member.

http://www.amazon.com/s/ref=nb_sb_noss_2?url=search-alias%3Daps&field-keywords=12%2F3%20extension%20cord

I personally like Jacks suggestions. I have more than one farm store nearby that have those watering bucket heaters.

I will be using something similar when I get my greenhouse built. I have some old aquarium heaters for larger tanks (55 gal+) that should work pretty well in a 50 gal plastic barrel. I also have one of those heaters that attaches directly to the top of a propane tank (BBQ grill size).

Just some other ideas to consider. 

Jack also mentioned to me the idea of a bird bath heater that would dip into a 55 gallon barrel with water.  It so happens that I have one of these in my garage filled with water to moderate the highs and lows.  So this might be the best way to go from a safety standpoint.  I also still like the radiator that Bob has linked to since we need one for the indoors anyway.

You might want to consider Eliot Coleman space within a space style protection. He uses floating row cover supported by small hoops inside of high tunnels to get 10-15 deg protection for growing veggies. Laying the pots horizontally to bring the trees closer to the ground (the biggest heat source you will can have) and covering with a tarp would buy you at least a few degrees. If you could keep a few inches of air space above the pots and trees with hoops or 2x4s or something, even better. I would be very cautions about heaters and lights, especially in combination with tarps. A more passive source of heat would be to fill 10 five gallon buckets (milk jugs, or whatcha got) with hot water and placing them among the trees. Not something you would want to do everyday, but 3-4 times a winter would be a cinch.

I'm not a source of fig care info, but I do know about electricity.
If you go with an electric heater, a few things to consider:

1. Make sure you use an adequate extension cord. The longer
the cord, the larger the wire size needed. 12 gauge is good for
50 to perhaps 100 feet, depending on other factors. 10 gauge
is sufficient for any reasonable length, if used correctly.

2. When using an outlet for a heavy current load, especially an outdoor
outlet, make sure the outlet and cord plug are in good condition with no
visible corrosion. Make sure the plug makes good positive contact in the
outlet. Sometimes it is helpful to slightly splay out the plug contact
blades to give extra contact pressure. It's a good idea to check the area
around plug connections for localized warmth after the heater has first been
run for an hour or two. 

3. Don't cover up any part of the extension cord with anything that could
insulate it while it is being used. Don't pile up excess cord in a small compact
pile. It could potentially create a hot spot that takes a long time to build temperature. 

4. If the heater used has a lower power setting, the current
draw is in direct proportion to the wattage used. A lower power
setting is much better from an electrical standpoint if it is 
sufficient heat for the the purpose. If the heater has a 700 watt
setting (most do), that would the setting to use, even if continuously,
if it provides enough heat. 

5. If this was an installation that was marginally served by
extension cords because of the wire distance or the amount
of heat required, upping the voltage used from 110/120 to
220/240 (like a welding/dryer/range socket) can provide twice
the power over the same distance and wire gauge. Most likely
this isn't a consideration for your application, but is worth 
considering any time a heavier wattage load is installed.

Jon just posted a potted figs link a week or so ago, something published in England maybe, it states potted figs shouldn't get below the mid 20s. My garage is detached and unheated-I am going with the oscillating electric heater attached to heavy duty extension cord, fire hazards and all. I may bring in a couple of smaller pots. Get ready folks!!

Rewton

The one thing I'm thinking about is that this is a one or two-day overnight low. I don't think you need go spend exta- ordinary costs or measures for one or two nights.
I think ANY type of heater in your garage will be good, even if you heat up hot water in a few barrels or jugs to raise the temp at dusk. It's a night or two of cold temps ( for now ).

bada_bing and Bob, that's the sort of information I was looking for with respect to the extension cords.

I use the an oil filled radiant heater fed by an outdoor extension cord and a thermocube. The heater is turned on as temps drop below 35 degrees, the cube turns on and fires up the heater. If the GH reaches 45, the cube turns the heater off. Don't be afraid to use the cord. Just make sure water cannot get in the cord. My GH is only 16' from my deck which is where the power is.

Oh, and I just packed in my 2 large Beall trees an White Marseilles in my garage. Can't loose these guys!

and Sultane........don't wanna lose him either!

Group your trees into a small area, cover them all with a cheap, plastic drop cloth, and place some strings of Christmas lights, with bulbs, around all the containers.  The heat from the bulbs will warm the trapped air around the pots/containers, branches, and the drop cloth will contain the added heat, and create a warmer micro-climate around all the trees.  It's quick, ugly, temporary, and CHEAP.  You probably already have the heat source....the Christmas lights.  If you don't, they are probably 1/2 price, now.  The cost of these running these lights is just pennies/day.  No fumes, no blown fuses, no fire hazard.

Hope this helps.



Frank



EDIT: 

Has anyone ever used these exothermic, chemical heat packs/hand warmers to heat a container to prevent damaging, hard freezes?  Just wondering if these gel packs might have a use for "defrosting" fig trees......

I'm a electrician and I couldn't have said it better than bada bing did!!

This morning the temperature in the garage was 26 deg. F and dropping (with an outdoor temp of 14 deg.).  The outdoor high is supposed to be 22 deg today with a low of 9 deg. tonight.  To be safe I brought my 1 year old Bl. Madeira and Figo Preto in doors.  The rest of the figs in the garage are in 5 gallon containers or above and tend to be cold hardy varieties.  I also piled up snow around my Kathleen's Black and Sicilian Red in-ground trees which have been wrapped to varying degrees.  I went ahead and ordered a radiator (oil) type of heater and 12 gauge cord as per the suggestions above.  They are supposed to be delivered this afternoon.  If case delivery is delayed due to the weather I shoveled snow up against the walls of the garage.  A couple days ago I sprayed the expandable insulation foam stuff in all the gaps along the foundation of the garage as well.  It will definitely stay at least 5 degrees above the outdoor temp no matter what.  Time will tell.