I'm in zone 7b, Raleigh NC. Outdoors in the ground I have a huge Poncirus (came with the house), two Citranges - one of which has been in the ground for a couple of winters, one is on its first year in the ground; two Changsha tangerines - one of which is new and one that has been in the ground for a couple of years; two Ichang Lemons - one of which has been in the ground for at least one winter, the other one is new.

All the plants that have been through a winter have suffered except the Poncirus and the oldest Citrange. The citrange was given to me. It had a hand written tag on it that looked like it said 'Dalton'. It does not appear to be grafted. It has bloomed once before, but only a handful of flowers and never set fruit. It has thorns that I swear are over 4 inches long. I have these guys planted in a sheltered spot beside the garage with a Southeast exposure to keep them out of cold wind in the winter. The last two winters have been pretty mild and still most of them have suffered.

The poncirus is across the yard out in the elements and is unfazed by weather.

Scott, what do you do with your satsuma in winter?

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Bill, I build what amounts to a cold frame around it using filled 35 gal water barrels covered with a layer of 6 mil poly sheeting for the walls and an old glass door for the roof. Water has a high heat capacity and releases quite a large amount of heat at it's freezing point . It therefore acts as a heat reservoir to take the edge off of the coldest nights and moderates the interior temperature. I am able to overwinter the tree without supplying any additional heat. The lowest interior temp all winter was 27.5F, technically a zone 9B winter (but of very long duration). In the future, some external heat to keep the temp above freezing will be necessary. I now have a Gold Nugget mandarin, which is a very late ripening variety, so I will have to overwinter the fruit.

The setup:
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The red power cables are for the emergency heating system, that was set to turn on at an internal temperature of 27F.

Here's some data comparing the inside vs outside air temps from Jan., our coldest month last winter. There was a stretch of ~8 days when the outside air temp did not get above freezing.
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A picture of the satsuma from ~3 weeks ago, the fruit are larger now, see original post. (the Gold Nugget is cut off on the right)
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Trianglejohn,
How are the Changsha's and Ichang Lemons, have they ever fruited for you, and do you have any pictures? I have thought about trying both of these at various times and would be curious to see what your trees look like.

Although not very common, P. trifoliata is reliably hardy up here in MA, I know of 7-8 trees, two of which are over 30 years old and have survived lows of at least -10F.

I've always wanted to try something like this but I'm afraid I don't have a sunny enough spot on my property for an in ground citrus. I look forward to seeing more pictures of your trees Scott!

Kris

Kumquat zone 7 north ga

Scott - I'll try and take some photos this weekend. I only got those two varieties because other people in this area rave about them. Mine are tiny and will take years to get to fruiting size. In fact I believe some of mine have gotten smaller after the last two winters (which were mild). People say they that Changsha is sweet but seedy and that Ichang Lemons make the best lemon pie. I've never tasted either of them.

I started out with a few tiny one gallon lemons and limes. They did so well and grew so big that I now have a 20 by 30 foot hoophouse/high tunnel that I seal up like a greenhouse in the winter and heat with a wood burning stove (firewood is free). It is stuffed with all sorts of tropical fruit trees including a lot of citrus and those original plants that are now head high. Because I get a decent crop off them I don't feel the pressure to have in-the-ground citrus fruiting all the time. My outdoor collection are simply a test. I hope they eventually bloom and fruit but it doesn't really matter to me.

Hmmm wonder if I could do water thing on my balcony

Last year I purchased two dwarf citrus trees. One is an Improved Myer lemon and the other is a Mexican lime. I planted them each in 2-ft deep pots at least 14 inches across at the widest point and left them outside this past winter. I wrapped them with a double layer of bubble wrap in the form of a tee-pee. and placed a 40 Watt bulb on the ground of each one and left the light on 24-7. I just removed the wrap on 4/6/14 guessing that we are finally past any possibility of a cold snap. The lemon tree was fine, but the dozen lemons on the tree when I wrapped it were shriveled and looking like they molded. The Mexican lime had die-back on several limbs which I cut off.

Having grown up in Southern California I understand their fruiting process and so I know that the lemons I lost would have been ready for picking later this year. Boo-hoo. I see the start of new blossoms and so my concern is what is the best way to over-winter citrus in pots outside? I should mention that I live in West Seattle and yes we do get lots of rain, but not the light misty type we got when I first moved here back in '69. It comes down in torrents. Seattle winters are cold with only a few days of below 30 degrees.

This coming winter I want to try something different because I can see that the amount of water I gave the trees might have been too much for the Myer lemon, but not enough for the Mexican lime. I only watered them twice. Because of our very low-light winters and the moldy lemons I am thinking that I need to wrap them in something that can breath, keep out the frost and let light in. I do not have a garage. Any ideas would really be appreciated. I'll try 100 watt light bulbs and maybe some crumbled newspaper to help deal with the moisture. I can't drag them indoors.
Thank you.

Congrats Scott, you're the first person I've heard of achieving that much of a zone jump relying on solar heat! And in a less than ideal climate for it too...

I've been contemplating something like this for years, I guess now I have no excuse! It should work very well in my climate, after all this is how I heat my house!

If it would not cut down too much on your light inside, you might try painting the barrels black for maximum solar gain...

That's a really clever idea Scott. Was the container airtight, or did you leave a lot of gaps? I'm wondering how you avoided solar cooking on Sunny afternoons, or mold etc. from a lack of air circulation?

Scott, can you e-mail me if possible..I could use your help before fall. I looked for your contact but you have none...Please...Thanks a million!

mikerno_1@yahoo.com

8 foot tall seed grown sweetlee tangerine tree in ground is 2,5 years old from seed sprout

greenhouse top view. Roof and west side are quadruple glass.

south and east wall are 2 layers thick.

The green house goes up in October and comes down in may.