There is more to citrus hardiness than “hardy to 16F.” Here where satsuma can be grown unprotected in the ground near Houston “hardy to 16F” means 16F for a few hours, not 80F the day before, and not below freezing for 24 hours or more. No citrus is hardy to 16F for 24 hours. In 1989 we had a freeze lasting 4 days and a low of 10F. All unprotected citrus hardy or otherwise was frozen including the rootstock.
I’ve tasted most of the “cold hardy” citrus and they taste awful. Citranges(orange x trifoliate) tastes like battery acid. I had a few dozen of citrange this year for seeds to grow rootstock. Just the smell of them when harvesting seeds made me gag.
Here is a typical comment for “cold hardy” citrus fruit: “The fruit should carry a warning label: Caution you are not really being poisoned - it just tastes that way.”
In my experience yuzu is not more cold hardy than satsuma, there is little to no juice, and are full of seeds. I used to have an 8+ foot tall bearing yuzu on flying dragon. Chopped it down as I never could figure out what to do with the fruit.
Trifoliate orange tastes particularly bad. It also has a resin that coats your fingers that can’t be removed with water. It takes rubbing alcohol to get rid of it. Again hardly any juice and 50+ seeds per fruit.
The “frost” series has not proven to be very cold hardy in practice, certainly no more than satsuma, the most cold hardy of edible citrus. It has been sold in the DFW z7 area and is a good seller because it is repeatedly frozen and killed.
From my website: Is Cold Hardy Citrus a Myth?
Since I’ve built this website several people from the Seattle, WA area have contacted me interested in growing citrus in the ground. After all they are in zone 8(northern) aren’t they? Hmm. They have been reading about cirus covered with snow and thriving in zone 7! The morton citrange tastes like a tangleo and can be eaten out of hand! You can make marmalade from trifoliate orange fruit! There are not many sources of information available describing how the fruit of citrus rootstock varieties (“cold hardy citrus”) tastes as few people are actually brave enough to taste one.
I quote from the book “Citrus for the Gulf Coast” by J. Stewart Nagle: Swingle citrumelo=>“fairly juicy but juice sour and very bitter with strong astringency and gum cells to carry flavor.” Morton citrange=> Although the fruit looks like an ordinary orange, it has much worse flavor. Juice cannot be diluted to obtain satisfactory flavor, but the fruit may be consumed with a grapefruit spoon , if one is careful to not scrape too many astringent oil droplets off the section walls." Citrandarin=> moderately juicy, juice with sour trifoliate-mandarin flavor, somewhat bitter and astringent. Phelps citrange=>“The fruit should carry a warning label: Caution you are not really being poisoned - it just tastes that way.” US119 or “Snow Sweet”=>"juicy with a moderately sweet orange flavor, but with and unpleasant, lingering bitter trifoliate aftertaste. Not as sweet as Morton citrange but more attractive and with much less “bite.” I don’t know about you but I prefer citrus fruit that doesn’t have a "bite." Ichang lemon=>“very juicy, juice sour but insipid, without much distinctive flavor.”
To my taste, the thomasville citrangequat is the closest of the “cold hardy citrus” hybrids to edibility. However fruit from the seedling tree I have tastes horrible so I found a better selection and grafted it to my tree. The juice from my seedling thomasville could not be sweetened with any amount of sugar. However, even with the better selection of thomasville, most people wouldn’t eat it. I have heard some of the amateur citrus hybridizers of Houston say “there are cold hardy citrus and there are good tasting citrus but there are no cold hardy good tasting citrus.”
I have tasted many “cold hardy” citrus fruit at the Galveston county citrus show held in December. I have yet to taste one that the average person would eat willingly. After tasting a rangpur lime my wife rushed to the drinking fountain desperate to get the lingering bad taste out of her mouth. One of the fruit judges at the show told me that most of the various cold hardy hybrid citrus he has tasted would make you gag. I have tasted the carrizo citrange, ichang lemon, rangpur lime, and many others and they were either too sour or without citrus flavor. The changsha mandarins I have tasted gave you a mouth full of seeds with every bite. Trifoliate orange fruit is definitely inedible and one would be dreaming to think you could make marmalade with it, it is so full of seeds there isn’t a teaspoon of pulp per fruit!
My experience with citrus cold hardiness: I had a mature satsuma mandarin and nagami kumquat in the ground in 1989 when the Houston, TX area (zone 8b/9a) experienced freezing weather for 96 hours with a minimum temperature of 10F, a 100 year freeze for our area. This freeze killed both trees deader than a doornail, even the rootstock never recovered. Kumquat is supposed to be among the hardiest of citrus able to survive 10-15F when dormant. Hmm. This year we had a late freeze in March with a temperature at my house of 25F as recorded by my remote digital thermometer. My meiwa kumquat was damaged on 2 out of 3 limbs and nearly died and my satsuma trees were defoliated. A friend who has been growing and budding citrus for 30 years reports that in the 1989 freeze “all unprotected citrus, cold hardy or otherwise were killed” .
Do you get cold weather like this in your zone 7/8 area? If you do, what do you think your chances are of growing citrus outside? I went to the University of Washington in Seattle for 4 years and remember that Frosh pond froze over solid for several weeks one winter. Hmm, doesn’t sound very citrusy to me. Do you have hot weather in the summer? Do you have to wear a light jacket at night in the summer? Citrus won’t grow until the temperature reaches 55-60F at a minimum and need 90s weather to sweeten the fruit.
Citrus can survive prolonged freezing weather if protected. What do I mean by protected? You can cover them with a tarp or blankets and put a heater underneath or you can bank the trunk to above the graft with dirt. The dirt will protect the graft from freezing but the top will be frozen. When spring arrives, cut the frozen parts away and the top will grow back rapidly. This is how meyer lemons (hardy to 24F) are protected in my areas. I have seen mature 15 foot meyer lemons trees banked, the top frozen, t top cut off and by fall be 6-8 feet again to fruit the following year. We occasionally get a few hours of 18-20F but didn’t have that cold of weather between 1989 and 2002.
Citrus trees can survive cold weather if dormant. Where I live on the Texas Gulf Coast, we often have warm spells on and off again all winter long. These warm spells can cause citrus to grow actively at just the wrong time because a “blue norther” cold front can blow down from Canada at any time and freeze us out=>dead or damaged citrus trees. One thing that can help is not fertilizing your citrus trees after June 1. Without the stimulus of fertilizer, a citrus tree is more likely to stay dormant all winter. I know of a sweet orange in a vacant lot in Beaumont, TX that has survived some freezes, however it is neglected and gets no fertilizer or irrigation and is close to the Neches river and a Refinery=>maybe a heat island?
If you read this and think “cold hardy citrus” taste good or have unprotected citrus trees with supermarket quality edible fruit survive outside in zones 7 please post your comments in my guest book.
Stan the Citrusman of coastal South Carolina says:
I have been growing satsumas for 20 years outside/in ground and have seen some brutal temps in that time period…I do take precautions to protect my trees when the temps are to be in the low teens but so do the citrus growers in the citrus belt… I pull out the plastic on an average of once a winter… Not a bad trade off considering the reward I get when my satsuma trees bear a bumper crop. Agreed, some of the citrus species you describe may not be grocery store quality. Still for someone outside the citrus belt, the sight of a large citrumelo or ichang lemon tree, loaded with fruit is reason enough to grow them… There is also a tangerine tree of unknown origins that grows here in Coastal SC that I will put up against anything you can grow on the Gulf Coast… This tree bounced back from the Christmas freeze of 86 that wiped out most of the Central Florida groves… It has been constantly producing fruit since the early 90’s and has never been artificially protected in any form or fashion…I have photos and documentation to prove it… My point is that if people outside zone 9 want to experiment with growing citrus let em have at it… It can and is being done. No myth here.
Stan reports that he is zone 8a, about 60 miles from the South Carolina coast and 240 north of Florida. He has 4 mature satsuma trees. His area rarely experiences 24 hours of freezing weather and when they do he covers his trees with plastic. He is planting a citrus grove on his farm near Scranton, SC 29591 of citrumelos, citandarins, ichang lemon, a row of satsumas and his favorite hardy tangerine.
Larry the Citrusman of Vancouver, BC
Larry replies at his success after I sent him thomasville and sour orange seeds last fall:
All the seeds you sent me did sprout and seedlings are doing great! In fact I planted out some of the thomasville citrangequats into a cold frame to over winter with protection and have kept a number to remain in my greenhouse as well. I’m hoping that I will have a reasonable survival rate on the cold frame seedlings as it doesn’t really get all that cold here in the winter but still need to hedge my bets though. .My seed grown Poncirus has finally produced 1 lonely fruit this year after being in ground from seed planted about 8 years ago. Citrus sure does take its time to produce fruit doesn’t it! Am also trying a Carrizo outdoors with protection as well as a Owari Satsuma on Poncirus rootstock… not sure how they will do but we will see. If you find any other seeds that you think would be worth trying up here I would love to test some more as I seem to be only 1 of about 2 or 3 people in all of Canada that are experimenting with hardy citrus varieties. Best regards, Larry B.C. Canada V7C4G2
John of Lake Jackson, TX with over 100 citrus varieties in his back yard and a citrus hybridizer say:
Well you know how to stir the pot with your cold hardy citrus web site. Ha Ha But it is true. I gave up long ago with the cold hardy stuff and just decided I want good tasting stuff. On that note I would go easy on ordering a lot of indio mandarinquat. It is more an ornamental than something I would like to eat a lot of. We dilute it with other fruits in a fruit salad. I have talked to Dr. Brown ( Dr Brown is a citrus hybridizer who has been making crosses for 50 years ) and he told me that even with the first cross with trifoliate the cold hardness drops significantly and f2 and f3 away from trifoliate make the tree even more tender. The other problem is you can not use trifoliate as the mother because it does not produce hybrids. (There are claims that there is a zygotic producing trifoliate, but I don’t know who has it.)