All Things Cold Hardy Citrus, news, thoughts and evaluations


#101

Can’t be sure but Kaffir limes and others papeda are Zone 8 fruits.


#102

Re: “kaffir”, I’ve heard that “Makrut” is the politically correct name now. Better than kafir/kufr.


#103

I do not mean to digress. For those who do not know, Kaffir is a profoundly offensive term to call an African man in South Africa. I did not know this until about a year ago.

The word Makrut is often used instead. It pronounces “ma-kroot”.


#104

I went by the tree in north Birmingham Alabama today and was given permission to grab a few mature fruit. The smell was similar to trifoliate orange though the fruit was the size, shape, and color of a ripe orange about 2 1/2 inches diameter. Flavor was distinctly bitter with the sharp flavor of a grapefruit. Each fruit had about 10 seed. The fruit had the sticky resin typical of trifoliate orange. The tree was not covered in spines, however, the tips of the limbs were distinctly sharp. From the look of the tree, I suspect it was damaged by the 22 degree weather we had in mid November. The tree had a very heavy crop of fruit this year. Based on the combination of characteristics including cold tolerance, bitter grapefruit flavor, and tree form, I think this is most likely a citrumelo or from very similar breeding. I have about 50 seed which will be planted tomorrow. I figure the resulting seedlings have potential either for fruit or as rootstock. I am aware of the tendency of citrus to produce apomictic seedlings.


#105

This makes sense. I was surprised when you said there was an “orange” tree in AL. Here in 9B we grow Washington Navel, and I know they don’t do well below 26° or so.


#106

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.)


#107

@mrtexas
Do you know a thing about , Dragon lime ?
Specifically , how much cold it can handle ?


#108

I know the finder of dragon lime, Bonnie Childers of Lumberton,TX. It is a citrange and should be quite cold hardy. I used to grow out thousands of flying dragon seedlings every year. On occasion I would get a “dragon lime” which is an unknown hybrid of flying dragon and some edible citrus. IMHO dragon lime is inedible. It is the size/shape/taste of other citranges. I would also occasionally get a tiny dragon seedling.

Dragon lime has much more contorted branches and limbs than flying dragon trifoliate. Fruit is like other citranges.


#109

The dragon lime I have tastes good,( from Stan)
Just wonder how hardy ?
Do you know what temp. It has endured?


#110

Haven’t had a citrus low temperature here near Houston since 1989. “Cold hardy” citrus hard to find in the area. Most of the people who made the crosses are dead now, an older generation. Can easily grow navel oranges and grapefruit here now. In 1989 we had 10F and frozen for 3 days thereby killing nearly all unprotected citrus including the rootstocks. I lost my large satsuma and kumquat trees. Citrus on trifoliate rootstock not available commercially anymore, all are on fast growing citrange. Didn’t plant citrus again until 2000. I wonder the gene line of your “dragon lime.” I sold a dragon lime seedling to Tom McClendon in St Marys Georgia many years ago. Don’t know if Bonnie Childers ever sent anyone budwood. Tom wrote this pamphlet. http://neo6601.free.fr/Pdf%20-%20Doc/Hardy%20Citrus.pdf


#111

Don’t know gene line , but I got it from Stan – Sc.
May be from yours ?


#112

I think that the only way a truly cold hardy citrus would ever exist is with a very long ongoing hybridization project, finding citrus plants that could change the timing of fruiting, of dormancy, the timing of coming out of dormancy, finding citrus plants with cold resistant wood and cold resistant roots and so on, then hybridizing them together, to gain the cold hardiness, then would come the hybridization to make the fruit as desired.


#113

I don’t believe most citrus (at least more warm climate citrus) ever go into a true “dormancy” I know all mine produce flowers and foliage year round.


#114

There are plenty of citrus that people pay no attention to because the fruit is not desirable, or for other reasons. DNA mutations can do some odd things, also the climate of origin does not always mean anything. Malta a place that never hits freezing temperatures for more than a few minutes, some of the most cold hardy figs come from there. University hybridization projects often studies over 1,000 varieties of one type of plant. I doubt that a person like you or me could manage to find such a thing.


#115

It would be nice for some of our chillier neighbors to find a true edible cold hardy citrus.


#116

Maybe if some university, in lets say the state of New York were to plant enough lets say manderine orange seeds outside, maybe some of them could gain a DNA mutation(s) that adds strong cold hardiness. That’s how plants often gain disease resistances.


#117

A similar paradigm played out with apricot with several thousand seedlings planted and 3 or 4 found to be cold hardy. Citrus will be a different concern given the genetics involved. I suspect the next 30 years will see some work done in cold climates and there will eventually be edible citrus at least through the southern half of the U.S.


#118

Citrus on trifoliate orange root stock does have bark stop slipping after a couple cold fronts ni the fall. BTW trifoliate orange is the most cold hardy citrus although fruit is awful. Trifoliate loses it’s leaves in the winter and can be grown north of the Mason Dixon line. The problem with trifoliate crosses is that the awful trifoliate taste lingers as the cold hardiness diminishes. 1/4 trifoliate crosses like thomasville citrangequat tastes awful even though it is relatively cold hardy. I can still remember the thomasville tree I brought home from a plant sale. It had fruit on it and when I tasted the fruit it was so bad I thought I had been swindled. Why would the master gardeners sell such a tree with inedible fruit on it at a fruit tree sale? Citrange is next in cold hardiness which is a cross of trifoliate and round orange. Swingle is also hardy which is trifoliate crossed with grapefruit. Edible citrus on either of those two as root stock is not cold hardy as citrange and swingle both have hybrid vigor. Making crosses for cold hardiness has been going on for 100+ years and still nothing. In the 60s and 70s there was a bunch of interest in making “cold hardy” citrus crosses in the Houston area. Since 1989 though no citrus killing freezes here. The most cold hardy desert quality citrus are satsuma and kumquat. They can survive several hours of 20F or less freezes without harm if preceded by cool weather. A month of 80F and a night of 20F can cause freeze damage however.


#119

Push the Zone by David the Good (which is an excellent read if you want to grow citrus in less-than-ideal zones btw) had an interesting anecdote about this. While he lived in Tennesse he learned that someone allegedly had a cold-tolerant lemon, and that they had apparently gotten it by planting tons of seeds for years until a seedling survived. He got a seedling from it from someone who knew the guy, but it perished in the Nashville floods. David left the state in a huff not long after because the local HOA rubbed him the wrong way, and he forgot about the lemon until much later. Assuming it survived the flood better than its seedling did and isn’t a misidentified Trifoliate there may be a truly hardy lemon in Zone 7 Tennessee. This is all an anecdote of an anecdote, so take it with a grain of salt, but at the very least it’s a neat story that has inspired me to try something similar with citrus that are already fairly hardy. You never know what kind of interesting mutations plants can show!


#120

Here are the Triofoliate poncitrus orange seeds are growing. Thanks to Lord Kiwi @lordkiwi . Hopefully they will put on some size then going to tge ground in late May for Z5 trial.

Tony