I'm starting with super market lemons for that is all I have to work with

Okay but I'm still taking supermarket lemons and pushing them to take the cold each year leave them in the cold longer for cold hardy genes has to come from struggle not comfort of the the tree that way over time the cold hardy genes will surface so I can push them through watching how my trees preform

Howard, re your statement: "cold hardy genes has to come from struggle not comfort".

You are talking about selection for cold hardy genetic mutations. Genetic mutations of any gene occur at the rate of about one in a million every time a plant produces a seed. In order to come up with a cold hardy citrus, you would have to plant millions of seeds. Developers of citrus strains have increased there chances of getting a desired strain by increasing the genetic mutation rate using ionizing radiation (like X-rays and gamma rays).

So, OK, the chances of getting a cold hardy strain using your method is very low, go for it anyway. You may hit the jackpot. I wish you luck.

Let us know how things turn out.

I will but the plant has to struggle for the mutation to happen naturally

out. I am not going to pay the price those California bud wood suppliers are charging for out of staters. So, disregard my post. I am glad that I don’t need anything anymore. I live 19 miles from the closest post office, so this will help me a lot.

No, the mutation happens spontaneously, if it happens at all, and if the plant survives the struggle (from too cold temperature, or whatever) because of the mutation, then you have something.

It's very (exceedingly) unlikely a plant meant for zone 10 is going to suddenly develop a mutation and suddenly be able to survive zone 6.

A species may be able to move north over time, over numerous successive generations, but it's not going to happen all at once.

For example, if someone raised a thousand seedlings from a plant in zone 10 and saw which ones survived well in zone 9, then from those selections, planted another thousand seedlings in zone 8, and so on.

Many varieties of citrus will be all the more difficult because the majority of the seeds are nucellar, genetic clones of the parent. So it is important that you do some research. Otherwise you might be growing many times the number of seedlings you need to.

All this is of course theoretically possible, but you can see how it would be very difficult, and not pragmatic for one man.

"A thousand" seedlings was just an example. That's probably an understatement, if you're not starting off with hybridization with a hardy species like C. ichangensis or trifoliata.

It's not just exceedingly unlikely. There are several multiple levels of exceedingly unlikely, making this tantamount to impossible.

If someone was actually serious about this, I would help provide further information and advice, but it is obvious HOWARD Martin is being obtuse.

I'm not obtuse I'm just determined and focused

HOWARD Martin It is a hobby and hopefully an accomplishment for you so keep up with your plan. I am doing citrus things that is considered a waste of time. Its a hobby.

Steve

ok

Iwill be pushing Eureka lemons to that direction

HOWARD: Hope and stubbornness will not make it so. Knowledge and research will help a lot and give you some direction. I believe your main premise is wrong. So there's that. It's not the struggle that causes the mutation, rather the mutation that allows survival during the struggle. The mutation happens first (if at all). Again though, as Socal said, because most citrus tend to produce clones of themselves in their seeds, you're going to get identical genetics, characteristics, cold tolerances, etc. in the seedlings.

However, on the bright side, no matter how many failures you will experience, you will learn how to grow citrus.

US-852 (which is a Changsha x trifoliate hybrid) is probably one of the other rare cold-hardy hybrids that at least have a chance of growing in zone 6 (zone 6b to be more exact) if planted in a warm spot up against a wall protected from wind.

There's a YouTube video here:

https://www.youtube.com/watch?v=wVOHSHgMDVc

This guy can apparently manage to enjoy eating the fruits. He says they are pretty good compared to other trifoliate hybrids, although they still have some off trifoliate taste.

(Probably most people would not enjoy these fruits, but they might be considered borderline edible for the more adventurous)

I have three US-852 seedlings.

It was conventionally considered a rootstock variety.

US-852 can survive zone 7 A for many years in a protected location — at least until the next polar vortex with sustained cold temps, daytimes below freezing, and drying winds. But it cannot be considered bullet-proof even in zone 7a.

In theory, development of cold hardiness could occur in a number of ways:

1. Genetic introduction via hybridization, followed by subsequent elimination of undesirable genes. There has been progress made using this approach, but there is much more to be done. Edibility has consistently been a challenge, early ripening would be a must in cold areas.

2. Introduction of genes for cold hardiness by genetic modification, (unacceptable to many). Although strongly condemned by many, it may be the most practical and economically justifiable methodology.

3. As suggested, sowing huge quantities of seeds of cultivars with accepted taste. Then progressively exposing each subsequent generation to harsher conditions. This is human intervention and assistance of a natural process. This is a protracted, expensive process requiring the commitment of multiple generations of dedicated plant breeders keeping their eyes on the goal.

In summary, there is much potential for cultivar development. But there are also formidable obstacles. Nucellar embryony, unacceptable flavors, failure to ripen in a timely manner, pollen or ovule sterility, all remain challenges.

I am very familiar with the entirety of the situation, and I believe it definitely should theoretically be entirely possible to breed, hybridize, and develop good tasting citrus that can easily grow in climate zone 8 farther north or climate zone 7 in the South, but there would be a lot of challenges to that. This is the type of thing that would require an intense deal of investment, and probably require selective breeding over several decades, probably from multiple projects in different climate areas cooperating with each other.

Genetic engineering should certainly be possible, theoretically, but I am not aware of a single instance in the field of cold hardy citrus involving genetic engineering. Perhaps because it is so expensive and requires a great deal more expertise. This could be an area very ripe for future research. It seems almost all the current research efforts right now are focused on fighting citrus greening disease.

spontaneous mutations happen for better survival in conditions to the environmental conditions as well for adapting to new environments this comes through struggle as well because the tree wants its offspring to survive in conditions where it could not do well but only a few will reach that change and that is all It takes each Time a few are slightly different just look at seed size

Walt over at Tropicalfruitforum has made substantial progress in breeding/trialing/selecting US-852 seedlings. About 3 or 4 others there are also working with hundreds, sometimes thousands of plants, culling as they go. They are working toward cold hardiness first as a process of elimination, which helps keep the plant numbers manageable. Palatability is 2nd priority, reserved for true survivals of extreme cold temps. Apparently leaf taste gives a good indication of trifoliate oil presence, without having to invest years into a tree waiting to taste the fruit.

I can start with what I have available to work with even though it may seem unlikely to secede but I must try or I will get no results

True Howard, nothing ventured = nothing gained.

all I have to work with is supermarket citrus fruit right now I'm trying lemons and I got two seedlings of and unknown variety to me and the other ones I have to work with is Eureka lemons

one way is for the tree to struggle in the cold because that would be environmental conditions that is how they form the cold hardy mutations in the first place

HOWARD, Your posts would be easier to read and understand with some basic punctuation.

I'm well aware of my choice is a hard one but to me impossible is just a state of mind

I only have super market lemons to work with

Howard, try some oranges and mandarins from the store too.

if I can find them with seed

the only lemons I have to?work with is supermarket lemon s

Buy an orange

I do and around here they seedless be cause of the pandemic

Try a lime, mandarin or a grapefruit

right now I can't because I don't have the money

I know you all have more experience at growing citrus than I. For I'm a New ibe. at growing at growing citrus how did I manage to defy the the odds and get a regular lemon seedling to Survive this last March outside in zone 6b

March isn't as cold as Jan and Feb. The sun is stronger and heats more during the day and stuff retains heat thru the night. I doubt they would have survived in early February. This was also a pretty mild winter.

I'm a newbie even so I think I was pushing my luck a little bit here in Ashland,Kentucky in zone 6b

socalnolympia can you explain how I pulled off getting my lemon seedling to survive early march with temperatures in the. lower 20's and upper 10's for days and nights for days on end and the march winds and march extreme sun and it a regular lemon in a pot half filled with clay soil the pot black plastic painted gold and rested on a parking lot of aspault and near the building where my apartment is

Probably a few things at play there Howard.

First the asphalt and building will create a micro climate, block the wind and radiate some heat absorbed from the sun or leaked from the building. I have a detached unheated garage that's always warmer than outside because it retains heat from the daytime.

The pot itself will hold heat from the day so even if the air temperature was 20 the soil in the pot was likely much higher.

Temperatures that low wont necessarily kill the plant right away, Florida has frost on occasion and the trees survive. It's cold temperatures over an extended time that will kill the tree.

It was a mild winter this year, I have potted annuals in the yard that came back this year. In a typical winter that wouldn't happen.

Maybe if you dug a hole a few feet into the ground and covered with plastic you might have a better chance surviving next winter.

I live in an apartment

im starting with what I have to work with and that is super market lemons

Since it is a seed grown fruit you do realize that it may not bear fruit and seed for many years, even if the miraculous genetic transformation you seek occurs.

Howard, you might benefit by finding a like minded colleague with facilities and resources.

this is what have access to

and my resources are very meager at best

all I have to work with is super market lemons

I only got super market lemons to work with

You can, dig a 4/5ft deep hole, about 10-12ft long and wide, probably need steps. Then in that pit plant your citrus. Calamondin or whatever your looking at. Dont forget a well around the plant about 3 foot off and around the trunk. Then fill that pit up with 2 feet of mulch. Don't forget to cover your tree for the first few years (maybe3-5 years depending on the size tree you started with) as is acclimates to the cold. It's alot of work but definitely possible. And a tarp is like 15-20$ at Walmart I don't know why you wouldn't be able to protect it

Fukushu kumquat from seed in 6b.

Steve

I live in Utah zone 6b - 7a fluctuations. Last winter I grew a 6 inch tall tiny 'Prague' chimera citrus outdoors in-ground in a micro climate next to the south wall of my house. Temperatures dropped as low as 15 F. This tree was heavily mulched with wood chips and caged in poultry wire with a plastic tarp wrapped around it. From December 20 to Jan 15 I surrounded the cage with old milk jugs that were repeatedly warmed in the micro-wave around midnight any-time temperatures dropped below 20F. Not only did the 'Prague' tree survive the winter without defoliation but the citrus has tripled in size this year of 2022. Additionally I grew a 2 foot tall 'Nippon' orange-quat with the same procedure and the Nippon pushed out beautiful new growth last spring and is fruiting for me this year although it suffered some defoliation and 1/3 of the old leaves look damaged. I was able to harvest some fruit from 'Nippon' last December and successfully germinated a dozen seeds. Additionally both of these trees have survived summer temperatures up to 107F. The Nippon suffered some scorch in the most exposed leaves. I intend to continue growing 'Prague' and 'Nippon' citrus tree in the ground and espalier them against my home each winter as they mature. Due to my recent success I intend to also try a very cold hardy tangerine hybrid the same way. All of these citrus are grafted to Poncirus 'Flying Dragon' root stock. Good Luck Howard! Most of the folks bragging about growing a citrus tree in a cold zone are from zone 8 so I think growing citrus in the ground outdoors in zone 6or 7 takes effort and is something to be proud of. Keep trying! You will figure something out.

The dozen seedlings from my Nippon orange-quat are growing on their own root. Shortly after they sprouted I sank the small pots directly into the ground and they thrived against temperatures up to 107F. Their leaves are not scorching. I left them directly in the ground all summer so they would acclimate to the harsh sunlight and heat as they emerged beyond sprouts. Most seem to be doing fine. I plan to bring these seedlings indoors for the winter however, because they are only 3 inches tall and growing on their own roots. I plan to graft the strongest most aggressive seedling stock on to 'Flying Dragon' and see what happens in the future. I also have a friend who grew a Citrumelo on his south wall successfully all winter in zone 7a without protection. The Citrumelo is putting on very little growth this summer. Additionally I am aware of one Yuzu that survived all winter in a very sunny outdoor micro-climate in zone 6b without mechanical protection. It is possible with some ingenuity.