Citrus > Cold Hardy Citrus


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I think there are some members which have experiences with coldhardy citrus, but to receive answers you should ask more detailed what you are interested in. I e.g. I have a Yuzu since 3 winters in ground, froze to earth in winter after a low of - 15 C and has now recovered again or a Dunstan citrumelo seedlings two year old in ground took -13 C this winter - all survived, some with slight damages, others with none, depending on genetics and microclimate of place.

one thing I personally observed was, that C. ichangensis showed much more hardiness on its own roots than grafted on Poncirus. In direct comparison all grafted specimen died from cracks and all seedlings on its own roots survived with leaveloss. under exactly the same conditions. I will test yuzu on its own roots in future.


--- Quote ---I thought trifolates tasted pretty bad.
--- End quote ---

Don't think about the rootstock's fruit as at all relevant, you're not using those parts of the plant. The rootstock is the plumbing system for the plant, and it exists in relationship with the scion making decisions about how to interact with the movement of materials to and from the roots in relation to the vasculature of the combined plant and fruit of the scion. So the way Poncirus trifoliata does its part in this dance, with some scions, improves fruit quality, or causes the amount of sugar stored in the fruits to be higher relative to if it were grown on some other rootstock. These are generalizations about very complex systems in relation to the very complex systems of their environments, and you will not always find it to be true.

The only way you'd end up with the rootstock fruit's characteristics mattering directly is if you ended up with the formation of a graft chimera, which unless you're trying to do so intentionally is a rare occurrence. Not something you need to be worried about, especially as typically you'll cut any branches emerging out of the rootstock itself, and probably therefore also anything emerging from right at the graft union. You end up with two plants cooperating to function as one, but the rootstock is only able to interact with fruit development and formation through what it moves through the vasculature of the plant, and given that significant portions of the citrus industry both now and historically have used poncirus as rootstock, you can be relatively sure that it isn't causing those scions to spontaneously produce poncirin in substantial quantities, nor pumping anything into the scion which fills its fruit with resinous nastiness :)

You seem to want to avoid growing on a rootstock, and I don't have a clear sense of why.

To your question, luckyjimi: My Yuzu had no twig damage at an episode of a few days late spring frost around -10C while Poncirus lost a lot of twigs. -10C is probably not the limit of Yuzu. My point was that it is by no means the limit of Poncirus yet Poncirus suffered more. When we talk about hardiness then, I think, we should distinguish between frost tolerance of a fully dormant plant in the mids of winter season and frost tolerance of a plant in spring when dormancy is already broken. In my climate (sea climate at 500m above sea level under exposition of atlantic winds) the absolute minimal temperature in winter is no longer a real problem (-12C at most) but cold spells in March or April of -8C to -10C are critical. Plants from continental climate like Poncirus often cannot handle them while less hardy plants with better dormancy can. So depending on the temperature curve of your special climate you may not want to rely on a rootstock like Poncirus that grows too early in spring.

You live in Poland. I suppose you have a more continental climate and so absolute hardiness counts more for you while growth too early in spring is less an issue.

I am not saying this is applicable to all climates, but from what I have seen in the climate where I am, from several Yuzu plants, maybe about 11.5 degrees F ( -11.35 degrees C) might be the limit of what Yuzu can survive, over consecutive years. At 14 degrees F ( -10 degrees C) it will suffer virtually no damage. Below that it will suffer some partial damage. The plant might be able to survive down to 10 or 11 degrees F with serious damage, but will not be able to sustain that year after year. Not in this climate. Maybe somewhere farther South in the U.S. with a longer and warmer growing season it might be able to recover and not slowly decline from that.

My Dunstan citrumelo appears to have more cold tolerance than my Yuzu and can survive better. The leaves will be more likely to fall off, but they can regrow easier. Yuzu does not regrow leaves as well. It's important that the Yuzu keeps its old leaves because it might only grow 30 or 40 percent the number of new leaves the following year as the number of old leaves on the tree. The leaves do appear to be able to recover from partial damage, and can regain some of their green coloration, but if damaged beyond a certain level, they will eventually fall off, often this may not become fully evident until later when things begin warming up.

I would like to point out that these numbers are really not exact, and are more based on my subjective impressions and instincts I have gathered from experiences, with several plants over several years. So I hope that just helps give some anecdotal idea, rather than being taken as exact reliable information.


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