The Elusive Michigan Citrus: A Lifetime Experiment

[Mulberry0126]

My Poncirus+ is looking very yellow, is there anything I can do to bring some green back to it?

I also noticed that one of my Dunstan Citrumelo seedlings, and one of the two lemon seedlings I have (of the same fruit), have thick, deep green, leaves, with serrated edges. Does this mean they might be tetraploid?

It looks like that tree could benefit from a shot of nitrogen - a liquid fertilizer will act quickly. As for those seedlings, see if you can snap a picture. Some members on this forum are very good at identifying tetraploid plants. Based on your description though, it does sound like they are tetraploids! This could be valuable for you if they gain any significant cold hardiness that would allow them to survive in your zone.

[bussone]

I've heard of it surviving 5b, but that was down by Chelsea, which is 6a now. Your hope with hybrids probably lies along the Lake Michigan coast line and only a few miles inland from there, which is 6b. I know poncirus does okay there, because the one I gave my mother is still alive.

Visited those trees this week. They are alive, although still really bitty in size. They survived a prolonged hard freeze without cover this winter, and they are planted in a shady area -- the combination of the two means they are all still runts, especially compared to their sibling seedling in the Philadelphia area. But they are also all alive -- even the one that got nibbled by a rabbit.

[Lobotomy]

Visited those trees this week. They are alive, although still really bitty in size. They survived a prolonged hard freeze without cover this winter, and they are planted in a shady area -- the combination of the two means they are all still runts, especially compared to their sibling seedling in the Philadelphia area. But they are also all alive -- even the one that got nibbled by a rabbit.

That's a heartening result. How old are those plants now?

It looks like that tree could benefit from a shot of nitrogen - a liquid fertilizer will act quickly. As for those seedlings, see if you can snap a picture. Some members on this forum are very good at identifying tetraploid plants. Based on your description though, it does sound like they are tetraploids! This could be valuable for you if they gain any significant cold hardiness that would allow them to survive in your zone.

That definitely did it. The old growth is very slow to green back up, but the Poncirus+ very much enjoyed the nitrogen I've applied (three rounds, once bi-weekly), and put out some very healthy looking new growth. I may soon have enough budwood to make an insurance graft, as I do not want to have to hunt one of these specimens down again.

As for tetraploidy, on second look, I don't think that's what was going on.

So far, all of the plants are in very good order, except for my Pink Lemon, which is slightly pale at the moment. I've been adding a slight random pattern (1-2x/week, give or take up to four days) to my watering to simulate drought, and they're all getting through that with ease. As they are in the greenhouse, I have been their only source of water. All of them got a round or two of nitrogen, and seem to be very happy. All of my Dunstan seedlings have exploded in growth in one direction or another. The FD x Moro Blood Orange fruits are still growing at a reasonable pace, although, I don't know how long the fruit takes to mature. Hopefully it's soon, because this is the first kinda brisk day we've had since the thaw.

[bussone]

Visited those trees this week. They are alive, although still really bitty in size. They survived a prolonged hard freeze without cover this winter, and they are planted in a shady area -- the combination of the two means they are all still runts, especially compared to their sibling seedling in the Philadelphia area. But they are also all alive -- even the one that got nibbled by a rabbit.

That's a heartening result. How old are those plants now?

This is their third year, I think.

I've noticed my poncirus here tends to put on growth flushes when its hot. I do wonder if poncirus needs a fair amount of summer heat, even though it's cold tolerant.

My hardy figs act like that, too.

[SoCal2warm]

I've noticed my poncirus here tends to put on growth flushes when its hot. I do wonder if poncirus needs a fair amount of summer heat, even though it's cold tolerant.

My hardy figs act like that, too.

I was thinking about commenting in this thread, but waited until now.
I was reluctant to post anything, afraid it would be off topic, since my observations come from the growing zone in the Pacific Northwest.

In the Pacific Northwest, which gets much less cold than Michigan, but has a growing season which is very slow to heat up, I've noticed that many poncirus hybrids have no trouble surviving the winters here, but just have trouble putting on much growth the rest of the year. In fact I'd almost say that Yuzu almost seems to grow "better" here than poncirus hybrids, even though Yuzu has a fair chance of suffering severe die-back (or even slow decline over 2 years and eventual death) if not planted in an optimal spot.

I have a US-852, a tiny plant, that is surviving in the ground here, but almost doesn't seem to be putting on any growth. After more than 3 years. Not just one plant but several seedlings in containers outside. I suspect it may be due to the lack of a long enough growing season with enough heat. Yuzu may be much more vulnerable to the winter cold here, but puts on a much faster growth rate. Same thing with Changsha mandarin. Though I think for some reason pomelo, grapefruit and orange genes seem to contribute to faster growth rate in poncirus hybrids, despite being more "heat-loving".