Flavor in cooler climates

[gordonh1]

Regarding growing citrus in northern climates, especially in the Pacific Northwest, apart from the issue of hardiness is the issue of not enough heat to properly ripen fruits. I'd like to hear thoughts on this. For example, it is said that Dunstan, a Poncirus hybrid, could be hardy enough to survive zone 8, maybe with some protection from extremes of cold, but also it's said that its flavor is acceptable for fresh eating, but with some caveats, especially that it is most palatable when fully ripe. So I've been wondering how the taste of Dunstan might differ when grown in a cool climate like the PNW, from the same variety grown in a climate with hot summers in the same zone, like North Carolina. Would the palatability issue be more difficult to overcome in the cool climate where the fruits might not develop as much good flavor to overcome to less desirable flavors? 

I gave the example of Dunstan, since it has been reported to possibly be a good candidate for growing in my area. I also have a Dunstan that I just got from Woodlander's Nursery. However, the question applies to all the hardy citrus. What additional considerations regarding flavor and ripening heat requirements do growers in climates with cooler summers have to consider when growing the hardiest citrus, especially the Poncirus hybrids?

[caladri]

Consider also fruit holding and interventions you're willing to engage in to increase fruit holding, so that you can ripen across multiple seasons. That's my preferred approach to handling our Pacific Northwest summers, and there are a few folks doing the same with some success. (I think Bob Duncan in North Saanich got a Trovita sweet orange to hold two or three crops on it at a time and to ripen fully, but he's willing to be a lot more aggressive with winter interventions than I am.)

[gordonh1]

I had heard about Bob Duncan's success with Trovita oranges allowed to ripen over two seasons. I just saw this on his YT channel:
https://www.youtube.com/watch?v=pZ_UJe9hbqM

It would be important to keep the fruits from being damaged over the winter. Saanich, where Bob lives, is surrounded by water and has a locally anomalous mild climate. I don't know if I can get away with that as easily where I am, at slightly higher elevation, and away from the water. Or it just might require a protective blanket like Reemay or a frost blanket with a string of Christmas lights, which he recommends.

What do you think about the choice of cultivar for this type of culture? Bob shows success with several citrus types that aren't known for their extreme hardiness, but for me I'm looking more at hardier types that would be more likely to ripen before the arrival of frosts, at least close to it.

[caladri]

You can find fruit holding data for a lot of the varieties that NARO provide data on in the Japanese context, but it's rather more scattered with most other countries. Some things hold their fruit quite well and are even normally ripened across multiple growing seasons in some commercial settings. What's less well quantified, unless it's captured in some of the more complex biological models, is what the time-temperature thresholds are for fruit drop in winter in different cultivars. Some things will hold through sustained frost, and then happily ripen later, while others will hold only through a brief drop; some will hold fruit but not ripen further, others will drop fruit at the first sign of chill. I'm being vague because I haven't seen that quantified well, and the influence of things like sun exposure, wind, soil moisture, etc., are probably nontrivial. It's worth experimenting with. I'd say play with a bunch of short-season citrus that appeal to you, get mature trees in ground, and let your unripe fruit hang and see what happens. You might even do a bit of data logging and could probably get a publication out of it

[drymifolia]

I don't have an answer to the question, but also interested in knowing the answer. I have a rooted cutting of Dunstan that just started pushing new growth, and do plan to plant it out at some point. I also have Prague citsuma grafts, some hopefully rooting cuttings of sudachi and ichandrin, and one graft of VI 396, which is another "citsuma" chimera from the CCPP collection, albeit with allegedly inferior fruit. These are all fresh grafts/clones this spring, so nowhere near fruiting size.

[caladri]

I don't know if CCPP ever confirmed that VI 396 is indeed a hand-in-glove chimera, and whether it is the same as the Prague Citsuma that others possess (fruit quality suggests not), however they received a Prague Citsuma sample for CCPP processing this February. It would be interesting to see if we could get analyses done of both VI 396 and the new accession.

[gordonh1]

I did find some basic information, such as this article:
https://irrec.ifas.ufl.edu/flcitrus/pdfs/short_course_and_workshop/citrus_flowering_97/Goldschmidt-Effect_of_Climate_on_Fruit_Development.pdf

It is not detailed, but it says that fruit ripens more slowly, is smaller, and has a lower sugar/acid ratio in a cooler climate than in a hot climate.

It also has some information about the color change of fruits, which is influenced by temperature as well. Oranges grown in tropical areas don't develop the deep orange color, because it is cool temperatures that trigger the color changes.

In the absence of any data for much cooler/colder climates, I'd guess that fruit ripening time will be even longer, fruit will be smaller, and more sour, less sweet, but at least the color will be good and not still green.

It will be interesting to see this process as I grow my trees and see the development of the fruit. I particularly like grapefruit, which unfortunately is also slow to ripen. I'm drying Dunstan citrumelo, just ordered a Swingle citrumelo, and will also try Bloomsweet. I hope at least one of these will produce something I can eat.  At least if sugar is low, you can still add sugar at the table, but it must at least have some degree of ripening before there's a significant risk of frost damage.

[caladri]

Indeed, depending on where you are in Western Washington, I'd expect like 3 seasons to ripen most varieties of grapefruit. Could be a fun/tedious experiment! If you're willing to engage in heroic measures to overwinter fruit (I'm not), it could be totally doable on an ongoing basis, depending on the fruit holding properties. There's always taking the approach of going hard on breeding. Say, an early ripening grapefruit with something you like the fruit holding behaviour of. Become one of us who are growing ridiculous numbers of citrus from seed

[gordonh1]

That will probably be me in a few years. I already start a lot of more complex seeds, such as trees and shrubs, medicinal herbs, perennials in addition to the much easier vegetables. And I did start growing Citrus from seeds. So far, I've started Flying Dragon, Yuzu, Dunstan, Ichang lemon, and Kiku daidai. That last was a bonus seed packet someone sent me - I had to look that one up. It's a fairly hardy sour, bitter orange-like citrus, not considered edible, but grown in Japan to a small extent. And it is known to hold fruit for several years.

I will also soon have some citrandarin (852) seeds to try.

I do have a greenhouse under construction that should be done before the coming winter, so I'm hoping to have an environment to overwinter some plants.  But that's not the ultimate goal. I would want to grow as much as possible outside, as long as the protection requirements are not too overwhelming.  I'm sure I can wrap some trees in Reemay fabric and string up some Christmas lights.  Lots of options, and still finding out what works for my situation. 

Breeding some Citrus and trialing them outside, yes absolutely. I do find myself thinking about which ones I could use as parents and how to scale up my operation to accommodate trialing as many seedlings as possible. I don't think I could ever grow 20,000 as we've read about in Kumin's thread, but then I'm in zone 8, theoretically, with once-per-decade drops under 10 F that technically are zone 7b winters. That's in Duvall, Washington, east of Seattle up at 550 foot elevation.  And with a good choice of parents (with zygotic  seeds?), and not quite as demanding a cold tolerance, maybe a mass selection experiment is more feasible in a field not much bigger than an average vegetable garden.  I'm thinking about it, but I have a lot to learn in the meantime.

[Lyn38]

Regarding growing citrus in northern climates, especially in the Pacific Northwest, apart from the issue of hardiness is the issue of not enough heat to properly ripen fruits. I'd like to hear thoughts on this. For example, it is said that Dunstan, a Poncirus hybrid, could be hardy enough to survive zone 8, maybe with some protection from extremes of cold, but also it's said that its flavor is acceptable for fresh eating, but with some caveats, especially that it is most palatable when fully ripe. So I've been wondering how the taste of Dunstan might differ when grown in a cool climate like the PNW, from the same variety grown in a climate with hot summers in the same zone, like North Carolina. Would the palatability issue be more difficult to overcome in the cool climate where the fruits might not develop as much good flavor to overcome to less desirable flavors? 

I gave the example of Dunstan, since it has been reported to possibly be a good candidate for growing in my area. I also have a Dunstan that I just got from Woodlander's Nursery. However, the question applies to all the hardy citrus. What additional considerations regarding flavor and ripening heat requirements do growers in climates with cooler summers have to consider when growing the hardiest citrus, especially the Poncirus hybrids?

I don't know how ambitious you are, but before there were greenhouses there were heat amplifying and retaining "warming walls" built of earth or better yet cement on the north side of fruit. Sometimes even on all sides with the trees planted to the northern part of each "room". Then people went a step further and espaliered the fruit trees onto the wall or a few inches away from it. You could also use paving stones on the ground.

I also don't know about Dunstan, but we just lost our 30+ foot zone 8 neighborhood grapefruit tree, not because of the cold, but because we had a lot of wet snow which caused it to fall over. It was planted next to a house and survived some pretty cold winters. I think it may have been a Duncan. It tasted pretty good. We do have hot summers though, far northern Ca.

& although Meyer's lemon isn't true to seed it might be worth planting some seed and seeing what you get. I have one that I cloned off an abandoned tree in a cold spot in zone 8 that I think might be a Meyer's seedling. It's more cold hardy than Meyer's is supposed to be and doesn't clone easily like a Meyer's.

[gordonh1]

I have a southwestern slope with full sun exposure, and we have some concrete walls there, so the site is ideal for heat-retaining qualities.  Our Desert King fig does well and produces a crop every August.

I'm just learning experimenting with citrus, but so far I have a Flying Dragon in ground and haven't dared to plant anything else, although I have two Yuzu, so one may go in the ground and one may be destined for greenhouse living. But one thing I have read on the forum is that young seedlings are more vulnerable than mature plants, so a logical strategy would be to grow them as container plants in the greenhouse and then plant outside when they're a few years old.

I love hearing the stories about trees like the grapefruit surviving just fine for many years. Too bad it succumbed to excessive snowfall. We have the potential for that calamity as well, as one winter storm brought three feet of snow and caused much tree damage. That was before we had all the orchard trees.  I have noticed that trees on full-size rootstock do much better at withstanding the weight of snow. The ones on dwarf rootstock seem to need to be staked, and those that weren't have often leaned over or in some cases, branches have broken.  It's not a good trend when the trees get a lean that only seems to increase with more heavy snowfall events.

[Lyn38]

One thing I've learned here is that cuttings and more mature container plants don't have a chance to grow a deep taproot and have a tendency to fall. The container plants roots  wrap around the base of the container and won't grow deeply after that. I suspect the grapefruit was one of the above. If you have a deep enough container so the tap root doesn't stall then it's ok.

But.. you're in 8a "average (lowest) temperature is 10° to 15°F" whereas I'm in a warmer 8b.. I think you might need some kind of backup heat source for most. Even just Christmas lights. Otherwise you could have a really nice tree for 2 or 8 years and then wham with a cold spell.

I think the flavor of fruit will depend more on the temps as the fruit is ripening. My summers are hot. My Washingtonia navel put out dry flavorless fruit this past year. Usually it's just a little more tart than grocery stores but still good. It was also unusually cold this fall and winter as the fruit was near ripening. I think the fruit might have froze. Someone else wondered if maybe its rootstock went dormant and stalled the whole tree. Rootstock is probably flying dragon trifoliate.

[Lyn38]

I think trialing seeds is a good idea too.

[gordonh1]

Flavor development is also variety-dependent. I have read that Trovita orange has the ability to develop sweetness without the heat that other varieties need. This genetic ability to sweeten would be a good trait to have in cold-hardy citrus, so what other varieties have this ability? And would Trovita be a good orange to include in breeding programs?

[tedburn]

I think flavour is relativ, everyone interprets good flavour different, but with my flavour in my conditions south Germany, zone 7, my citrus in summer on a south to south east veranda and winter in greenhouse down to 1°C I can report from my experience that I have since some years very delicious satsumas, pomelo valentine and cocktailpomelo, Kumquat fukushu and meiwa and lemon.
I also like my Navel oranges which are more sour than sweet but delicious.