The Tropical Fruit Forum

Keraji after 3 years in ground with first flowers

Interesting table, though we all know, that the datas can only show a rough estimate due to complex influences of coldhardiness, as rootstock, ..... From my experience some very cold hardy citrus as Citrumelo x Yuzu, Chimera Prag, Bloomsweet Pomelo, 5* Citrumelo and Morton Citrange are still missing.
Morton ( on Poncirus) and Chimera Prag ( survived in my region -16 °C with fleece protection (Morton on FA 5 with 30% twig damage). The others -13 ° C also as a 1 year old graft of Clem yuz 2-2 on Poncirus.

I know this problem also, citrus are in good shape when remooving protection fleece end of february or march and then deeper nightfrosts and daysun and higher day temperatures then lead to bark cracks. Some of them heal, some lead to infected and dying twigs or
plant. This means to protect against daysun while nigt freezes below -3 or -4 ° C arises and to kerp the plant protected and dormant.

this year it took in pot -8 °C and looked very good begin march, but got stressed by following nightfrosts with daysun in april.
But still no fruits yet, a graft oft it has flowers but they are still closed, so hope to get fruits end of summer - I' m also curious 

I tested grafting already with a few month old seedlings and you have to take care due to the size, but it works well, only the scions also have been seedlings.
But with normal scions not so big you already could graft on one or two year old seedlings.

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.

Final results after this winter

 From 3 now 2 year old N1 tri Voss seedlings finaly this one survived (in March it still seemed to have at least two survivors), they took passiv fleece protected -11 °C


from other 2 year old seedlings one Meyer lemon, star ruby Grapefruit and one Ichangstar 60 died, they took as lowest -8 ° C in their passive fleece protected area.
Survivors two Ichangstar 60, two star rubys and a young graft I x S on flying dragon


My I x S, now 3 winter protected and heating under -7 ° C, looks very bad with a lot of bark cracks from several night frosts with day sun and to early opening of fleece. But I think I will replant this plant or replant it to waste  .




The last problem plant is my Ivia - without protection in winter it showed good shape in march and now it seems to have a trunk disease. I already took a graft, because I don' t know if it will survive ?





Other Plants in ground have done very well, also new ones as Clemyuz22, from planting last summer.

early sunlight is only a problem in combination with nightfrosts. If you don' t have night frost in spring it s no problem. If you have night frosts later sun is better,  when the air is warm and small twigs not frozen anymore. Or as I do, giving shade to the plant until the nightfrezees are over in later spring.

thanks Kumin 

The brick is a quick and easy way for posting the bamboo sticks and perhaps he also brings a little bit of protection to the lower part of the plant.

Cold Hardiness results, low of 9F. -13C:
Dead
Bloomsweet  High grafted and some poncirus growth allowed below.
Juanita
Brown Select
US 119

A lot of damage
Keraji, one larger tree dead.  Another will recover
Curafora
10 Degree 3-3

In better shape, minimal or no damage
10 Degree 2-2
CiClem 10
Ventura Lemondarin
Morton
Swingle
Bishop 852

Very interesting your experience this winter.
Have your trees been protected ?
Also interesting, because most results are according to my experience, only Keraji and Bloomsweet differ.
We also had a low of 9° F, -13° C, but my Keraji and Bloomsweet graft survived without damage. But perhaps you had more consecutive frost day and no frost cloth.
Thanks for sharing your experience. I always find this helpful for relative frost hardiness comparison.

Well My zone 7 experiment failed. Arctic Frost, Orange Frost, and Bumper all succumbed to this years winter. I thought they could male it unprotected but alas they are dead to the roots.

Oh  that s a pity, but I wouldn' t say failed, the first try failed  , there are still a lot of varieties worth for a try in zone 7, though not all have very good fruits. But I think Prag Citsuma, and Carolina lime from Stan Mc Kenzie nurseries should be very frosthardy  and have good fruits.
My Prag Citsuma survived very good 3 winters down to -16 ° C. The only protection was a frost cloth, espeacially for night frosts with day sun in spring.
Have good luck.