Frosthardiness experience with citrusvarieties in zone 7, down to 3,2 F

[tedburn]

After my citrus  survived very good freezy February 2023,
March with nightfreezes and daysun stressed some
of my citrus more than I thought.


New Clemyuz22 graft on Poncirus and Citrumelo x Yuzu also now look very good


Ichangensis x sinensis looked very good, when I removed winter protection fleece end of February, now after a few weeks with nightfreezes and daysun it looks stressed, sun protection would have been necessary.


New grafts of Nippon Orangequat left and Keraji right on Sanford Curafora, looked also very healthy after removing of protection fleece. Now Nippon graft seems to be much damaged, Keraji only light damage.


Satsuma Collot, which is planted near Ichangensis  x Sinensis shows no damage of late night freezes.

[tedburn]

Interesting difference in hardiness between Ichangensis x Sinensis ( I x S), due to rootstock and sun exposition


Small I x S  graft on PT, which saw  - 8 ° C under passive protection and from March on without protection nightfreezes with daysun. Absolut no damage  .
The plants beside are star ruby seedlings, more frost hardy tjan I thought.


I x S, on unknown rootstock, with passive protection until March and heater when temps. fallen under -7 ° C.
In March nearly no damage, after no protection in March with night freezes and daysun got a lot of damage at small twigs with deadly bark cracks.
Difference to small I x S, no Poncirus rootstock and morning sun about 1 h earlier and longer sun in the afternoon.

[CarolinaZone]

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.

[kumin]

 Bishop Citrandarin, possible progeny of 852 Citrandarin. This tree is grafted onto Poncirus and has only been field planted since last Summer. The tree was exposed to prolonged to 2°F temperatures accompanied by high winds. The tree exhibits obvious damage, but appears to be recovering. The original tree was planted and fruited by Hardy Vermont.

[tedburn]

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.

[tedburn]

 Bishop Citrandarin, possible progeny of 852 Citrandarin. This tree is grafted onto Poncirus and has only been field planted since last Summer. The tree was exposed to prolonged to 2°F temperatures accompanied by high winds. The tree exhibits obvious damage, but appears to be recovering. The original tree was planted and fruited by Hardy Vermont.

That sounds very hardy, even for the not so big plant. Did you already taste the fruits ?

[kumin]

I received fruits and tasted them. My grafted plants haven't fruited yet, but should within a year or two.

Bishop has indeed survived.

[Walt]

I thought my Bishop citandarin was dead.  But yesterday I saw two tiny green leaves.  Impressive here in central Kansas.  Zone 6.  Trunk and branches don't look good.  It might still die.  But still impressive.

[bussone]

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.

Has anyone ever clarified what Carolina Lime is? Other than it appears to have poncirus ancestry.

[Pandan]

Has anyone ever clarified what Carolina Lime is? Other than it appears to have poncirus ancestry.

Very good liime substitue from what ive gathered tho iive yet to try it

https://www.youtube.com/shorts/dVf37w9fk1A

[mikkel]

Carolina Lime is an unknown seedling that came to Stan Mckenzie from Bernhard Voss. It was probably the original seedling and Stan now has the mother plant. But the parentage remains a mystery.

[hardyvermont]

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

[tedburn]

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.

[hardyvermont]

None of the trees described here were protected except US 119.   

[tedburn]

I received fruits and tasted them. My grafted plants haven't fruited yet, but should within a year or two.


Bishop has indeed survived.

Is anything known about the parents of this cross anf if it is also spread in Europe - would be worthfull here too 

[kumin]

It's believed to be a seedling of US 852, perhaps by self pollination. 852 is a hybrid of Changsha mandarin and Poncirus trifoliata. Changsha is among the hardiest edible Citrus types.

This is a slightly more recent photo showing newly emerged buds.

[tedburn]

thanks Kumin 

[tedburn]

This year some of my inground citrus shows small progresses but at least for me a great pleasure  .


after 3 years in ground Sanford Curafora shows first flower buds



last years graft of Nippon Orangequat on Sanford Curafora   survived just over graft unit 



Also one year old Keraji graft on Sanford Curafora with nearly no problems



Citsuma Prag also starts to build flower buds the second year, though the plant is still small and slow growing after 3 years in ground 



Citrumelo x Yuzu for the first time with flower buds, seems to be very cold hardy up to now

[tedburn]

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.

[mikkel]

are these IchangStar60, seedlings or grafted ones?

[tedburn]

These are seedlings. The grafted ones are still in pot.

[mikkel]

Did all the seedlings survive or did some freeze to death?

[Perplexed]

I had some Ichangstar60 seedlings, most of them died but about 3 or 4 are coming back from the roots after 4 days below freezing and a low of 9F.

[tedburn]

Did all the seedlings survive or did some freeze to death?

From 3 Ichangstar 60 seedlings did 2 survive. But lowest temperature was only -8. But I think more severe have been several late frosts with daysun

[tedburn]

I had some Ichangstar60 seedlings, most of them died but about 3 or 4 are coming back from the roots after 4 days below freezing and a low of 9F.

That sounds good, frost hardiness also should get a little better with age and size.
I have a 2 year grafted ichangstar 60 on PT which gets in ground the bext days. Im very excited how hardy it will be compared to my other in ground citrus hybrids.