I am about 30 miles from the Gulf in Beaumont, SE Texas. The last two winters have had several especially cold/long duration freeze events. The inground satsumas are totally unaffected, even the very young trees. All the other inground young trees have been defoliated or branches killed to the rootstock even after protecting with a soil bank. Mature grapefruit and round orange trees have been unaffected or just dropped the leaves.

The cold last year was to 19F for a few hours and this year 23F for 20 hours. The top few inches of ground actually froze this year!

From 1989 to 2008, citrus killing freezes were non-existent, I remember only one instance of a late March freeze to 19F for a few hours. If the experience of the last two years continues, I'll never get a grapefruit or round orange big enough to survive.

My latest thinking on planting other than satsuma trees is to plant a satsuma tree and several years on down the road bud the grapefruit/round orange or other less cold hardy varieties to the main trunk high.

My thinking on new plantings is that I have a much better chance at getting a satsuma tree large without winter kill. Then when the tree is large enough to be cold hardy, say 6-8 feet, the less cold hardy variety can be budded high.

Anyone care to comment on my latest strategy? I'm thinking it might be good for any location on the upper Gulf coast.

I'm also thinking about a water mist system but that may not work so good for a long duration freeze.

I fear I'm confusing people:
1) small satsuma trees are cold hardy
2) small orange/grapefruit are not cold hardy
3) large orange/grapefruit are more cold hardy
4) grow satsuma tree until 6-8 feet
5) topwork upper part of tree to orange/grapefruit
6) now I have a large cold hardy orange/grapefruit tree

mrtexas,
I like your idea but why to use satsuma as the host tree?
Perhaps choosing a sprout from rootstock to be new main trunk is something to consider too.
Or why not start P. trifoliata tree just for that (host) purpose.
That needs time, yes, but years will pass anyway.
My 2 cents.

mrtexas,
Seems that what I wrote is not clear enough, my english attack again, sorry.
Consider this photo: P. Trifoliata hosting several grafts



All benefits of using PT as rootstock are preserved that way.
When a nasty cold spell arrive some grafts could be lost
but the host tree (P. Trifoliata) is there to stay and new grafts can be added every year if needed.

I think satsuma mandarins and changsha mandarins are your best bet long term eventhough they may freeze too in the worst years. Orlando Tangelo is also quite cold tolerant for a citrus plant. The others are just not very cold tolerant. I really like the satsuma fruit it is easy to peel and very sweet with not much acid. I am diversifying my edible plantings with pomegranates, figs, bananas etc.

Irragation can be very effective for cold protection if the dew point depression and wind is not too large. There are some freezes though that are very windy with large dew point depression. Also make sure you have back up power,.

I have satsuma mandarins but not changsha. I really want a changsha but cannot find one. I read that the changsha has great tasting fruit but a few too many seeds. The seeds do not bother me though.

There were young grapefruit trees killed here last year, but the mature grapefruit trees seemed unaffected by the cold. There is a huge grapefruit tree near where I live at least 25 feet tall.

None of my citrus plants suffered cold injury this year and hopefully the worst of this winter is over.

What do you think makes the mature oranges and grapefruit trees more hardy? Is it the diameter of the trunk and branches? If so, grafting to satsuma may gain you nothing since the grafted orange and grapefruit branches would still have to grow to large diameter before they become hardy.

It's still worth trying the experiment if it hasn't been done before just to see if the orange or grapefruit scion can be made more hardy on a satsuma rootstock regardless of what the reason might be.

Didnt joe real do this but in a differnt manner and graft the sensitive cultivars to the bottom of the tree to get the canopys cold tolerent varities to shelter the sensitive varieties at the bottm

Here is my method. Take a satsuma with a caliper of 1 - 1 1/2 inches and put a less cold hardy scion on the top. I easily grow out a satsuma to this caliper but have been struggling getting oranges and grapefruit to survive to this size. The scion on top here is sanguinelli blood orange.

Funny that my small citrus froze even banked with dirt in a 3 gallon nursery can. All the small ones that froze were on flying dragon or trifoliate with at least a 1 inch caliper.

No small satsumas froze but grapefruit, ponkan, pong koa and honey mandarin did. Valencia, Nova, and rio grapefruit did not freeze. Funny that my 8 foot yuzu tree lost all it's leaves as yuzu is supposed to be as cold hardy as satsuma! It's all about the dormancy of each individual tree.

My mature multi-graft tree with blood oranges and valencia did not freeze the small top branches at all! Multi-graft is on sour orange rootstock!

The 1989 freeze here was to 10F while this year was to 23F. Duration of freeze was similar.

One thing for sure, this hobby keeps you guessing!

The advantage with seedlings is that even if they freeze they can often grow back from the roots. They are also easier to bank with dirt.

One problem with trifoliate rootstock is that it does not supply enough water to the scion during a severe freeze and this contributes to the dessication of the leaves and bark. Most of the damage to citrus during freezes is caused by dessication of bark and foliage from the very very dry cold air. Most severe freezes are very windy and the wind can accelerate dessication. As the water inside the tissues evaporates from wind and dry air it cools the tissue and ice can form! The ice blocks the flow of water and nutrients. It helps to water a citrus tree thoroughly before a freeze as wet soil can hold more heat than dry soil. The seedlings citrus are probably more cold tolerate because they are growing on their own roots and can supply more water during freezes. Frozen citrus trees suffer symptoms similar to severe drought stress!

I never worry about fig trees freezing because it happens so seldom and even when it does they can grow back from the roots. Grafted citrus cannot recover this way!