My method for protecting my citrus is: 1) Wrap trunk of plant to ground in heavy blankets or wrap, and 2) use infrared heat lamp bulbs inserted in flood light fixtures mounted on small squares of plywood board. Set the plywood with lights under the trees - adjust the bulbs so that they are facing toward trunk and up. Use extension cords to plug in.

Remember that it is most important to protect roots and trunk. Leaves can regrow later if burned off by the cold.

These are some of the things that I did last winter...You can build a frame around your tree by using wood posts conduit or PVC(homemade greenhouse). You can hang blankets on this so it doesn't touch much of the leaves. Christmas lights strung around the trunk and lower branches and cover with Frost blankets...Make sure the cover goes all the way to the bottom to retain the heat from the lights.

I am going to try this new product this winter that just came out this month called "Freeze Pruf"...have no idea how well it will work since its brand new? But I will probably spray it and cover it too just to be on the safe side. I'm overly protective,lol. I've nurtured these trees for over two years and would hate to lose them now. I posted two pics below...HTH

http://i168.photobucket.com/albums/u173/mangolover07/PICT0114.jpg

Here is a link that might be useful: {{gwi:563739}}

Great advise from love the yard and puglvr. Thanks puglvr, those pics were interesting. I will give all those suggestions a shot. However, those stakes would only work on my Nam Doc Mai, ( just measured it and its 4' 8 " inches tall ), but the other three are 7 ' to almost 8 '. Don't think it'd be practical with those tree heights.
Question : A former gardener hereabouts told me to let a garden hose trickle water at the base of the mango tree for 4, 5 hours, on the nights when the temp is forecast to drop below 48 deg. What do you guys think ?
I'll be looking at infrared heat lamps and Christmas tree lights also. I agree, after all the TLC of nursing these youngsters along, with the vision of that heavenly harvest in the near future, it would be a tragedy to lose even one tree now. I assume that after a tree is in the ground for 3 + years, and spreads out, growing over say, 10 ft tall, that it is immune to these colds snaps. Right ?

Jofus,

H.depot and Lowe's sells the Conduit(electrical department) and comes in a 10ft length for what its worth. Of course you would have to bury at least 18" or so in the ground(so you're pushing your trees that are 7'-8'.

I'm not familiar enough about the water thing, so I can't comment on it.

As far as trees that are over 10 ft...I don't think any mango(tropical trees) actually get "immune" to freeze. Its just more likely they will "fare" much better and not die because the roots are more established. I've seen some trees in my neighborhood that were over 20 ft that had "severe" frost damage from last years freeze, but they are all alive and have regrown at least half of what they lost. You will still lose leaves and some of the branches, but a much better chance you will not kill the tree?

My Mango and Lychee trees were fine w/out any type of protection to 34°-32° as long as its only a couple of hours or so. The only reason I covered mine when the forecast was 34° was just to be overly cautious...just in case the weatherman was wrong and it dipped a couple of degrees lower. The first year I planted it...I covered them when the temps were forecast to 35° or lower...not to take any chances. Last year I didn't cover them until the forecast was going to be 32° or below. You should have no problems at all at 48°...

Good luck!