Re: How to winterize my lemon / lime trees
You are probably very similar to here. Normal winters are a few nights in the upper 20s, maybe 2 out of 10 we do not get a killing frost, but once every 10 to 20 years we get a freeze in the low 20s to upper teens. Last yr we got into the low 20s and I covered my inground trees with sheets, tarps, burlap, landscape fabric--anything I could get. I placed bags of composted cow manure around the base (similar to banking). I put as many 5 gal buckets of water as I could get under the trees (and under the cover--water gives off heat as it freezes). On my Lisbon lemon, I added 2 strings of Christmas lights. None of my trees had anything more than minor damage--like where a limb was touching a tarp.
I have lemons, mandarins, oranges, tangelos, satsumas, kumquats inground. Key limes were brought inside.
One major factor is whether the trees have had time to harden off to the cold--exposure to 40s and 50s for a month or so--without an exposure to 80s for a while. If trees have not had time to harden, a hard frost (mid 30s-actual air temp) can do serious damage.
One other technique that I did not use is water spray. In case of hard freezes, a spray nozzle that delivers 8-10 gal/hr into the scaffold limbs will save the heart of the tree. The outer limbs will be lost, but the tree will be back in production in a yr. A seminar by Auburn Univ suggest this can save a tree in freezes as low as 12-15 degrees.
Banking is an old technique for saving the trunk in case of hard freezes-- the trunk of the tree is covered with dirt at least a foot or so above the graft. Without the scaffold limbs it can take a couple years to return to full production, but it will save the tree.