First Frost For Phoenix this Winter

Alliteration - heh heh.  It's going to get cold tomorrow night, and have a hard frost here for the first time this winter.  All of the blossoms on my lemon tree will be wiped out, as there is no way to cover a 15 foot tall thorny tree (oh ya, lemon trees are the only citrus that have Christ-Crown-Of-Thorns-Like spikes on the branches, go figure).  I spotted by the helpful Elgin Nursery yesterday to get some frost cloth and discuss plant hardiness.  They staff there is VERY knowledgeable, friendly, and customer centric.  The lavender we have was purchased there as well.  We discussed strategies for protecting desert plants against a hard frost, here in zone 9 & 10. (Also see links here and here and here [9B] and here [AZ] for more zone information, and here for surprisingly balmy Euro zones, thanks to the Gulf Stream).


I was very focused on "hardy down to ____ temperature" and the fine people at Elgin were nice to say "Yes, But....".  As in, "Yes, they will survive, they will live, down to such and such a temperature, but your plants WILL Burn and be damaged by the cold temperatures."  Elgin was also clear to point out that even though the Glendale or Goodyear or Sky Harbor airports might report one temperature, locally on your property the temperature might be 5 or 10 degrees colder, depending on sun exposure, wind speeds and directions, residual latent heat, etc.  So to be proactive (or perhaps slightly over-reactive) I purchased a box of 32 ounce insulated cups - sadly Costco was the only place to get them, and I had to get 500.  The cups will go on the tops of each cactus arm, as well as groups of aloe blossoms and lantana blossoms.  I may try to cover the honeysuckle as well, but with it now taller than the 6 foot fence, seeking the sun, I doubt the cups will really work.  I have several rolls of blue painter's tape to secure groups of cups together as well.  The 2 frost cloths will cover 2 of my dwarf palms, and many old queen sized & twin sized bed sheets, as well as landscaping tarps to cover other plants.  Of course, all of this will have to be put on in a 40-to-50F rain storm with 20 mph gusts (NOAA link here), so that'll be alot of fun!

My girl friend Anna will be very confused by all the cups and tarps - AND I will have to take the hummingbird feeders down so they don't freeze - but on Saturday everything will come back off, and hopefully most of the blossoms will have survived.

I was saving up links in a notepad file, but to make them more available and useful for others, here's a list of what I dug up on the interwebs yesterday.  If you have only one of these in your yard, you might want to take precautions.  I'm going to go all out, and try everything possible to preserve the growth I've worked so hard to nurture.  It helps me to forget how far underwater my home mortgage is, when I see all the green and blossoms around the yard. 

Sago Palm -15 to 110 (here) and 10F (here) [Many thanks to Dave's Garden, The DBG, and the City of Scottsdale for the helpful links!]

Dwarf (Pigmy) Date Palm Phoenix Roebelenii, hardy to 25F (link here and here) for short periods

Milkweed, down to 25F (here)

Aloe Vera, 21-30F (here)

Hildmann's Cereus (Botanical Name: Cereus hildmannianus) 21-30F (here)
AKA - Mexican Fence Post Cactus

Lantana, 21-30F (here)

Honeysuckle, 10F (here)

Jasmine, 20F (here)

Rosemary, 20F (here)