Article: Frost Protection (PDF) Lucy Bradley, Urban Horticulture, Univ. of Ariz.
Ken Ames' Insights on Frost Damage
Ken Ames was asked to stand up and talk a little bit about the frost damage that had
occurred to him and several others around the county.
Ken stated that he had temps of 24 degrees for 3 nights. It was a sustained freeze for the entire night. He stated that temps can go down into the 20s if it is only for
a short period of time (~ 30 minutes or so) and your Plumeria should be fine. It is the extended period of cold that will cause the damage. Of the 67 trees that he had planted in the ground, he had to cut back 62 of them to the trunks. 100% of what he had in outdoor pots did not make it.
What happens is that the latex freezes. Once you decide to cut the plant you need to make sure you cut to white wood. You will also want to seal the end with lime paste or Dap. The lime paste has a natural antifungal element in it.
Ken suggested that one thing that can be done if you know there is going to be a freeze is to hose off your plants, because the dust will attract moisture to the plant and cause it to freeze. Also, if you have an eve or patio cover, move your plants under them. Even that little bit of protection will help.
Several suggestions were made about some other things that might be done. Carl Herzog said that styrofoam cups can be placed over the tips. Someone else suggested using white cotton socks over the tips. Christmas tree lights can be wrapped around the plant for additional heat as well. Nursery supply houses carry a freeze cloth that can be used to cover your plants. It was suggested that you do not use plastic to cover your plants because it will absorb the cold and help freeze the plant. Damage from freeze will not travel down the plant, rot damage will. Freeze can come up from the bottom of the plant too. If you have to cut back to the trunk, don’t worry. As long as the roots aren’t dead, the plant will come back.
From the March 2006 SCPS newsletter; notes taken by Shawn Struever.
By Shawn Struever
I recently asked some of our members what I should tell friends of mine who were experiencing frost damage to one of their Plumerias. Roland requested that I send him all the responses I got, so that he could incorporate them into the February Journal. Here are those responses:
1) Cut now! Take a cut to where you believe the black and gunk end. Then take one more cut to be sure. It is imperative that after each cut you wipe your cutting blade clean with rubbing alcohol. Then seal the end with a pruning seal.
2) Hard question to answer. I guess it is a personal choice. I have been cutting the mushy oozing tips. I don't see why more cold would damage them anymore than if they remained uncut. If new growth popped out, (which seems unlikely) it would get damaged but cut tips? I don't know. Maybe, maybe not. If the cut tips do suffer more cold damage, I will just cut again. I intend to recut in spring, anyway, to get best shaping of damaged trees. Ken recommends that the cuts be sealed with lime paste or caulking or something. I used lime paste. I have more plants to look and decide to cut or not to cut. If the tips are firm but dead looking I might leave them on and see what happens. Some people are spraying the damaged tips with fungicide which I suppose is to dry them out and keep fungus from taking hold, possibly? I don't do that, yet. If I did, I would use dusting sulphur not spray.
3) Cut off the bad part NOW, and again if there is damage later - I THINK that the rot can spread, no use taking chances!
4) Trim down to the frost damage and cover with lime paste. The key is not to let bacteria in from the damaged areas. Cut to clean, visible dermis. A little "milking" of the latex is also an indication that you have safely attained the proper margins for protection.
5) Cut them back to normal tissue. I would not wait, and get to the cutting part right now and hope-- no more frost.
6) My recommendation would be to cut them now to healthy tissue; otherwise the disease would just continue to travel down the healthy tissue. Don't forget the lime paste.
7) We visited Jim Clark on Sunday to get his opinion on the same topic. He thought it best to wait before cutting. He also suggested watching the plant closely and if the black continues to move quickly then he would cut and seal with whatever strong seal they normally use. Perhaps the "DAP" sealer suggested by Bud at one meeting last year.
8) I would cut off the ozzie stuff with a very sharp knife that has been cleaned with alcohol and clean the knife every time I use it. Protect the cut end with a sealant. Now protect the plant from the weather. Make sure the plant is hydrated, when the plant isn't the cold damage is worse on a weaker plant. Next move it closer to the house or a wall where the sunlight has warmed it all day (radiating heat). If the plant can't be moved cover with frost cloth and if you use plastic you must use a heat source (plastic insulates). Christmas tree lights are doing well for me, but if the temperatures are really low you should use lights that put out more heat. Please use extension cords for outdoor use. Try to set the bulbs just below the tips. Good luck and keep me posted.
(Editor's Note: First of all I would like to thank Shawn for putting together the replies she received in her quest to help friends who suffered from the unusual cold we had here in Southern California.
I would like to add one foot note to this list. Tom Piergrossi, one of our members and the host of "Down to Earth" on the San Diego County Cable Station (Channel 66 in North County) included on his program for the month of February "What to do and not do, after a frost".
I was very pleased that Tom included Plumeria during the program. The basis of Tom's program was first and foremost do nothing. If some of the dead leaves on plants are unsightly you can cut them but they may also act as a protector for the new tip growth on most plants. When he finally showed a Plumeria with a soft black tip, he stated that you must cut it immediately. Cut the branch back as far as needed to get to clear white clear wood. Tom also stated that it was not necessary to seal the cut, the Plumeria would seal itself. (Personally, I would seal with some anti fungal as a precaution.)
We will obviously have a great deal of discussion on this topic at the February Meeting. I have asked Ken Ames to share some of his thoughts on the subject. As some of you may or may not know Ken suffered a great deal of damage from this cold snap. I am sure he has a lot to share including what he is going to do now to save as many plants as he can and also what he may do to protect plants from another cold snap.)
From the February 2006 SCPS newsletter.