Frost damage tropical plants, hardiness

phoenixtropicals

Parents, you might want to have your children leave the room during this graffic display of frost damaged plants... ha ha.

Anyways, seems like temperatures at my house got to just barely to 28 F. on New Years eve. They were probably at 29 F. for a while. Unfortunately I wasn't home but I had covered some of my most precious stuff and even included light bulbs on a thermostat that turns on at 40 degrees. I am also lucky enough to have a neighbor that did some emergency covering of some of my other plants. Fortunately, I don't think any of my plants were killed just some of them end up being shorter, which probably means my fruit production this year will be down.

I also learned about the exact temperatures at which certain plants start taking damage, and I also finally have a fairly precise idea of how my yards temps. compare to the SkyHarbor forecast. My yard seems to be consistently 3 degrees cooler than the Sky Harbor forecast which makes it a relatively warm neighborhood.

Another interesting thing I learned is just how good a well covered frost structure can work. Plants that were properly covered and usually get damaged at 32 F. where just peripherally damaged at 28 F., a full 4 degrees cooler which I found very impressive.

See photos and descriptions below. These photos were taken a week after the frost. The reason I didn't take the photos immediately is because many plants, especially mangoes, take a while to show the damage.

phoenixtropicals · Posted: Sat Jan 08, 2011 6:22 pm Post subject: Atemoya Frost Damage

Well, I left my Atemoya completely unprotected. Literature on the web had told my that Atemoyas could take temperatures down to 25 F. so I wasn't too concerned about it. Unfortunately, they are talking about very large trees and they also use the phrase "Large Atemoyas can survive" temperatures down to 25 F. My experience has proven that they start getting seriously hammered at 29 F. If temps. in your neighborhood are going to be under freezing I recommend covering your Atemoya to be safe. A photo of my tree is shown below. Fortunately, the bottom looks good, but it is definitely going to die back some.

phoenixtropicals

No surprise here. Boug's are toast under 32 F. Fortunately, as long the ground doesn't freeze, which it never does, they will come back from their roots. I'm not looking forward to triming those massively thorny branches. Yikes.

phoenixtropicals · Posted: Sat Jan 08, 2011 6:28 pm Post subject: Guavas frost damage

I don't cover my guavas generally because I just have too many of them. As can be seen in the photo the tops got scorched fairly thoroughly. Guavas are tough though so I already know they will come back. The key is to live in a neighborhood where this doesn't happen every year. I've been here 11 years and its happened twice, which isn't too bad.

phoenixtropicals · Posted: Sat Jan 08, 2011 6:35 pm Post subject: Mango frost damage

Fortunately I covered the lower half of my mangoes before going out of town. I also had a 75 watt light bulb in there. As can be seen they took a lot of damage in the unprotected portion. I do see some green in there, but I'm actually not that confident that those parts will make it either. Mangoes seem to pretend they are okay after a freeze and then the damaged sections will suddenly turn black weeks later. Anyways, since about half the tree is in good shape I'm sure they will recover in no time.

phoenixtropicals · Posted: Sat Jan 08, 2011 6:41 pm Post subject: papayas frost damage, hardiness

Well, this was a big surprise for me. These papayas were only covered with a frost cloth tent by my neighbor. No light bulbs or other sources of heat, and they look really good. Papayas usually freeze about 30 F. Also, it seems that this variety Tainung #2 is more frost tolerant than similar papayas I have in my back yard, which are from seeds from the grocery, a variety of Mexican Papayas. The ones in the back yard look worse. Looks like a properly made frost cloth tent, which includes a good patch of ground works really well.

Notice the banana in the back ground. Its leaves are killed but the trunk is in good shape. I don't bother covering it because it is right next to the house and seems to be able to survive anything in that spot.

phoenixtropicals

Even though these papayas are bigger they look worse. However, the leaves were touching the forst cloth because these are too tall to put in a separate support. The trunks look fairly good though, and given the size of these plants I expect them to recover. They were covered with a well placed frost cloth tent, and no external source of heat.

phoenixtropicals

These purple passion fruit were not protected and took some damage on the top. The bottom and the main stems look good though, so I can't complain. This one recovered from being frozen to the ground in 2007.

phoenixtropicals · Posted: Sat Jan 08, 2011 6:53 pm Post subject: plumeria frost damage, hardiness

Only covered with a frost cloth tent, this plumeria only took damage on its tips which were in contact with the cloth. I was really surprised by this considering plumerias freeze right at 32 F.

GermanStar · Joined: 17 Jun 2010 Posts: 117 Location: Fountain Hills, AZ

Ouch. No casualties but quite a few in need of remedial care. The poor papaya doesn't look too good. Sad

phoenixtropicals · Posted: Tue Jan 18, 2011 11:29 am Post subject: Trimmed my mango after freeze

Its been about 3 weeks since the New Year's freeze and I decided to trim my mango tree. I waited a while to make sure I knew what parts were dead. With mangos, by this time after a freeze, everything that is not coming back is either black, wrinkled, or red.

I also wanted to get some sun exposure more to the inside branches so that the tree would branch out from there and have the scaffold branches more shielded from the sun by summer. I figure that the UV level is going to just get worse as summer approaches so I might as well get some sun exposure now.

I know that much of the literature says to wait much longer to prune but in the case of this tree and its level of damage I think its best to put it in a state were it will just put out new growth instead of spending a lot of energy trying to repair damage. I also did notice it is putting out some new growth in the lower, undamaged sections.

Another argument for leaving the plant unpruned is that the burned foliage will protect against another freeze. This is true. However, in my case, trimming back the long damaged branches will allow me to easily cover the entire plant with frost cloth, if needed.

As for my guavas and atemoya, even though the leaves are dead in the tops, the branches are actually in much better shape than the mangoes so they might leaf out. I think I will refrain from pruning them for some time to come.