What temperature is dangerous? 32 degrees and below.
Yes, I’ve done it, we’ve all done it….. We arrived home from work and heard it’s going to freeze and we don’t want to deal with covering up plants. Or maybe we only care about a couple of key plants. What should you do and what should you expect the next morning?
First of all, you know you are looking at frost damage when you see the following symptoms: Wilted, black leaves, white, bleached out leaves in the new growth, crispy leaves, white pitted spots, brown leaves and finally, in succulents mushy leaves. Now all of these symptoms can also mimic other things, but if you plants were “perfectly fine” and then following a cold temperature warning, the next day you see these symptoms, that’s probably frost damage.
What should you do: If you want to be proactive, the night before, cover up your plants with a plastic sheet. You can use an old bed sheet too in a pinch, but plastic is lighter and will do less damage as you drape over the foliage. You can get a pack of painter’s plastic drop cloths, and just keep them on hand so you can just grab them upon threat of frost in the weather report. I’m going to be honest, I am inherently lazy, so if it’s not easy, I’m likely to blow it off. So just get a pair of scissors and make a tent over you plants cut off the excess and use it for another planting area. You can stake them up, but really, here in California, a simple drop over top and go is going to do the trick.
What should you do if you wake up in the morning and you are now forced to deal with your decision to go to bed the night before: Resist the urge to cut off the ugly foliage, it’s going to provide protection for the foliage underneath the damaged foliage. I know it’s ugly, but just ignore it. You can go back in the spring and trim/thin all that off and you will be shocked at how much your plants can “self heal.”
Remember some of you plants are simply dormant, many plants that are deciduous, look as though frost damage has occurred, but those you can cut back to the ground or just to the new growth line. How do you know if you plant is damaged vs. dormant? Well, first of all look up your plant on the internet or in your “Western Gardener” book. Do cut back the plant as I mentioned to promote fabulous Spring growth if your plant is deciduous. However, if you plant is not deciduous (dormant in winter) as I mentioned, don’t cut it back until the threat of frost if gone in the spring.
New plantings can be really put to the test, but again, just wait. I know it’s ugly, many plants will sprout new growth from their root stock and recover.
Additionally, the nursery said this plant will take frost, what happened? Or, my neighbor’s was fine and mine is looking terrible. Mature plants can withstand lower temperature better than younger plants and some plants need a season to get stronger and then they will be more durable. The other thing that can happen is that the neighbor may have more overhead tree coverage than you do and that can really help protect from the frost. As I said, hang tight, wait until spring and then, evaluate what’s really going on.
Finally, my plants were fine in previous years, why did the frost get to them this year? The degree of frost chilling and injuries depends on the duration of the cold temperature and how fast the temperature dropped and that varies from day to day let alone season to season.