Styrofoam cups to the rescue (frost blankets, too)

We've had a very mild winter so far with just a few brief dips below freezing. So much so that I'd been lulled into thinking we were out of the woods. But all that is about to change as an arctic front is headed our way.

The lows forecast by the various weather services vary wildly between 24°F and 28°F. 24°F seems unlikely, but even 28°F isn't good news for our flowering aloes. I'm not worried about the plants themselves—the majority of them are perfectly hardy—but the emerging flowers could be damaged to the point where they stop developing. I'm not covering aloes that are in full bloom, hoping that the flowers are hardy enough to deal with the cold weather.

Taking a cue from what gardeners do in Arizona to protect the growing points of their cacti, I put Styrofoam cups over any emerging aloe flowers and covered the largest aloe with unopened flowers ('Erik the Red') with a frost blanket.

I'll remove the foam cups (and blankets) as soon as this cold snap is over. I promise, I won't become the guy Loree Bohl describes in this hilarious post on her blog, the danger garden.

Aloe humilis × ferox (covered with cups) and Aloe 'Erik the Red' (covered with a frost blanket)

Left to right: Aloe wickensii (covered with cups), Aloe 'Erik the Red' (covered with a frost blanket), and Aloe betsileensis × striata (covered with a cup)

Aloe wickensii covered with cups

Aloe wickensii covered with cups

Aloe hereroensis covered with a cup, Aloe bulbillifera hybrid not covered
 (it flowers multiple times throughout the year anyway)

Aloe 'Yemeni Gold' (an A. sabaea hybrid) covered with cups

Top of this Aloe speciosa × barberae inflorescence covered

I also covered Aloe mawii × globuligemma and Aloe alooides (not pictured) as well as Agave chazaroi, Agave gypsophila × isthmensis, and some San Diego purchases (Aloe divaricata and Dracaena draco):

I'm hoping a) that the lows will be higher than forecast, and b) that my efforts will be enough to prevent the worst damage.

As I mentioned earlier, the forecasts provided by various weather services often vary significantly. Take a look:


Weather Underground (same forecast as Weather Channel above):

Since Davis is a small town, some services (like AccuWeather) use data for Sacramento International Airport, which is 18 miles away in a completely exposed location near the Sacramento River. The most reliable forecasts draw on data from a local source, such as University Airport, a small airport owned by UC Davis. Based on my personal experience, I find that Morecast and the National Weather Service provide the most accurate forecast for our garden.

© Gerhard Bock, 2022. All rights reserved. To receive all new posts by email, please subscribe here.


  1. Here in Citrus Heights. Today is supposed to be the warmest of the frost days and it's white up to the house, Ice on the cars, thick ice in the bird bird bath that's 8 feet from my house. If it's colder tonight and freezes again Friday it's going to be a blood bath for plants and the farmers. My plum and apricots have already bloomed and are leafing out may loose that crop. I have covered stuff will see if it's enough. aloe flowers are toast I think.

    1. I hope your plants made it through OK. Here in Davis, it wasn't quite as bad as I'd thought.

  2. Similar, sub freezing temps in the Seatte are. I re-placed protection (a large, clear plastic salad bowl) on the only tender succulent in my garden. It is fortunate that day temperatures will rise above freezing.
    I do hope the foam cups and blankets will do the trick and we go back to seeing the gorgeous blooms everywhere.

    1. We did have one night with lows around 29 but I don't think there's any damage, at least nothing immediately visible.

  3. Fingers crossed your protective measures helped and perhaps the temps weren't as bad as predicted. BTW the fellow I write about has passed, and his wife offered to let my brother rescue some plants before another piece of their property was sold. Quite the haul. If you saw the recent photo on my Instagram account of the opuntia growing in a can full of hardware (, that belonged to styrofoam guy.

    1. I can't get over that Instagram photo ). An opuntia growing in nothing but rusty metal and nails! Talk about a tough, tough plant!

      My Styrofoam cups did the trick. Some got knocked off during the first night but I put them back the following morning. I removed all the protective gear yesterday and I didn't see any immediate cold damage.


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