After the record heat

Last week’s heat wave in California was one for the record books. All-time highs, many set decades ago, started to fall on Labor Day, September 5. But Tuesday, September 6, turned out to be a real doozie. The Bay Area reached an all-time high of 116°F, recorded in Livermore in the East Bay hills. Downtown San Francisco hit 102°F, miserable for folks not used to hot summers (few homes have air conditioning) but not quite enough to beat the record of 106°F set on September 1, 2017.

Closer to home, Sacramento set a new all-time record of 116°F on September 9. In Davis, 15 miles west of Sacramento, we “only” reached 113°F, three degrees shy of the record of 116°F set almost 100 years ago on July 17, 1925. All in all, we had 10 days above 100°F.

Beyond the physical discomfort caused by the heat, the psychological effect of being cooped up inside, not knowing what kind of damage our plants might be sustaining, was even worse.

Cooped up inside during the height of heat wave, wondering what’s happening to my plants in the 110°+ heat...

The heat wave ended quite spectacularly with a drop of 25°F from Friday, September 9 to Saturday, September 10. The lower temperatures are partially due to smoke from wildfires in Northern California and Oregon obscuring the sun. That’s the reason for the odd orange cast in some of the photos below.

California sunflower (Helianthus californicus) at the UC Davis Arboretum

Stella at the UC Davis Arboretum on Saturday, the first day below 100°F in ten days

While the full effect of the heat damage won’t be known for some time yet, here are some photos of what did well and what didn’t.

Redwoods (Sequoia sempervirens) on the green belt near our house. Planting redwoods in the Central Valley is the height of folly, and these have been declining rapidly as the irrigation for the landscaping has been shut off. The browning you see in the photo above isn’t from this particular heat wave, but it certainly didn’t make things better.

Our summer heat is hard on echeverias. Echeveria agavoides does better than most species (cultivar ‘Ebony’ shown below), but it didn’t escape unscathed. The whole plant is completely bleached, and the lowest leaves are dead.

Echeveria agavoides ‘Ebony’

Most of the top-growth of Euphorbia characias ‘Tasmanian Tiger’ is toast. It’s ugly, but also a good opportunity to tame the beast a bit. It should sprout fresh growth as we move into fall.

Euphorbia characias ‘Tasmanian Tiger’

Aloes are built to handle the lack of water, but high heat is something different. While most of my aloes are fine, one of the rosettes on the Aloe distans below is burned to a crisp. Interestingly, one of my Aloe ‘Hellskloof Bells’, a hybrid between Aloe distans and Aloe pearsonii, has noticeable burns as well.

Aloe distans

Other plants in the same spot next to the sidewalk are thumbing their nose at the heat:

Mangave ‘Black Magic’, Agave zebra, Mangave ‘Sponge Paint’, with the half-burned Aloe distans top right

Next to the tall Corten planter at the top of the photo above, Salvia cedroensis ‘Baja Blanca’, a white-flowering selection of the strikingly beautiful Cedro Island sage, is a goner for the second year in a row. But I like it so much, I’ll grow it as an annual if I must.

Salvia cedroensis ‘Baja Blanca’

Look closely under the crisp salvia leaves. A pup from Agave zebra a good five feet away! When I dug it up, I actually found a second one.

Aloe zebra

Here’s the main plant, still a juvenile specimen. Aloe zebra is one my favorite species. I don’t why it isn’t more common in cultivation.

Agave zebra

Not too far away, another crispy perennial, Sideritis cypria. Actually, I’m holding out hope that it might come back from the roots, so I’ll leave it be for now.

Mangave ‘Pineapple Punch’ and Mangave ‘Night Owl’ (top), Sideritis cypria (bottom)

I’ve never seen any Hechtia argentea this bleached—it’s like the trichomes on the leaf surfaces have evaporated. It’ll be interesting to see if it will bounced back.

Mangave ‘Red Wing’ (top) and Hechtia argentea (bottom)

A recently planted Agave victoria-reginae has wrinkled skin (and brown spots):

Agave victoriae-reginae

Some agaves, mangaves, and aloes have curled up into awkward tangles to protect their vital core:

Agave ‘Ripple Effect’

Mangave ‘Mission to Mars’

Mangave ‘Spotty Dotty’. The leaves are a tangled mess, but the flowers look completely unaffected.

Aloe capitata var. quartziticola

Aloe karasbergensis

Other plants are completely unfazed, looking as good now as they did before the heat wave:

Epilobium canum ‘Carman’s Grey’, Yucca gloriosa ‘Bright Star’

Leucadendron ‘Ebony’ is even coning!

Leucadendron ‘Ebony’

Acacia cognata ‘Cousin Itt’ seems to look even more lush that before!

Acacia cognata ‘Cousin Itt’ (front), Aloe ‘Tangerine’ and Mangave ‘Queen for a Day’ (top left), Agave potatorum (top right)

And even my Sarracenia experiment isn’t a total failure. This is the first time I’ve been trying to grow these carnivorous beauties, and while they haven’t looked pristine since the spring, they haven’t croaked either. They do need as much direct sunlight as possible so it’s a delicate balancing act.

Multiple Sarracenia in an oh-so-trendy plastic container

But the biggest event happening right now is this:

Agave bovicornuta

My Agave bovicornuta is sending up a flower stalk. After a slow start, its progress has begun to speed up. I’ll have an update in a separate post.

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


  1. What a sad post. Its heart breaking to see so many damaged plants in your collection. I can't even imagine 10 days over 100°. I do hope cooler temps and perhaps a bit of rain will revive some. Yucca gloriosa ‘Bright Star’ is indeed glorious and a truly a bright star in your garden. The green lushness of ‘Cousin Itt’ must also be a delight to look it at the moment.
    I too experimented for the first time with Sarracenia on my patio. I'll be thrilled if they return next spring.
    Little spiders made it all the way up to the 5th floor and attempted to capture in their web whatever tiny bugs were attracted to the Sarracenia. I chuckled at their ingenuity and entrepreneurial genius.

    1. I love your observation about tiny spiders trying to catch the bugs attracted to your Sarracenia! I've read that they literally trap dozens of tiny insects each day!

  2. I'm surprised at how much came through those temps unscathed! And so exciting about your cowhorn agave -- I wonder if it will have bulbils along the spike...

    1. Me too! All in all, I'm pretty happy!

      No bulbils from Agave bovicornuta, but hopefully seeds. A friend is sending me some pollen from Agave gracilipes so I can try to hybridize the two.

  3. Ouch! I'm stubbornly refusing to survey my garden until our current 15-day outdoor watering ban is over next week, but we didn't fare nearly as badly as you did with respect to the heat - we topped out at 106F but, unlike many of the prior heatwaves when we've gone that high and higher, we didn't get stuck there. Meanwhile the San Fernando Valley peaked at 112F and remained above 100F longer than we did. One Coleonema I can't help seeing went completely brown but it was stressed (by low water) well before the heat hit. Yay for Acacia 'Cousin Itt" and Yucca 'Bright Star'! The variable effects on Mangaves is interesting but perhaps to be expected given their very variable parentage.

    1. You're wise. Don't look until the ban is over. You might be surprised. If not, heck, planting season is just around the corner, ha ha.

  4. So sorry to hear, Gerhard, about your plants! I have some of them but mine are not in sun at all since Phoenix is that hot most of July and August. I have Aloe karasbergensis but in the shade and it does very well! Hope many of them will come back soon from their roots!

    1. I think I'll move that Aloe karasbergensis. It isn't happy in that much sun. I have another one that only gets some morning sun, and it's plump and blue!

  5. Oh, yikes, capitata var quartzicola. Ow. Ow. That hurts. The center looks okay, though. karasbergensis, too. That one is so touchy here. I'm going to try mine in morning sun/afternoon shade. All day seems too much for it, but it didn't like all shade here, either.

    Your poor plants. Much more damage than here. We had 11 over about 93, but only about 4 that hit more than 100. Much hotter for you. Sorry to see you had some casualties.

    Yes, fall planting just ahead!

    1. I don't think the aloes and agaves that have twisted themselves into pretzels will die. With cooler temperatures and more moisture, they should return to normal eventually.

  6. Surprised the agaves suffered as much as they did. Despite it's yellowed sunburn the Hechtia is quite attract with it's bright yellow leaves. Complaining here about temperatures in the 90's. Can't imagine 20 degrees more. Thankfully it's cooled.

    1. This latest heat wave took me by surprise. Silly me, I'd thought we were out of the woods, crusing toward cooler fall weather...

  7. Odd when we are happy for smoke in the sky isn't it? It definitely kept our temperatures down over what was supposed to be a very hot weekend (last). Congrats on the successful sarracenia grow. You definitely need to check out my blog on Monday where I'll be sharing photos from a local sarracenia grower. I can't wait to see more about your Agave bovicornuta!

    1. Yeah, Sarracenia photos from a pro! That'll be nice.

      My Agave bovicornuta is making slow but steady progress. Still, I don't quite know if it'll actually bloom this year or, like A. parrasana and others, take a break for the winter and then continue in the spring.

    2. Oh they're not photos from a pro, they're my photos of a growers plants.


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