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.