Heat sufferers and thrivers (June 2021)

Last week's heat wave was early and intense, setting new temperatures records in Sacramento and many other places up and down the Central Valley (110°F/43°C on Friday in Sacramento). Of course this pales in comparison to cities like Palm Springs (120°F/49°C on June 15), Las Vegas (117°F/47°C on June 16), and Phoenix (118°F/48°C on June 18), not to mention Death Valley (128°F/53°C on June 17). Yes, you read that right: Death Valley reached 128°F/53°C last Thursday; the highest temperature ever recorded there (and anywhere else on Earth) was 134°F/57°C in 1913. 

According to the UC Davis weather and climate station, Davis got to 112°F/44°C on Saturday. The highest I saw on our outdoor thermometers was 106°F/41°C, but even that is plenty hot. I hunkered down inside under a ceiling fan and binge-watched Netflix's new Icelandic series Katla. It's set on and around the subglacial volcano of the same name, and merely seeing how cold people looked on screen helped me feel cooler.

Prior to the peak of the heat wave, I brought a tray of potted dudleyas inside. Everything else stayed outside, although I covered some recently planted cacti with window screening. 

Here are some quick observations from this morning (Monday, June 21).

Aloe karasbergensis and sundrops (Calylophus hartwegii)

Many aloes have folded up their leaves in response to the heat, protecting the growing points in the center:

Aloe conifera, Aloe karasbergensis, Aloe microstigma × capitata

A few mangaves and agaves are trying to do the same thing:

×Mangave 'Mission to Mars', Agave weberi 'Arizona Star'

As you can see in the next photo, ×Mangave 'Red Wing' is completely unfazed while Hechtia argentea next to it looks bleached and borderline sun-burned:

×Mangave 'Red Wing' and Hechtia argentea in one of the hottest spots in our garden, right next to the sidewalk which radiates heat all day

Some plants did get burned:

Aloe vaombe

The newly flushed leaves on this Encephalartos friderici-guilielmi didn't have enough time to harden off before the heat wave started. The leaf tips are burned and will eventually fall off.

Even this sun-loving buckwheat (Eriogonum latifolium) got burned. It's native to the coastal scrub of the West Coast, so not as heat-tolerant as other buckwheats.

This Delosperma 'Granita Orange' had been blooming profusely for months, but last week's heat was simply too much. It's too early to say how extensive the damage is.

Some Dudleya species, especially the ones growing right on the coast, have thrown in the towel and are quickly going dormant. I'll know in the fall whether it's seasonal or permanent:

Dudleya farinosa

In spite of the intense heat, most plants look OK. Some, in fact, seem to be thriving:

Epilobium canum (most likely 'Silver Select') has never looked better

Dioon edule 'Palma Sola' with new leaves. Summer heat seems to trigger flushing.

Hechtia marnier-lapostollei and Grevillea 'Kings Celebration'

Echinops ritro subsp. ruthenicus, with Grevillea 'Kings Celebration' behind it

This Echinops ritro subsp. ruthenicus makes me particularly happy. For some reason, globe thistles aren't as easy to grow for me as you might think, but this subspecies, bought in the fall at the UC Davis Arboretum plant sale, looks to be a winner. It's just now starting to flower.

Agave wocomahi is fast becoming one of my current favorites. Related to, but hardier than, Agave bovicornuta, this species deserves to be much more common in cultivation. My plant has almost doubled in size this year. Agave palmeri (dwarf form) behind it on the left and Agave sebastiana on the right have also put on noticeable growth.

Right now, we're getting a respite from the heat, but it looks to be short-lived: I'm seeing 103°F/39°C for Saturday and 108°F/42°C for Saturday in the forecast.

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  1. OMG that is hot! and here I am complaining about 86 F (30 C). It is interesting to go around and see who is embracing the heat and who is packing it in. Spring bloomers were enthusiastic but the flowers display was short lived. Seems everyone on the west side of the continent is super hot and very dry right now. Bit disturbing.

    1. Everything seems to have gotten so much more extreme. Given our Mediterranean climate, we won't get any summer rain, but I'm hoping Arizona and the Southwest will have a good Monsoon season.

  2. Yikes. That is brutal heat. Downright dangerous if the power goes. We lucked out here--the heat didn't quite make it to the coast. One day hit 93F and that was it. Farther inland they were sweltering. The plants are going to do what they are going to do. Take care this weekend.

    1. Your climate is, in many ways, perfect for gardening, no doubt about it!

  3. Ugh. That 's in the misery range. A few years ago, when we hit 110 and stuck there for a couple of days - generally not cooling down below 100F until near midnight - I saw a lot of plant damage, not all of which was immediately evident when the thermostat was turned down. When we go over 100 and stay there, the lemon tree at the bottom of our back slope immediately drops most of its fruit, and what doesn't drop rots in place. I'm dreading this summer given how dry we are already.

    1. Fortunately, we cool off most nights thanks for an influx of colder air from the Sacramento-San Joaquin Delta. Even on a 100+ degree day, our nighttime low is typically in the high 60s.

  4. Is Palma Sola variegated? We're watching here on the heat wave you guys are experiencing there. Fascinating to see some of the succulents protecting themselves and glad to see most of your plants are doing fine despite the heat.

    1. No, 'Palma Sola' isn't variegated, but the new leaves are much greener than adult leaves.

      Ultimately, succulents are much better equipped to handle the heat than humans are!

  5. A mental slip there at the beginning with the date? (July 21) It sure feels like July! Things look pretty fabulous considering. We topped out at 97 yesterday, I haven't been able to see the garden yet to know how things took it. Next weekend we're joining you in the oven. So far predictions are all over the place but it is likely at least four days will be at or above 100 (some going as far to say 110, which I am refusing to even think about). Oh and did I mention I can't get around the garden???

    1. Freudian slip! I guess I wouldn't mind it being July already--one month closer to the end of summer :-)

      I feel for you. It sucks not being able to get around!

  6. Hopefully there's no losses from the heat, but those are crazy temps. And yet your 'Red Wing' mangave looks magnificent! The 'Red Wing' you gifted me is slowly coloring up here, with no shockingly hot temps so far to scald it. We've been getting off easy here at the coast so far but there's a lot of summer left...

    1. We're headed towards 100°+ territory again. Ugh. Still, we're used to it more than Portland, which looks like it's about to obliterate all-time heat records.

      Glad your 'Red Wing' is turning red. As you saw, they really don't mind hot sun at all.


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