Update (several days later)
To my astonishment (and relief) exposed aeoniums came through the frost just fine. Those dark areas that looked for all the world to be damaged tissue? They simply went away. Same with my Agave americana 'Mediopicta Alba'. If you can shed light on why, do leave a comment below. Thanks!
Original post (morning after the frost):
Not good. This morning the birdbath was solid ice and lemons had frozen on the tree. Even those succulents I'd covered have patchy areas indicating damaged tissue. Those not covered (above) look worse.
Last night's forecast was 30 degrees, but parts of my garden likely went lower as cold air flowed and settled. Frost cloth and bedsheets added a few degrees, but it was the duration of the cold that made the difference.
Not all of this region---inland Southern CA---gets frost. Avocado and citrus orchards sit atop slopes so frost drains away. Hilltops often are well above 32F while valleys drop below.
Winter had been mild up to now. I was optimistic; I didn't think a late frost would be bad. Hopefully you saw frost advisories on the news or succulent designer Laura Eubanks' social media post showing she'd covered her own garden.
So...how are your succulents?
If you didn't cover them, is it too late? If there's damage, what's to be done?
You won't be able to tell the extent of the damage for a few days. That's time to rethink what-goes-where, while also keeping summer concerns in mind.
It comes down to microclimates
Case in point: After getting tired of covering them in winter, I now grow crassulas only along my home's east-facing wall, beneath eaves. There they get morning sun, are protected from cold, heat, harsh sun and hail, and benefit from the wall's radiant warmth.
Dead and damaged plants
If jades, kalanchoes and others turn brown and collapse, should you remove them?
Wait until the weather warms---late March---then prune damaged plants back to healthy tissue. (Leave dead top growth for now; it helps insulate.) Spring works wonders, and plants grow fast after late-winter rains.
Pruning is fine for shrub succulents but not most rosette succulents. Once aeoniums, aloes and agaves freeze, leaves fall off or die along tips and edges. The good news is succulent roots are shallow, and removal is quick: Yank-and-toss.
When trees are important
Along the coast, where temps range from the low 40s to the high 80s, most succulents are fine out in the open. Inland, trees and eaves offer important protection for tender succulents---something to consider at planting time.
Here, in the foothills NE of San Diego, I have few deciduous trees because I want year-round canopies that moderate excessive sun, heat and cold.
I've noticed that after succulents mature and fill in, leaves filter down through them and disappear. In fact, hardscape under my oaks invariably looks messier than adjacent planted areas. During hot weather, I blast with a hose those succulents with dry leaves and acorns in their crowns. Year-round, I sweep (or blow) debris from steps, patios and walkways.
I'll keep my plants covered for a couple more nights, until lows safely rise above the mid-30s. If you haven't covered your succulents, well, the worst is over, and (sad to say) once the damage is done, there's probably no point in doing so.
So, how did your garden fare during the frost?
Comments, questions, tips, and suggestions are welcome! Kindly include your city or region. As you can tell from above, It matters!
Related Info on this site
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Depending on how long temps stay below freezing (32 degrees F), “frost tender” succulents may show varying degrees of damage. When moisture in the cells of a vulnerable plant freezes, it expands, bursts cell walls, and turns leaves to mush. In a “light frost,” leaf tips alone may show damage (“frost burn”). In a “hard frost,” temps stay…