Your friend is pulling your leg :-) But maybe not intentionally. First, soil temperatures are quite slow to react to changes in ambient air temperatures. They will retain their level of heat for days, not just overnight. At most you could expect a drop of a degree or two. Second, enclosed/contained potting soils exposed to all day sun and heat can sometimes heat up more than you expect. If air temp is 85, the soil could be as much as 10-15 degrees warmer. In which case, even a drop of a degree or two overnight is of no consequence.

(ps. the air also tends to be very still at night, so very little "air flow" to be concerned about.)

Elevated garden beds work perfectly well and tons of balcony and rooftop gardeners use them with great productivity!

I had some at my old place that also didn't perform well. We're in Sonoma County and out in the country low lands, so it was a bit cooler than the norm.

I did OK with lettuces, and other winter stuff. Kale and chard, but once it heated up (80's-90's) everything fried. But I might not have been as attentive as I should have!

The beds were 3x8x1'.

Thanks! For what it’s worth, there is a lot of air flow at night around here - the temp drops 30 degrees in a few hours so it gets quite windy.

nancyjane_gardner sounds like we had similar issues. Anyway - I added some compost to the soil since it seemed pretty loose and aerated. We’ll see what happens!

"the temp drops 30 degrees in a few hours so it gets quite windy."

One has nothing to do with the other. Check any meteorological website - the air starts becoming still after sunset and is at its stillest prior to dawn, regardless of any temperature drop.

You might try adding some 'loam' to your raised beds. Yes I know there may be a weight issue in your situation...

My experience is that highly organic (lots of organic matter like composts) soils in raised beds can easily get hydrophobic when using drip irrigation - the areas which are not getting wet grow over time as the newly dry soil areas are not able to wick moisture as before. The soil down a foot may be fine but the surface 6" is not retaining moisture unless it is right next to drip emitter. This makes it hard to get transplants started...

Really hot weather just makes the problem much worse.

Reducing the OM content has largely solved this problem for me.

the same thing happens in Large pots if you don't have a lot of emitters...

Yes I could hand water more often, but I have a job and stuff...

That’s great insight chadinlg! This particular bed isn’t irrigated (hand watered) so I shouldn’t have that issue but I did notice that in my irrigated pots.

Thanks!