Two inches down at a drip, 98 degrees. Two inches down, a foot away, still 98 degrees so that little drip has no effect. Stuck a plastic jar lid under the same drip, still 98 degrees.
Water in the tank is 80 so obviously and unsurprisingly, dark colored drip line in the sun heats up the water in it. My little 10 minute sessions aren't enough to bring tank temperature water to the drippers.
In the shade of a tomato plant - 2 inches down, 86 degrees.
Tallest grassy area in an aisle, 86 degrees.
Under a pile of weeds sitting in the shade, 81 degrees. I have no pile of weeds sitting in the sun right now so I couldn't check that.
Full sun exposed soil 5 inches down, 80 degrees.
Two of three temp/germination charts I have don't even bother to give germination rates at 95 or more for cukes and beans. Could still be old seeds. Mulch and reseed will tell.
Mulch the whole thing and I'd be down in the low to mid 80s instead of 98. I think it's shady there now and I have a dozen square bales of hay taking up space in the tunnel. ttyl
It has never occurred to me to worry about the temp of the water I’m giving to my plants. Of course, I’m living on, ‘The Frozen Tundra’ so LIQUID WATER is a LUXURY (Like A/C!) for us all, but does that make a difference, I wonder?
This sounds like something for Paul to figure out. ;)