I never really paid that much attention to the water temps in my cold frames compared to the ponds left uncovered. I could feel the water was warmer whenever I stuck my hand in. Well last night on a whim I decided to check & put the probe about 6" below the surface. Got readings of 68 in my uncovered ponds & 77 in the covered ponds. Starting to see baby tropical lily pads
at the surface in the coldframes but no activity on the tropicals that are in the uncovered.
One of these days I hope to be living with a bigger yard so I can have a proper greenhouse
If you've got a greenhouse, would love to see pics.