Purpling of underside of leaves
I noticed a few of my 3 week old seedlings were curling down last night. Other sypmtoms were purpling of the underside of the leaves with the veins staying green. Also the plants in general were leaning and sagging a lot compared to the day before.
From what I have looked at on the web it could possibly be phosphorous deficiency. The day before the symptoms showed up I had sprayed with a 1/4 strength 10-10-10 solution. The lowest the temperatures have gotten in there are 60.4 degrees.
Anyone have an idea?