These girls are about 3-4 weeks from harvest, the night temps have fallen down into the mid 60’s. One plant is starting to purple up on the main stem, down low and side branches starting to also purple. The other plants have purple spot where leaf fingers meet and one is starting to turn purple down that one leaf.
I know purple can be a sign of phosphorus deficiency, but it can also be because of cooler night temperatures. I have decided to top dress with coffee grounds but does anyone know the amount to use?