Purple leaves/stems on WS toms only
This year was pretty much a categorical fail across the board for my WSing. Last year was a dream and I used the MIracle Grow Water Retention stuff--in other words the stuff everyone says not to use. This year I searched high and low for ProMix, happily sowed everything and the results were so disappointing. Half of what I sowed never came up even after 2 straight weeks of day temps in the 70+
My tomatoes are the worst. Of the 8 varieties I WSed, only two have small but healthy looking sprouts with true leaves. The rest are tiny, spindly, with deep purpling on the stem and leaves. They are runts with curling suffering leaves.
An internet search suggests this is usually because of cold temps (which may additionally inhibit Phosporus uptake). However: 1) this purpling has persisted, perhaps even worsened, during the last two weeks when we finally got great temps around 70+ during the day and 55+ at night. 2) worried that my WS plants werent germinating I used the same seeds, the same soilless mix, and sowed some tom seeds inside. They stayed inside only until the first green poked up and then they went straight outside with the rest, but they are now considerably taller and healthier than their WS siblings of the same tomato variety and same seed stock (see Cherokee Purple below, WS in the jug compared to its sibling in the solo cup).
Can some more experienced WS person help me understand why my WS tomatoes seem so much more sickly and what if anything to do about the purpling on those? should I transplant them out of their WS jugs?