I had deep purple interveinal undersides on my seedling back in early February and some leaf curling. I decided it was phosphorous deficiency as well and repotted them all with extra bone meal, gave them a foliar feeding, and provided extra bottom warmth. (Apparently, cool *SOIL* temperatures can interfere with phosphorous uptake, even if there is sufficient phosphorous present in the soil.)

The sagging would worry me a bit--make sure the soil isn't soggy.

Anyhow, my seedling started looking better within 24 hours, became monsters within a month, and are now doing well planted under wall-o-waters in my garden!

Follow the phosphorous idea--maybe all some bonemeal, and try to give them a little extra bottom warmth, and keep us posted!

Thanks for your help. I have been using cold tap water. That may contribute to the problem.

I actually prefer watering mine with at least tepid water; usually a little warmer than room temp (I like the water about 80 degrees F) because many of the plants like the soil around that temperature.

PLease ignore the purple undersides to the leaves.

All will be well when they get outside.

It's impossible to ID specific mineral deficiencies with accuracy.

if the purple bothers you then spray with dilute fish or seaweed prep, both of which are rich in minerals. This bypasses root uptake if the seedlings are being grown too cool, which often is the reason why nutrients can't get taken up correctly.

Carolyn