problems with california fan palm seedlings

Hi-
hopefully someone has some experience and could help. I started 189 seeds and got all but about a dozen to root. i transplanted seedlings started in 1.5" rockwool cubes into 4" pots filled with a local coco/perlite blend. i built a rolling tray to keep em on and also so i can move them around in and out of wind/rain/sun. they looked great getting full sun for about 2 weeks then the tips started to redden and a couple bent all the way over. they've been fed a root starter and a cal/mag/nitrogen liquid fert, the roots are growing really slow too. they are about 5-6" tall and don't seem to be growing much if at all. if anyone has any suggestions on getting these little guys happy and healthy i'd sure be grateful...

what species are we talking about? Mixture might be too well draining allowing roots to dry out too much. Easy on the fertilizer, too

Washingtonia filifera.
i'm right on top of the watering and they don't get dry or soggy, i've used this mix with lots of other plants..
so palmbob with what and how often would you fertilize? i used this medium so i could feed more often but not sure what food they need- preferably organic. i have 3 established and several years old in my front yard so i know they can do well here, altho the largest one (like 3' tall) looks like it's got a mag deficiency on older leafs..
thanks for the quick reply palmbob.
we need smilie face emoticons on this site.

These germinate and grow in just about anything... dirt would be fine, or potting soil, or a sany mix. Just not sure about coconut and perlite. Probably I would start to fertilize once they had 3-5 leaves. And then with super diluted liquid fertilizer maybe once a month (this species needs very little in the way of fertilization). Personally I would probably never fertilize these, but I think they would be happier with some now and then

right on palmbob- thanks for the tips!