Dying plants! Yellowing and curling

Hey everyone, This is a first M grow for me. I'm no newbie to horticulture or mycology. I have grown numerous types of orchids, cacti, and vegetables indoors and out for years. Growing entirely under artificial light is new to me.

These plants are about five weeks old and struggling to stay alive. The tips of the new leaves start to yellow immediately. The yellowing progresses to the rest of the leaf and then the leaf dies. Already four plants have died. They all seem to be exhibiting failure to thrive. I've read the faq and can't seem to put my finger on it. There may be more problems than just one. I have also read the international cannagraphic pictoral problem page.

Some basic info on the plants. They are grown under a 250W MH placed 12" above the tops. It was 5" from the tops but they got way too hot (95+) during the days. All the plants are in a 4x4x6 box ventilated to the outdoors with an oscillating fan on the floor. Vegetative temperatures are around 82-85. The problems really started when I switched from peat pots to full soil. It is close to the 'best bud' mix from Sinse Tips.

It is mostly worm castings, some vermiculite, perlite, peat moss, compost, kelp meal, splash of rock phosphate, garden lime etc. Could someone please give me some additional ideas on what's the cause for the death of these plants? I'd rather not see them all die. Thanks very much!

in the mean time i think you should throw them outside for a bit.. to get them going !

Okay first off, don't throw them outside= different light schedule, temps, etc=stress.

Your problem is your RIDICULOUS soil mix! You've got a bit of everything in there. Some of that stuff (peat) is strongly acidic. Some is basic. Some has WAY too much nutrient content (rock phosphate).

You are killing the plants with your soil. You need to flush it out VERY VERY well with plain tap water adjusted to pH 6.8. Measure the runoff pH while you're at it. Repot into a regular soil such as the compost mix listed in my siggy.

Also, those plants are too small to have been giving fertilizer. Right now you are going to need to do a foliar feed with a complete grow fert just to keep them from getting any worse while they root into new, better soil.

Read read read!!!

Thank you very much for your quick reply! So my best bet is to remove them from this rich soil and place them in a compost/humus/perlite mix? At what point as they start to recover will I want to start applying a fertilizer? I was hoping to go all organic which is why I used the mix from Sensi Tips.

As far as foliar feeding, most people say once a week. How often should I do a foliar feed when it is the only form of feeding the plant will get? Thanks again for all your help!

Yes, put the plants in that mix.
You WILL be feeding liquid ferts soon. Give them a couple days after the transplant and feed with 1/2 strength grow fert. There are plenty of organic liquid ferts; I like the PureBlend Pro line.
Foliar feed LIGHTLY every couple days with again a weak fert solution until the point when you start giving nuted water again.