My babies are sick

I'm a first time grower suffering from first time growers' anxiety. But first, let me tell you a little about my babies. I have 5 white widows and 1 afghani. I started germinating on 1/14/08 and moved them into 1" rockwool cubes on 1/16/08. I am using GH flora series nutrients and have been soaking the cubes in a water mixture of equal parts micro and grow. Up until now I haven't had a ppm meter so I've just been trying to keep the concentration low. I only have a drip solution to test the pH so all I know is it's somewhere around 6.0. And I have each plant under her own 27W 5500K CFL in a well ventilated room that stays between 70-75f degrees.

Now yesterday I started noticing problems. If you look at the pictures you can see some classic signs of nutrient burn like browning at the edges but a lot of them seem to have different looking symptoms. Some are browning from the outward edges in and some from the base of the leaf out. Some have just small black necrotic spots between the veins. Some of the first serrated leaves are curled tightly underneath. The largest ones first serrated leaves actually turned upward. One however has not shown any symptoms. And also they seem to be growing at very different rates.

I assumed nutrient burn. I flushed them last night and again today with filtered water and with my new meter have adjusted their nutrient solution to about 500 ppm. Is there something else more heinous at work here or is it just nute burn mixed with paranoia? If it is nutrient burn, is there something else I should be doing? Thanks very much for any input.

i would use just water until you get some more roots coming out of those cubes then use a real light feeeding. if the directions say 1/2 tsp use 1/8 tsp

Should I be using pH adjusted water? Right now I've just been using activated charcoal filtered water. And how exactly do I flush rockwool cubes? I've soaked them in filtered water for about 1-2 minutes each about three different times now and they seem to be still getting worse. Is there something else I'm not doing right or do they just need a little time before they stop developing new symptoms and get better?

Babies don't need over 300 ppm. Flushing was a good thing.

probably too much water . depending on where you live you could flush the cube with your faucet . do you have good drinking tap water where you live if so its probably ok to just flush with. then squeeze the cube a little and let it dry a little for a day or two. i used to overwater clones and found i had much better success if i let the cubes dry out a little between waterings
moist not wet

My tap water is about 20 ppm so I figured it would be better to use filtered water. I'm just not sure what else I can do to flush the rockwool other than soak them; but then that runs the risk of overwatering. Although I suppose that is better than nute burn. About how long should it take before they stop getting worse? New leaves are still turning brown and I had hoped that the ill effects would stop as soon as I flushed the cubes. Thanks for all the help so far.

There is a little lag time but you should see new growth within 3-4 days if you corrected the problem (assuming it was a correct diagnosis of the problem).

misterF said:

My tap water is about 200 ppm so I figured it would be better to use filtered water. I'm just not sure what else I can do to flush the rockwool other than soak them; but then that runs the risk of overwatering. Although I suppose that is better than nute burn. About how long should it take before they stop getting worse? New leaves are still turning brown and I had hoped that the ill effects would stop as soon as I flushed the cubes. Thanks for all the help so far.

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misterF,sounds like your doing the right thing,I just run a light ph balanced nutrient solution through the blocks and let the water run out the bottom and then let them dry for a couple of days..let the roots start looking for water..remember rockwool hold alot of water so they can go a little before the next watering..you said you were using grow and micro..I also use general hydro..but were is the bloom..young plants need the bloom for developing a good root system, I give my clones equal amounts of each and a drop of superthrive..no problems, hang in there and good luck

Thanks for the tip. I'll add some bloom to my mix as soon as they are looking better. Right now I'm just using filtered water. All the feeding schedules I've found online or with my nutes seem to start at clone and I wasn't sure if seedlings needed different feeding than clones.

I've also put all my babies in a humidome which maintains about 80% humidity and have added a little supplemental c02 so I've got my fingers crossed that they'll pull through. Any other thoughts/suggestions are greatly appreciated.

Thanks for all the help!