My last grow went fantastic with the Ugro max air but this time I was short on cash so I got the Ugro Air which doesn't have the perlite mixed in so I put my own perlite in for extra drainage, is it possible the perlite is contaminated because I stupidly left it in my green house outside with it taped shut in a bag so maybe it got fungus or something but the roots on the plant are white and healthy. The bag says it has a low percentage of coir fibres, not sure how low though. I'm watering much less now so hopefully it comes good. If I get another to pop finally which I'm having heaps of trouble with im thinking of going without perlite maybe? I'm actually buying a new pH pen tomorrow, the bluelab pH pen & I'm going to get the care kit which has all of the calibrating stuff in it & I'll get the guys at the shop to calibrate it which they didn't do last time. I didn't know that was a big thing when I got the AZ one I have now, it's super slow, it has no indicator of when it's finished reading and it's never been calibrated so that's probs why. I'll calibrate the new one every few weeks like you say & keep on top of the pH. Thanks heaps for all your advice, really appreciate you taking the time to help me out. I have a harlequin in the hydro peroxide 15ml in 80ml of spring water soaking for 24 hours this time, maybe that will get it to pop easier, then if it does germinate I'm going to buffer a brand new peat pellet in the bio diesel buffer nutrient solution then water very sparingly. Fingers crossed it does the trick because I should be like a month into a new grow.
I grow in straight coco, but I filter out much of the coffee ground sized coco peat so the media is mostly fibrous coco. I can water daily right from go with most seedlings. I think growth is a bit faster for the first week or two when using perlite due to the extra aeration it provides, but I hate dealing with bags of dusty perlite (have to use N95 mask because that shit is very harmful for your lungs), so I stick with straight coco.
Remember that pH is on the logarithmic scale, so a point difference is 10x. At 6.7pH you are out of range but being that your pen isn't calibrated, I wouldn't be surprised if it's into the high 7's. When you get your 7.0 reference solution, dip that pen in and see what it reads to get an idea of how off the pen is.
I see someone else said you waited almost 2 weeks to feed. Now I see in your OP that you went 12 days. When you prepare your coco, the final step is to run a feed of 0.4EC (200PPM on the 500 scale) thoroughly through the coco to charge the media a day or two before you plant so the taproot will have access to a light nutrient mix. You can continue to feed that 200PPM feed right from go once it emerges from the coco.
With that extra information, I think the leaf twisting is from too high of pH. The cotyledons turning yellow is definitely a nitrogen deficiency. The missing leaf pair could be calcium or boron deficiency - they both can present with incomplete/distorted leaf formation before necrosis starts. If that weird leaf is thick and brittle, it's probably boron. But none of that minutia matters - just hit it with a good dose of some food.
It's from lack of food I think. You waited 2 weeks almost before feeding. I think if you feed and PH correctly they should bounce back.
Agree. Just needs some nutrition and the pH corrected and will be fine.
